Sterrekunde

Waarom is Pluto se resonansie eers in 1965 ontdek?

Waarom is Pluto se resonansie eers in 1965 ontdek?


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Hier was ek geskok toe ek geleer het:

Die Neptunus-Pluto-stelsel lê in 'n 3: 2 orbitale resonansie. C.J Cohen en E.C. Hubbard by die Naval Surface Warfare Centre Dahlgren-afdeling het dit in 1965 ontdek.

Opmerking: daar is geen aanhaling daarvoor nie.

Ek is redelik seker dat die wentelbaan van Pluto, ook die periode daarvan, baie jare voor 1965 bereken is, om niks van Neptunus te sê nie. Hoe is dit dan moontlik dat sterrekundiges die 2: 3-resonansie misgeloop het? Was orbitale resonansie tot die sestigerjare net nie 'n denkbeeldige konsep nie?


Soveel kan ek antwoord:

Was orbitale resonansie tot die sestigerjare net nie 'n denkbeeldige konsep nie?

Laplace het 'n lang resonansie herken, en hy is oorlede in 1827. Ek het gekyk, kon nie 'n presiese jaar van publikasie vind nie.

https://en.wikipedia.org/wiki/Orbital_resonance#Laplace_resonance

Nou, 3/2 resonansies is miskien heelwat later voorgestel / ontdek, ek is nie seker nie.

Sommige wiskunde oor die onderwerp in die volgende skakel, 'n bietjie meer as my vaardigheid, maar dit maak die punt van stabiele resonansie.

http://www.applet-magic.com/solaresonance.htm

Die skakel wys ook daarop dat die eerste resonansie wat ontdek is, Io, Europa, Ganymedes die 1-2-4 resonansie, verhoudings van 2.0076 en 2.0143 het, of, 0.4% en 0.7% afslag op resonansie.

Ek is in die versoeking om te sê dat sulke klein variasies binne 'n stabiele sone val, maar ek sou eintlik net raai. Ek kan nie met sekerheid sê nie.

Pluto is in 1930 ontdek en Charon, dit is 'n groot maan, word eers in 1977 ontdek. Miskien in die dertigerjare was Pluto nie meer die nuutste fisika nie, en al die groot breine het gekyk na die kwantumfisika, die ontdekking van Hubble en ander sterrestelsels, die gevolge van Einstein se ontdekkings, soos swart gate en kernbomme ... maar weer, ek bespiegel net. Dit wil voorkom asof 'n ontdekking van die 3/2 resonansie voor 1965 moes kom, en ek dink dit is 'n goeie vraag.

Nie om dit te onderwerp nie, maar ek hou van die verhaal van hoe Neptunus ontdek is. Kort opsomming hier: http://coolcosmos.ipac.caltech.edu/ask/146-- When-was-Neptune-discovered-

Langer een hier: https://en.wikipedia.org/wiki/Discovery_of_Neptune

My gunsteling potensiële baanresonansie is die Jupiter / Mercurius, wat uiteindelik Mercurius van die son kan wegtrek.

https://en.wikipedia.org/wiki/Stability_of_the_Solar_System#Mercury.E2.80.93Jupiter_1:1_perihelion-precession_resonance

Die Jupiter / Mercury-resonansie word in die artikel as 'toeval' beskryf, waar Pluto se 3/2 met Neptunus en Jupiter se 3 binnemane (dink ek) waarskynlik nie toevallige resonansie is nie, maar 'n vorm van stabiele wentelbane.

Hoop u gee nie om vir my amateur / hobbyist antwoord nie.


7 Wilde mites oor Pluto

Faraway Pluto is moeilik om van die aarde af te bestudeer, en die dwergplaneet het dus grootliks geheimsinnig gebly vir wetenskaplikes en leke sedert sy ontdekking in 1930.

Maar Pluto is op die punt om sy eerste close-up te kry. Op 14 Julie sal NASA se New Horizons-ruimtetuig net 12 500 kilometer van die dwergplaneet inzoomen en superscherpe beelde van sy ysige oppervlak neem.

Met hierdie hoogs verwagte onthulling van minder as ses weke weg, is dit nou 'n geskikte tyd om 'n paar van die mees algemene mites en wanopvattings oor Pluto te besoek. Hier is 'n kort oorsig. [NASA se New Horizons Pluto Mission in Pictures]


Waarom is Pluto se resonansie eers in 1965 ontdek? - Sterrekunde

Onlangs is toenemend aantal asteroïde-voorwerpe in die buitewyke van die sonnestelsel ontdek, anderkant die baan van Neptunus. Hierdie streek staan ​​bekend as die Kuiper-gordel. Hierdie voorwerpe word in 'n aparte kategorie van asteroïdes geklassifiseer, en word eenvoudig genoem Kuiper-gordelvoorwerpe (KBO's) . Dus moet ons die term asteroïde beperk tot rotsagtige liggame met wentelbane met semi-groot asse tussen Mars en Jupiter, die sg. Asteroïde gordel , of miskien 'n paar ander voorwerpe wat 'n dinamiese verband hiermee het - d.w.s. hulle was moontlik een keer deel van die asteroïedegordel, maar is in 'n ander baan uitgegooi.

Let daarop dat daar 'n groot gaping is (van binne die baan van Jupiter tot buite die baan van Neptunus) waar daar min of geen voorwerpe tussen die Asteroïde-gordel en die Kuiper-gordel is nie. Hierdie twee verspreidings is dus goed geskei, en die samestelling van die liggame is ook baie anders. Hier is die verspreiding van KBO's en komete in die buitenste sonnestelsel. Let daarop dat hierdie plot vir VANDAG is! Die wentelbane word daagliks gevolg en kan geanimeer word. Dit moet vergelyk word met die verspreiding van hoofgordelasteroïede. Weereens is 'n geanimeerde weergawe beskikbaar.

Ons sal in die volgende lesing oor asteroïdes praat, maar let op dat die skema van asteroïde-benamings: (genommer in volgorde van ontdekking, gevolg deur naam): bv. 1 Ceres, 951 Gaspra, word gedeel deur die Kuiper-gordelvoorwerpe, bv. 2060 Chiron, 7066 Nessus. Daar kan na beide asteroïdes en KBO's onder die algemene naam verwys word Geringe planeet , met die groter (groot genoeg om bolvormig te wees) genoem Dwergplaneet.

Hier is 'n kunstenaar se opvatting van die grootste bekende KBO's, wat hul relatiewe grootte en bekende mane toon. Let daarop dat Pluto, wat eens as 'n planeet beskou is, nou bekend is as een van die KBO's en dat hy amptelik 'n dwergplaneet is. Sommige mense, veral Amerikaners, is ontsteld oor die & quotdemotion. & Quot

Hieronder is 'n figuur wat die relatiewe groottes toon van sommige voorwerpe van die sonnestelsel, insluitend Pluto regs onder:

Hoe word groottes en afstande bepaal? Afstand is relatief maklik, deur verskeie posisies van 'n voorwerp in die lug waar te neem, kan die baan bepaal word. So 'n bepaling gee uniek die afstand tot die voorwerp. Sodra die afstand bekend is, kan die optiese helderheid gebruik word om die grootte te raai, maar slegs as ons weet hoeveel lig dit weerkaats (sy albedo). Die kurwe gemerk "Opties" in die onderstaande figuur, vir die KBO 20000 Varuna, toon die lokus van moontlike groottes en albedo's uit die optiese metings.


Nou 'n fraksie A (die albedo van die voorwerp) van hierdie helderheid word weerkaats en beweeg weer na buite in alle rigtings om die aarde 'n afstand te bereik d weg van die voorwerp. Die vloed van sigbare lig op die aarde, wat weerkaats word vanaf die voorwerp, is dan:

F vis = A(L asteroïde / 4 bl d 2 ) = A(L son R 2/16 bl D 2 d 2 ). (1)

    FIR = (1 - A)(Lasteroïde / 4 bl d 2 ) = (1 - A)(LsonR 2/16 bl D 2 d 2 ). (2)


waaruit A kan direk bepaal word. Uit hierdie oorwegings kom ons kennis van die albedo's en groottes van die meeste asteroïdes en KBO's.

Daar is meer te leer oor individuele voorwerpe deur na hul IR-spektra te kyk. Kyk na hierdie boeiende artikel oor Haumea, wat 'n rooier kol op hierdie groot, vreemd gevormde, vinnig draaiende KBO vertoon.

  • Asteroïdes
    • Hoofgordelasteroïede (tussen Mars en Jupiter)
    • Trojaanse asteroïdes (op Lagrangian-punte met Jupiter, 60 o voor of agter Jupiter)
    • Naby Asteroïdes
    • Centaur-asteroïdes ('n klein gesin met semi-belangrike asse tussen Saturnus en Uranus)
    • Klassieke KBO's
    • Verspreide KBO's
    • Plutinos (voorwerpe soos Pluto wat in 3: 2-resonansie met Neptunus is)
    • Centaurs ('n klein gesin met semi-belangrike asse tussen Saturnus en Uranus, wat net 10 My kan leef)

    Pluto is interessant vanweë sy geskiedenis as die eerste ontdekte KBO, en sy aanwysing as 'n planeet. Dit het ook 'n interessante voorgeskiedenis (die tyd voordat dit ontdek is). Percival Lowell het in 1906 begin met 'n gesamentlike poging om planet X te vind en 'n hipotetiese planeet anderkant Neptunus. Die plek om te soek is gebaseer op berekeninge van die baan van Neptunus wat blyk te wees dat dit deur een of ander onbekende liggaam versteur word. Onthou dat Neptunus ontdek is na soortgelyke berekeninge van die versteurings van Uranus, so die idee was waarskynlik. Na 'n soektog van tien jaar, het Percival Lowell leeg opgekom en gesterf sonder om die planeet X te ontdek. In 1930 ontdek sy protege Clyde Tombaugh Pluto naby die plek vir planeet X. Hierdie ontdekking het wêreldwyd groot nuus gemaak en 'n skoolmeisie in Brittanje het die naam Pluto voorgestel, waarvan Tombaugh gehou het omdat sy eerste twee letters, PL, die voorletters van Percival Lowell is. As die enigste planeet wat deur 'n Amerikaner ontdek is, het Pluto vinnig deel geword van die Amerikaanse psige, wat gehelp is deur Walt Disney se skepping van Mickey Mouse se lieflike troeteldierhond Pluto.

    Ongelukkig is vinnig vasgestel dat Pluto te klein is om Planet X te wees - dit kan nie die bron van die skynbare versteurings van Neptunus wees nie. Uiteindelik is vasgestel dat hierdie versteurings bloot foute in die oorspronklike massa vir Neptunus was, en met die presiese waarde wat tydens die vlieg van Voyager 2 na Neptunus bepaal is, het die bewyse vir 'n planeet X verdwyn. Desondanks word Pluto as die negende planeet beskou totdat die ontdekking van ander KBO's misnoeë onder sommige wetenskaplikes veroorsaak het. Die kwessie het tot 'n punt gekom toe Eris in 2005 deur Mike Brown ontdek is. Omdat dit groter was as Pluto, is Eris informeel die 10de planeet genoem, maar dit het die Internasionale Astronomiese Unie gemotiveer om die kwessie van Pluto en KBO's die hoof te bied. Die probleem is dat daar voorspel is dat daar honderde KBO's van Pluto-grootte kan wees, waarvan die meeste nog onontdek is. Ons kan honderde planete hê, of Pluto kan afgebreek word om lid te wees van 'n ander klub, die sogenaamde dwergplanete. In 2006, in 'n taamlik kontroversiële stemming oor die kwessie, het 'n IAU-resolusie wel 'n definisie vir die term planeet geskep wat nie Pluto insluit nie, en het Pluto sodoende gedegradeer tot die status van die dwergplaneet. Daar is tekortkominge in die definisie wat dit nog steeds omstrede maak - en om die een ding is die definisie slegs van toepassing op planete rondom ons eie son, nie op ander sterre nie. Daar is tans 5 bekende dwergplanete, Eris, Pluto, Ceres ('n asteroïde), Haumea en Makemake.

    Let op dat dieselfde gebeurtenis in die 19de eeu plaasgevind het nadat Ceres, die grootste asteroïed met die hoofriem, op 1 Januarie 1801 deur Giuseppe Piazzi ontdek is. Daar word ook gedink dat dit 'n planeet is totdat die klein grootte daarvan bepaal is en die ontdekking vinnig gevolg is deur nog verskeie asteroïdes (Pallas, Juno, Vesta) in 'n soortgelyke baan. Uiteindelik is besluit dat Ceres net die grootste is van 'n nuwe klas liggame genaamd asteroïdes (waaroor ons die volgende lesing sal bespreek). Die geval van Pluto is dus baie parallel, behalwe dat die tyd tussen Pluto se ontdekking in 1930 en die ontdekking van ander KBO's langer was.

    Pluto se afgradering word ook gekompliseer deur die feit dat dit plaasgevind het na die lansering van die New Horizons-sending na Pluto, wat in 2015 deur die stelsel aangekom en gevlieg het. Ek noem Pluto 'n stelsel, want dit is bekend dat dit nou minstens 4 mane het (die grootste, Charon, is so groot as wat die Pluto-Charon-stelsel 'n & quotdouble-planet & quot-stelsel genoem is). Hieronder is 'n paar beelde wat die ontdekkings van die mane agtereenvolgens dokumenteer. Kyk na hierdie video's van New Horizons:

    Hier is 'n diagram van die pad van die New Horizons-missie na Pluto en die Kuiper-gordel.


    Herklassifikasie

    Diagram van die sonnestelsel. (Foto: NASA)

    In Augustus 2006 het Pluto moeilike tye aangebreek, toe die Algemene Vergadering van die Internasionale Astronomiese Unie (IAU) 'n resolusie aangeneem het om dit weer as 'n dwergplaneet te klassifiseer, omdat dit nie aan een van die drie nuut gedefinieerde kriteria voldoen om 'n planeet te wees nie. Diegene wat teen Pluto se aftakeling gekant was, noem die kriteria - waarvan een bepaal dat 'n planeet sy sonkraggebied moet oorheers - arbitrêr of irrelevant.

    Die besluit van die IAU, wat beteken het om jare se debat oor Pluto se status te beëindig, het 'n openbare ontsteltenis veroorsaak.

    Per slot van rekening het elke skoolkind die frase geleer: "My baie opgeleide moeder het ons net nege pizza's bedien", om die orde van die planete reg te hou, en nou het dit net nie sin gemaak nie.

    'Wat gaan ons baie opgeleide moeder ons dien?' vra Larry Faltz, Westchester amateur-sterrekundepresident, in sy onlangse nuusbriefartikel oor Pluto se aftakeling. ("Nachos" is een voorstel.) "Toe die akte in 2006 deur die IAU gedoen is, was dit moeilik om dit nie as 'n soort uitdaging te beskou vir ons geniale entoesiasme vir die nuutste lid van die gesin en ons liberale verwantskap met buitestaanders en underdogs, 'het hy geskryf.

    Interaktief: Pluto onthul

    Maar nadat hy die IAU se beslissing êrens deurgebring het, het hy dit aanvaar, het Faltz gesê.

    "Dinge verander, en ons moet aanpas," het Faltz gesê.

    Kunstenaar se indruk van hoe die oppervlak van Pluto naby die middag kan lyk. (Foto: SwRI / Alex H. Parker (NASA))

    Maar die verandering blyk nog moeilik vir ander te wees, waaronder Ed Siemenn van die Rockland Astronomy Club.

    "Ek is teleurgesteld oor die herklassifikasie," het Siemenn gesê. "Vir my sal Pluto altyd 'n planeet wees, en ek verwys nog steeds daarna as 'n planeet. Ek voel ongemaklik om dit enigiets anders as die planeet te noem. Ek het grootgeword in die tyd toe daar nege planete was."

    Thompson, van die Syracuse-universiteit, het die sentiment van Siemenn beaam.

    "Ek is 55 jaar oud, en wat my betref, is Pluto nog steeds 'n planeet," het Thompson gesê. "Ek het as kind soveel toetse afgelê waar ek die nege planete moes teken en die nege planete moes benoem. Ek het geleer dat daar nege planete was. Miskien reageer ek nie goed op verandering nie."

    Sophia Peluso, 'n tweedejaarskool Yonkers High School wat 7 was toe Pluto die byl gekry het, het gesê dat sy steeds hartseer voel oor haar gunsteling planeet wat degradeer word.

    "Ek hou baie van Pluto, want dit is klein, en ek hou baie van onderdog-soorte dinge," het Peluso, 'n junior dosent aan die Hudson River Museum in Yonkers, gesê. "Ek sien nie die voordeel daarvan dat Pluto nie 'n planeet is nie. Dit maak die hele akroniem vererger."


    Charon

    Charon ("KAIR en") is Pluto se grootste satelliet:

    Charon is vernoem na die mitologiese figuur wat die dooies oor die rivier Acheron na Hades (die onderwêreld) vervoer het.

    (Hoewel hy amptelik na die mitologiese figuur vernoem is, het Charon se ontdekker dit ook ter ere van sy vrou, Charlene, genoem. Diegene wat dit ken, spreek dit dus uit met die eerste lettergreep wat soos 'skerf' klink ('SHAHR en').

    Charon is in 1978 deur Jim Christy ontdek. Daarvoor is gedink dat Pluto baie groter is aangesien die beelde van Charon en Pluto aanmekaar vervaag is.

    Charon is ongewoon omdat dit die grootste maan is ten opsigte van sy primêre planeet in die Sonnestelsel ('n onderskeid wat eens deur die Aarde se maan gehou is). Sommige dink eerder aan Pluto / Charon as 'n dubbele planeet eerder as 'n planeet en 'n maan.

    Charon se radius is nie bekend nie. Die waarde van JPL van 586 het 'n foutmarge van +/- 13, meer as twee persent. Die massa en digtheid daarvan is ook sleg bekend.

    Pluto en Charon is ook uniek deurdat Charon nie net draai nie sinchronies, maar ook Pluto: albei hou dieselfde gesig teenoor mekaar. (Dit maak die fases van Charon, soos gesien uit Pluto, baie interessant.)

    Die samestelling van Charon is onbekend, maar die lae digtheid (ongeveer 2 gm / cm3) dui daarop dat dit soortgelyk kan wees aan Saturnus se ysige mane (d.w.s. Rhea). Dit lyk asof die oppervlak daarvan bedek is met waterys. Dit is interessant dat dit heeltemal anders is as Pluto.

    Anders as Pluto, het Charon nie groot albedo-funksies nie, alhoewel dit kleiner is wat nie opgelos is nie.

    Daar word voorgestel dat Charon gevorm is deur 'n reuse-impak soortgelyk aan die wat die Aarde se maan gevorm het.

    Dit is te betwyfel dat Charon 'n beduidende atmosfeer het.


    Internasionale komeet kwartaalliks

    Wel, miskien nie. Maar die moontlikheid bestaan ​​beslis. En die moontlikheid word al dekades lank bespreek (sien byvoorbeeld Fred Whipple se artikel in 1964 in Prok. Nasionale Acad. Sci. 52, 583). Wel, is Pluto dan 'n planeet? Ja, dit blyk 'n planeet te wees. Maar dit is redelik om dit te kwalifiseer deur te sê dat Pluto dit is nie a hoofvak planeet omdat dit eenvoudig te klein is om 'n groot planeet te wees (alhoewel die trots van baie Amerikaanse sterrekundiges veroorsaak dat hulle polities voortgaan om te veg dat Pluto 'een van die nege groot planete' genoem word). Dit is 'n planeet van een of ander aard, en baie planetêre wetenskaplikes het in die laaste paar dekades van die 20ste eeu van Pluto begin praat as 'n 'planetesimale' - en nie meer as 'n 'groot planeet' nie - in die astronomiese literatuur (let op die dosyn outeurs in die onderstaande gedokumenteerde lys). Dit is nie nodig om 'n 'edik' te hê wat sê dat Pluto nie die negende groot planeet is nie, aangesien sterrekunde nie regtig so werk nie, en die veld geleidelik maar geleidelik beweeg na 'n uiteindelike universele aanvaarding van 'n nuwe beeld van die son stelsel wat Pluto in 'n ander (maar steeds beduidende) lig plaas. En, ja, dit kan wees dat ons dit wil oorweeg om Pluto in verskillende kategorieë te plaas, soos (klein) planeet en komeet. Sulke "dubbele status" bestaan ​​reeds vir sommige komete en kleinplanete, wat in albei soorte katalogusse formele nommers en name kry.

    Die afgelope paar jaar het 'n slegte ingeligte bespreking in die gedrukte en elektroniese nuusmedia gesentreer rondom die vraag of Pluto 'n planeet is of nie, en sodanige besprekings oor Pluto nie uit die oog verloor het dat die kwessie oor 'major planet'-status was nie , nie 'planeet' status nie. Met klaarblyklik nie-sterre metgeselle wat in 'n toenemende tempo rondom ander Melkwegsterre ontdek word, word die kwessie oor hoe om die woord "planeet" te definieer ingewikkelder, en dit is duidelik dat die woord planeet in byna alle gevalle nodig is om het gepaardgaande kwalifiserende woorde ("major", "minor", "principal", ens.) vir die gebruik van die woord "planeet" om in enige gegewe konteks baie sin te maak. Maar moet daar groot komitees geskep word om 'n 'definisie' van die woord 'planeet' te bepaal? Waarskynlik nie. 'N Maklike definisie van 'n planeet is 'n interplanetêre liggaam wat om die son wentel (of waar ook al in die heelal geleë is) wat groter is as 'n meteoroid (wat klein interplanetêre gesteentes is met 'n grootte van, byvoorbeeld, 10 meter en kleiner). 'n ster of proto-ster (of bruin dwerg - miskien 0,01 tot 0,1 sonmassa). Hierdie webblad is saamgestel as gevolg van die gewilde vraag, bloot om baie verkeerde inligting oor Pluto reg te stel. In die middel van die negentigerjare het 'n paar planetêre sterrekundiges steeds onbewus gelyk dat tientalle van hul kollegas opgehou het om Pluto 'n "groot planeet" te noem. in die astronomiese literatuur (sien die gedokumenteerde lys hieronder).

    Omdat daar blyk dat Pluto nie 'n belangrike planeet is nie, 'sterf' die astronomie nie op so 'n manier nie - dinge word dikwels herklassifiseer of op verskillende maniere bespreek in die lig van nuwe kennis (en ' afgradering 'is eenvoudig 'n politieke, nie realistiese woord wat deur Pluto-is-negende-planeet-voorstanders in die Verenigde State gebruik word nie). Pluto is 'n baie belangrike en interessante voorwerp, met baie leidrade oor die oorsprong en evolusie van ons sonnestelsel, en dit sal wonderlik wees om 'n ruimtetuigmissie na hierdie trans-Neptuniese voorwerp te hê om veel meer daaroor te leer. Die klein voorwerpe van die sonnestelsel is op baie maniere net so belangrik, en meer op ander maniere belangrik, net soos die belangrikste planete!

    • 'n ster (die son)
    • vier reuse gasagtige planete (Jupiter, Saturnus, Uranus, Neptunus) met oor die algemeen stabiele elliptiese wentelbane met e 0.3), en waarvan die wentelbane noodwendig dus redelik onstabiel is, is diegene wat die baan van die aarde oorsteek, van groot belang en staan ​​bekend as "apollo-tipe" of "aten-tipe" klein planete, ander wat die wentelbane van een of meer van die buitenste groot planete kruis. dinamies gekategoriseer as "sentaurs" of "voorwerp met verspreide skyf"
    • komete, wat gewoonlik baie elliptiese wentelbane het (e In die meeste gevalle> 0.35 en dikwels> 0.9) word gesien dat sommige komete uit die sonnestelsel uitgegooi word as gevolg van noue benaderings tot groot planete, soos Jupiter-komete, is daar gewoonlik onstabiele wentelbane vanweë hul potensiaal vir herhaalde nabye benaderings tot sulke planete.
    • trans-Neptuniese voorwerpe (TNO's) in 2: 3-resonansie met Neptunus (wat beteken dat hulle twee keer om die son wentel vir elke drie keer wat Neptunus doen), blyk dit oor miljoene jare betreklik stabiele wentelbane te wees. Pluto is die grootste voorwerp in hierdie groep. , wat ongeveer 'n derde of meer van al die honderde bekende TNO's uitmaak, en die voorwerpe in hierdie groep word nou "plutinos" -bane genoem, het matige eksentrisiteite (gewoonlik 0,1

    Let op dat die feit dat (1) Ceres in 1801 vir die eerste keer ontdek is, vermoedelik 'n "gewone" planeet was (nadat dit aanvanklik as 'n komeet beskou is, dit wil sê Uranus is ook beskou as 'n komeet toe dit vir die eerste keer ontdek is, omdat die konsep van nuwe 'planete' twee eeue gelede nuut was). Hierdie vermoede het ook geld vir die volgende drie hoofgordel-asteroïdes (wat in 1802, 1804 en 1807 gevind is): hulle is almal beskou as nuwe planete van die sonnestelsel en is gereken as die 8ste, 9de, 10de en 11de planete (of 5de, 6de, 7de en 8ste - met Jupiter, Saturnus en Uranus het na die 9de, 10de en 11de plek beweeg). Die vyfde asteroïde is eers laat in 1845 gevind, en die sesde eers in die middel van 1847, en astronomiepublikasies en handboeke vir byna 'n halwe eeu verwys na 'elf primêre planete' van die sonnestelsel [bv., P. A. Hansen (1837), in Jahrbuch fuer 1837, red. deur H. C. Schumacher (Stuttgart en Tuebingen: J. G. Cotta'schen Buchhandlung), p. 83 D. Olmsted (1847), 'N Inleiding tot sterrekunde ontwerp as 'n handboek vir die studente van Yale College (New York: Collins and Brother), p. 174 J. H. Wilkins (1833), Elemente van sterrekunde (Boston: Hilliard, Gray, Little en Wilkins), p. 4], totdat 'n stormloop van asteroïde-ontdekkings in die laat 1840's en 1850's sterrekundiges aangemoedig het om na hulle te verwys as 'klein planete' of 'asteroïdes' in plaas van 'primêre planete'. Olmsted het die vier nuutste planete as getalle 5, 6, 7 en 8 gehad, en Jupiter was die negende planeet. (Let op dat die ander sewe primêre planete Mercurius-Uranus was totdat Neptunus in 1846 ontdek is.) Die vooraanstaande Britse sterrekundige Sir John Herschel het in die eerste helfte van die 19de eeu 'n reeks beroemde handboeke oor sterrekunde geskryf, ook hy tel 11 planete, met Jupiter as die negende, en verwys na Ceres, Juno, Pallas en Vesta as "ultra-zodiacal planets" in sy 1833-uitgawe van 'N Verhandeling oor sterrekunde.

    Die besigheid van die "negende planeet" wat aan Pluto toegeken word, het ook historiese teenstrydighede. Baie van die voorstanders van 'Pluto-as-negende-planeet' beweer vandag dat handboeke en 'geskiedenis' nie in die geval van Pluto moet verander word nie, maar dieselfde persone lyk onbekend met die astronomiese geskiedenis voor 1930 in werklikheid, vóór Copernicus, daar was sewe verskillende "planete", en die aarde was nie een daarvan nie: die maan, die son, Mercurius, Venus, Mars, Jupiter en Saturnus - en in die antieke tyd het Apollonius van Myndos gesê dat selfs komete was volgens Seneca (Nat. Vrae. VII, 17). [Lesers wat belangstel in hierdie uitgawe van arbitrêre getalle planete in ons sonnestelsel, kan kyk na die heerlike artikel uit 1990 deur I. Bernard Cohen, "G. D. Cassini and the Number of the Planets" in Natuur, eksperiment en die wetenskappe, red. deur T. H. Levere en W. R. Shea (Dordrecht: Kluwer Academic Publishers).] As 'n interessante historiese eenkant skryf William Henry Smyth in 1844 (in 'N Siklus van hemelse voorwerpe, Vol. 1, bl. 153): "Sir William [Herschel] se eie definisie van asteroïdes is dat dit hemelliggame is wat in wentelbane beweeg waarvan die vlak geneig kan wees tot die ekliptika in watter hoek ook al, hul beweging kan direk of retrograde wees, en hulle mag al dan nie aansienlike atmosfeer, baie klein komas, skywe of kerne. ' Dit was Herschel self wat die term "asteroïdes" voorgestel het vir Ceres, Pallas, Vesta en Juno, en dit was ook Sir William (die vader van Sir John) wat Uranus aanvanklik as 'n skynbare komeet aangemeld het toe hy dit die eerste keer ontdek het.

    Freedman (op.cit.) merk op dat die sesde-graad-leerplan in sy tuisdorpskool nou krities ondersoek na Pluto se planetêre status op 'n waardevolle manier wat leerlinge en studente regtig kan leer hoe wetenskap werk. Soos blyk uit die onderstaande lys van aanhalings, kan vasgestel word hoe verouderd 'n sterrekundehandboek is of dit net Pluto verwys as die negende groot planeet wat behoorlik opgedateer is, om Pluto as lid van die klein trans-Neptuniese voorwerpe te bespreek. van die sonnestelsel, en let op dat die foutiewe kategorisering van Pluto bloot as die negende groot planeet (wat deur Lowell-sterrewag bekamp word) met die ontdekking daarvan in 1930 stadig maar geleidelik reggestel word. Pluto word eers in 1930 'n groot planeet genoem as gevolg van 'n soeke na 'n mitiese negende groot planeet wat Neptunus en Uranus kwansuis sou steur (weens die gebrek aan voldoende presiese posisionele waarnemings vir daardie reuse-planete destyds). As Pluto vandag ontdek word, sal dit hanteer word deur die Minor Planet Centre van die Internasionale Astronomiese Unie en 'n klein planeet-benaming kry, soos wat gebeur het vir die honderde ander trans-Neptuniese voorwerpe wat sedert 1992 ontdek is. Basies sou Pluto nie as 'n groot planeet as dit vandag ontdek sou word!

    In 1998 is inderdaad voorgestel dat klein planeet nommer 10000 aan Pluto toegeken word, sodat dit meer gereeld orbitale analises en nuttige astrometriese katalogisering sou kry (opgemerk in Freedman, op.cit.), maar dit wat voorgestel is, is deur talle Amerikaanse sterrekundiges (wat waarskynlik nie sou omgegee het nie) uitgeskreeu as Pluto in Europa ontdek is, 'n punt wat sommige nie-Amerikaners nie mis nie, dit lê ten grondslag van die kwessie dat politiek en nie wetenskap grootliks verantwoordelik is vir 'n druk om Pluto as "die negende planeet" te beskou. Let daarop dat ongeveer drie dosyn ander TNO's (nog nie Pluto nie) permanente "klein-planeet" -getalle deur die Minor Planet Centre (vroeg in 2003) gekry het. In 1957 het die Minor Planet Center astrometriese waarnemings van Pluto gepubliseer onder die titel "klein planete" (MPC 13)! Die pas aangenome IAU "Terms of Reference" (2000) wat die Minor Planet Center definieer, "amptelik" laat dit toe om astrometrie- en baanberekeninge vir Pluto te hanteer, en die Klein Planeet-omsendbriewe is nou geleë om sulke inligting oor Pluto te publiseer as die wêreldwye publikasie wat dit gereeld doen (dit was nodig om data oor Pluto te versamel en te argiveer).

    As dit nie as 'n belangrike planeet beskou sou word as dit vandag ontdek word nie, waarom moet ons aanhou om die dwalende aannames uit die verre verlede te aanvaar?

    Natuurlik het dit baie jare geneem nadat Copernicus in 1543 sy heliosentriese teorie gepubliseer het, voordat sterrekundiges oor die algemeen geneig was om te leer dat planete in die omgewing van die son beweeg, nie op die aarde nie. En die redes was soortgelyk aan die redes vir die noem van Pluto 'n belangrike planeet in die dertigerjare: waarnemings wat baie minderwaardig was as die waarnemings wat ons vandag het. (As Copernicus meer noukeurige waarnemings van die planete beskikbaar gehad het, sou die probleem baie vinniger opgelos word, omdat die swak aard van die waarnemings baie mense in die 16de eeu laat stilstaan ​​het met die aanvaarding van heliosentrisme.) Die politieke en sosiale druk van die Die 20ste eeu verskil in die algehele karakter nie so van die politiek en sosiale druk van die 16de eeu nie, en nog 'n paar jaar moet verbygaan voordat nuwe generasies sterrekundiges die swak logika ten opsigte van Pluto as die negende groot planeet ten volle aanvaar. Selfs Galileo (wat die sterrekunde met sy astronomiese ontdekkings in die vroeë 17de eeu met behulp van vroeë teleskope omgekeer het) kon nie die bewering van Tycho Brahe en Johannes Kepler aanvaar dat komete om die son wentel nie (Galileo volg Aristoteles se bewering dat komete deel uitmaak van ons aarde boonste atmosfeer, nader aan ons as die maan). Sterrekundiges is ook menslik, en baie van hulle sukkel om verandering te aanvaar.

    Die geskiedenis van die sterrekunde is vol voorbeelde van dinge wat as een manier beskou word en dan op 'n ander manier, met die aanvaarding van die publiek stadig omdat die status quo gemaklik is [voorbeelde sluit in die aarde wat om die son draai (in plaas van andersom) die bewegings van die planete en komete na aanleiding van fisiese wette (eerder as om "leesbare" voorspellings van gebeure op aarde via astrologie uit te spel) komete as vaste liggame (eerder as los versamelings meteoroïede) sterre as sonne in die verte (eerder as om punte op die plafon van die sonnestelsel) sterrestelsels as verre eiland "universes" soos ons eie Melkweg (eerder as newels in ons eie galaktiese heelal) ens.]. Soos Freedman (op.cit.) skryf, is die hoofuitsprake wat Pluto steeds as 'die negende planeet' beskou, diegene wat bang is vir 'veranderende geskiedenis', uit vrees dat die sterrekunde sleg sal lyk, maar hy voeg by dat geleidelike en onvermydelike universele verwerping van die konsep van nege groot planete sal die komende dekades aanbreek namate jonger sterrekundiges die oueres vervang wat nou in hierdie veld werk. Verandering is immers 'n aanvaarde deel van die sterrekunde (en alle wetenskap), en dit word selfs deur die algemene publiek verstaan ​​dat selfs die belangrikste konsepte en idees soms moet verlaat word om verder te vorder. Die redakteur van een van die wêreld se voorste wetenskaplike tydskrifte stel dit op hierdie manier: "Wetenskap is volgens sy aard 'n proses wat oop is vir die bevraagtekening en omverwerping van tans aanvaarde idees" (2005, Aard 436, 1). Inderdaad, veranderinge is reeds besig om in die denkpatroon van wetenskaplikes in die veld te vaar, soos gesien tydens die 2000 Algemene Vergadering van die Internasionale Astronomiese Unie, waar 'n informele peiling onder enkele dosyne sterrekundiges van die sonnestelsel van regoor die wêreld die volgende resultate onder die kiesers opgelewer het: diegene wat Pluto slegs as 'n groot planeet beskou, 14 persent diegene wat Pluto slegs as 'n trans-Neptuniese voorwerp (TNO) beskou en nie as 'n groot planeet nie, 24 persent diegene wat Pluto as 'dubbele status' beskou [soos (2060) = 95P / Chiron, 'n komeet wat 'n minderjarige planeetgetal as 'n Centaur gekry het] as 'n planeet en 'n TNO, 63 persent [resultate gepubliseer in Noordeligte, 24ste Algemene Vergadering van die IAU, nr. 7]. Handboeke en ensiklopedie-artikels word herskryf om die veranderende siening van Pluto te weerspieël, en die American Museum of Natural History in New York City vertoon nou korrek slegs agt hoofplanete (Mercury-Neptunus) in ons sonnestelsel.

    Selfs kort na die ontdekking was daar kommer dat Pluto nie so maklik 'n groot planeet genoem kon word nie (vanweë sy flouheid en geïmpliseerde klein grootte), insluitende gepubliseerde bekommernisse deur twee prominente skrywers oor sterrekundehandboeke. John Charles Duncan (1935, Sterrekunde: 'n handboek, 3de hersiene uitg. New York: Harper & Brothers Publ., P. 271) het geskryf dat Pluto selfs jare later "blykbaar in die klas van die kleiner planete of selfs van die asteroïdes behoort", in Duncan se 1946-uitgawe van sy handboek (p. 287), hy dieselfde standpunt behou het. Net so het Forest Ray Moulton (1931, Sterrekunde New York: The MacMillan Co., p. 244) het opgemerk: 'Miskien is [Pluto] die mees afgeleë lid van die sonfamilie, maar waarskynlik hou dit verband met die planetoïede. . . (of asteroïdes) ". En R. A. Lyttleton het in 1936 voorgestel dat Pluto 'n ontsnapte satelliet van Neptunus kon wees (MNRAS 97, 108). Dit is interessant dat die sterrekundiges van die Lowell-sterrewag ná hul aanvanklike persverklarings 'n tweede twyfel gehad het en in die openbaar aangekondig het dat hulle 'gedink het dat dit bewys kan word dat dit 'n unieke asteroïde of 'n buitengewone komeetagtige voorwerp is', dit in antwoord op 'n announcement by AO Leuschner at Berkeley that the new object could be "a large asteroid . . ., . . . one of many long-period planetary objects yet to be discovered, or a bright cometary object" due to its "high [orbital] eccentricity and small mass" --- the small mass being obvious from the object's apparent brightness and calculated large distance from the earth [New York Times, 1930 April 14, p. 23].

    Below is a partial list showing how Pluto is now described/mentioned as not being termed a "major planet" by astronomers in the scientific literature, textbooks, and popular science magazines (note that Chiron is a large comet-like minor planet that crosses the orbit of Saturn, Titan is a large satellite of Saturn, Triton is a large moon of Neptune, and Charon is Pluto's satellite). The list below is only a partial list (hopefully a realistic cross-section) of what has been published recently in terms of Pluto's non-major-planet status it is provided here by popular demand, in response to both astronomers and non-astronomers who have asked that this information be made available publicly. So, then, we find Pluto now described as follows (this list was completed in 1997-1998 and has not been updated):

    In addition, one will see that most serious discourses on the evolution of objects in the outer solar system mention crossing the orbit of Neptune, the outermost major planet (Pluto is not usually so mentioned as a reference point, for obvious reasons). See, for example, P. R. Weissman (1991, in COMETS IN THE POST-HALLEY ERA, Vol. 1, p. 477) Fernandez and Ip (1991, reference given above) G. W. Wetherill (1991, in COMETS IN THE POST-HALLEY ERA, Vol. 1, p. 539) M. J. Mumma et al. (1993, in PROTOSTARS AND PLANETS III, p. 1188). Be cautious of the reliability of any text in which the author discusses objects in the solar system "beyond Pluto".

    Getting recognition for an inflated categorization for political benefit of an individual or group (as Lowell Observatory did for Pluto in 1930) is not uncommon. Recently, Vermont politicians got Congress to recognize Lake Champlain as one of the "Great Lakes" so that Vermont could benefit from legislation directed at the Great Lakes [Seife 1998, Nuwe wetenskaplike 157(2125), 13].

    Ian Ridpath [1978, Sterrekunde 6(12), 6] put it well when he recited Abraham Lincoln's riddle, in which Lincoln asked somebody, 'If you call a tail "a leg", how many legs does a dog have?' The person offered, 'Five?', to which Lincoln replied, 'No, vier --- [merely] calling a tail "a leg" does not make it a leg!' To which Ridpath added: 'If you call Pluto "a [major] planet", how many [major] planets does the sun have?'


    First Close-up Views of Pluto

    Figure 5: Global Color Image of Pluto. This New Horizons image clearly shows the variety of terrains on Pluto. The dark area in the lower left is covered with impact craters, while the large light area in the center and lower right is a flat basin devoid of craters. The colors you see are somewhat enhanced to bring out subtle differences. (credit: modification of work by NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)

    Pluto is not the geologically dead world that many anticipated for such a small object—far from it. The division of the surface into areas with different composition and surface texture is apparent in the global color photo shown in Figure 5. The reddish color is enhanced in this image to bring out differences in color more clearly. The darker parts of the surface appear to be cratered, but adjacent to them is a nearly featureless light area in the lower right quadrant of this image. The dark areas show the colors of photochemical haze or smog similar to that in the atmosphere of Titan. The dark material that is staining these old surfaces could come from Pluto’s atmospheric haze or from chemical reactions taking place at the surface due to the action of sunlight.

    The light areas in the photo are lowland basins. These are apparently seas of frozen nitrogen, perhaps many kilometers deep. Both nitrogen and methane gas are able to escape from Pluto when it is in the part of its orbit close to the Sun, but only very slowly, so there is no reason that a vast bowl of frozen nitrogen could not persist for a long time.

    Figure 6 shows some of the remarkable variety of surface features New Horizons revealed. At the right of this image we see the “shoreline” of the vast bowl of nitrogen ice we saw as the smooth region in Figure 5. Temporarily nicknamed the “Sputnik Plains,” after the first human object to get into space, this round region is roughly a thousand kilometers wide and shows intriguing cells or polygons that have an average width of more than 30 kilometers. The mountains in the middle are great blocks of frozen water ice, some reaching heights of 2 to 3 kilometers.

    Figure 6: Diversity of Terrain on Pluto. This enhanced color view of a strip of Pluto’s surface about 80 kilometers long shows a variety of different surface features. From left to right, we first cross a region of “badlands” with some craters showing, and then move across a wide range of mountains made of water ice and coated with the redder material we saw in the previous image. Then, at right, we arrive at the “shoreline” of the great sea of frozen nitrogen that the mission scientists have nicknamed the “Sputnik Plains.” This nitrogen sea is divided into mysterious cells or segments that are many kilometers across. (credit: modification of work by NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)

    Figure 7 shows another view of the boundary between different types of geology. The width of this image is 250 kilometers, and it shows dark, ancient, heavily cratered terrain dark, uncratered terrain with a hilly surface smooth, geologically young terrain and a small cluster of mountains more than 3000 meters high. In the best images, the light areas of nitrogen ice seem to have flowed much like glaciers on Earth, covering some of the older terrain underneath them.

    The isolated mountains in the midst of the smooth nitrogen plains are probably also made of water ice, which is very hard at the temperatures on Pluto and can float on frozen nitrogen. Additional mountains, and some hilly terrain that reminded the mission scientists of snakeskin, are visible in part (b) of Figure 7. These are preliminary interpretations from just the first data coming back from New Horizons in 2015 and early 2016. As time goes on, scientists will have a better understanding of the unique geology of Pluto.

    Figure 7: Diversity of Terrains on Pluto. (a) In this photo, about 250 kilometers across, we can see many different kinds of terrain. At the bottom are older, cratered highlands a V-shaped region of hills without cratering points toward the bottom of the image. Surrounding the V-shaped dark region is the smooth, brighter frozen nitrogen plain, acting as glaciers on Earth do. Some isolated mountains, made of frozen water ice, are floating in the nitrogen near the top of the picture. (b) This scene is about 390 kilometers across. The rounded mountains, quite different from those we know on Earth, are named Tartarus Dorsa. The patterns, made of repeating ridges with the more reddish terrain between them, are not yet understood. (credit a, b: modification of work by NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)


    The Meaning

    When Uranus is conjunct Pluto a new cycle in the relationship between the human factors which these two planets symbolize begins. The cycle now ending began in 1850-51 at the time when the spread of the Industrial Revolution began to affect directly and indirectly, through colonialism, the whole of humanity. Pluto was not discovered yet, so that the factors in man which it represents had not yet emerged into man's collective consciousness. These factors, in our modem world transformed by the very technology which enabled us to discover the planet Pluto, refer to the progressive "planetarization" of mankind &mdash to whatever seeks to unite men in terms of the most basic common denominator, in terms of their most elementary common humanity.

    Unless a nuclear total war almost completely disrupts human evolution, there seems to be no doubt that a global or planetary society encompassing all human beings will take shape next century, perhaps after a period of reorganization beginning around 1989-90. Such a society is already a fact at the level of world-communication, industry and indeed of international politics. However, the Jupiterian and Saturnian traditions of our still surviving separate and proudly individualistic cultures and nations are stubbornly resisting the changes which Uranus has brought to us since it was discovered late in the 18th century. Uranus by itself can only start the process of transformation. This process needs also the operation of other factors represented by Neptune and Pluto. Thus the cycles of relationship linking these three planets are most important. Every conjunction begins a new cycle.

    There was a conjunction of Uranus and Neptune at Capricorn 2°59' on March 22nd, 1821 (near the time of the death of Napoleon) the next one will occur on the 19th and 20th degrees of Capricorn in 1993. In 1821 Neptune had not yet been discovered, just as in 1850 Pluto was still unknown when Uranus came in conjunction to it in the last degrees of Aries. Thus one might say that a fully conscious awareness of the great process of all-human planetary change which began in the 18th century will not take place until 1993 when Uranus begins its new cycle with Neptune. What is happening today, as Uranus starts its new cycle of relationship with Pluto, is that the very foundations of man's collective mentality are being transformed for Pluto represents indeed the planetary aspect of mind, the one mind of Man.

    Many psychological or para-psychological mysteries would be explained if one really understood that there is but one mind &mdash that humanity is, at the mental level, one vast organized system. This concept is not new. It was formulated in old India under the more or less mythological symbolism of the Manus, who are not to be considered as personages but rather as different aspects of the collective mind of Man. The French archaeologist and philosopher Teilhard de Chardin, whose long suppressed writings are today being read all over the globe, spoke of the "noosphere" in much the same sense as I am speaking of the one mind of humanity.

    The nervous system of every individual person is like a radio tuned up differently to this one mind. Some individuals have a very poor radio able to release only one limited type of thought. Others possess an exceedingly sensitive radio-apparatus able to tune in to many frequencies. Still others are sensitive, but the radio waves of different frequencies tend to get mixed up, and mental confusion is the result. The brain-radios can transmit as well as receive so that the noosphere (mind), is as complex a realm as the biosphere (life), the realm where all living organisms on earth act and interact under the compulsive urges of life.

    This realm of life is essentially operating, through the element, water. Life began in the sea. When understood in its collective rhythms, it has much to do with Neptune. Most of the human body is actually sea water, and excellent results have been obtained in Europe by injecting purified sea water into a man's veins. A whole system of healing, thalassotherapy, is being developed, including hot sea water baths with massage, and so on. It is also being discovered, mainly by a great Italian scientist, Piccardi, that it is by the intermediary of water that still unknown cosmic energies act upon all living organisms and some colloidal substances &mdash a discovery which indirectly supports my often repeated assertions that astrology is a Neptunian, and not a Uranian way of thinking.

    As I see it, the conjunction of Uranus and Neptune in 1993, ending a strong planetary emphasis in the sign Capricorn in 1989-1990, should see the start of a deep transformation of life on earth. The present conjunction of Uranus and Pluto is witnessing the definite beginning of a radical transformation of the one mind of humanity, which is also the mind of this planet, Earth, in which we move, live and have our being.

    The conjunction of Uranus and Neptune in 1821 and of Uranus and Pluto in 1850-51 paved the way, as it were, for what has been slowly unfolding until now. These two cycles were preludes they marked critical states, the periods of transition between the old and the new. Now the real thing is about to happen, and obviously many people will not like it. The institutionalized minds of political leaders, university regents and boards of trustees or directors will fight against the change, just as classes and groups owning privileges and special positions have always fought against inevitable social, political and cultural changes. But the new always wins in the end, tragic as may be the victory.

    It is therefore futile to think of catastrophes ahead because of the rather crucial planetary aspects of these years 1965 and 1966: The only real catastrophe would be if nothing at all happened &mdash for this would imply that man's capacity for growth has become ankylosed! But, even if this were the case, I believe that the planet itself would rise and shake man loose in some very radical manner, just as a human body can react violently and shake loose its mind, when the latter has become rigid and unyielding. We speak today of psychosomatic illnesses but there are also illness which are somatopsychic, in the sense that they constitute a revolt of the body against a perverted or catatonic mind.

    Pluto, I repeat, refers to the collective mind of humanity. In a narrower sense it refers to some closely interrelated and authoritarian human groups &mdash to modem gangs and totalitarian regimes, for in these tight human groupings only one kind of mentality is allowed. If left alone Pluto tends to level down to the most basic common denominator. It is the symbol of depth, and in a sense of the core of things, for at the earth's core everything that is subject to gravitation becomes compressed into unity. But when Uranus acts upon Pluto (and of course there is always such an action, but more or less focused and operative), Uranus does not allow Pluto, as it were, to pull everything to the bottom or core. Uranus periodically fecundates and always stirs up the realm of Pluto and we are witnessing such a fecundation.

    Unfortunately perhaps it occurs in opposition to Saturn's place in Pisces, so that we are witnessing a strangely disturbing tug-o-war opposing a revolution in the depth of Man's mind to the solidified remains of the past. The square of Jupiter to Saturn in a sense helps forces of progress by focusing internecine conflicts within the realm of obdurate conservatism and tradition. The disturbance is planetary-cosmic as well as social-cultural in meaning.

    What actual events will release the pressures being built up no one really can tell, so complex the situation is but the heliocentric picture of the solar system for this fall and early 1966 seems to show that there will be forces at work which have the whole solar system for their field of operation, particularly during November &mdash perhaps even as early as September. It may be interesting to note that in the remarkably significant Sabian system of symbolism for each zodical degree, the 18th degree of Virgo, on which Uranus and Pluto meet this October 9th, is represented by "An ouija board," while the symbol for the 17th degree on which the two last conjunctions occur is "A volcano in eruption." Pluto was on this 17th degree from November 14th, 1964, to January 23rd, 1965 it reaches it again on September 6th, 1965, and on March 15th and June 20th, 1966. The ouija board symbol might be quite revealing, for the October 9th conjunction on the 18th degree of Virgo could open the door to a new approach to psychology and para-psychology which might revolutionize further our realization of the nature of mind. Such a revolution seems relatively imminent, though most official institutions of learning will probably oppose it.


    Why was Pluto's resonance not discovered until 1965? - Sterrekunde

    Sensemaking Checklist

    Teachers and families across the country are facing a new reality of providing opportunities for students to doen science through distance and home learning. Die Daily Do is one of the ways NSTA is supporting teachers and families with this endeavor. Each weekday, NSTA will share a sensemaking task teachers and families can use to engage their students in authentic, relevant science learning. We encourage families to make time for family science learning (science is a social process!) and are dedicated to helping students and their families find balance between learning science and the day-to-day responsibilities they have to stay healthy and safe.

    Interested in learning about other ways NSTA is supporting teachers and families? Visit the NSTA homepage.

    Sensemaking is actively trying to figure out how the world works (science) or how to design solutions to problems (engineering). Students doenscience and engineering through the science and engineering practices. Engaging in these practices necessitates students be part of a learning community to be able to share ideas, evaluate competing ideas, give and receive critique, and reach consensus. Whether this community of learners is made up of classmates or family members, students and adults build and refine science and engineering knowledge together.

    Introduction

    Today's Daily Do, Why isn't Pluto a planet anymore?, is inspired by astronomers Jane X. Luu and David C. Jewitt's discovery of the Kuiper Belt for which they were awarded the 2012 Kavli Prize for Astrophysics. NSTA is excited (dare we say, over the moon) and honored to welcome Jane Luu as The Kavli Foundation keynote speaker at the Engage: Fall20 Virtual Conference. Join us for her live presentation, The Story of Pluto and the Kuiper Belt: How Science Progresses, on Saturday, November 14, 2020, at 11:05 am ET. It's not too late register!

    The reclassification of Pluto followed a vote on the first formal definition of a planeetat the 26th General Assembly of the International Astronomical Union (IAU) on August 24, 2006. Fourteen years after Pluto's demotion from full-fledged planet to dwarf planet, many people are still in mourning. But did you know Pluto isn't the first celestial object to loose it's planet status in our solar system? In today's Daily Do, students frame their thinking with patterns as they engage in science and engineering practices and confront the nature of science to answer the question, Why isn't Pluto a planet anymore?

    A Plan or Map of the Solar System projected for Schools & Academies (1846)

    Experience the Phenomenon

    Tell students you have a puzzling phenomenon to share! Ask students to create a space in their science notebooks to record observations and questions that come up. Share the A Plan or Map of the Solar System projected for Schools & Academies with students (either project the image or share the link with students so they are able to zoom in on different parts of the map). Indicate to students the map represents the planets known in our solar system in 1846.

    Note to Educators: Ceres, Pallas, Juno and Vesta were identified as planets upon their discovery (1801, 1802, 1804 and 1807, respectively). While astronomer William Herschel, famous for his 1871 discovery of Uranus, advocated to reclassify these celestial objects into a new class of rocky objects - asteroids - as early as 1802, they seem to have maintained their status as planets until at least the mid-1840s (sources vary on this point). NASA Science Solar System Exploration cites 1863 as the year Ceres was widely accepted as an asteroid among astronomers.

    Provide students time in the Alone Zone (independent thinking time) to make and record observations. Students will likely have a range of knowledge of the solar system. Encourage students more familiar with the solar to notice what's included on the map and not "what's missing" from it. Refrain from answering individual questions instead direct students to record their questions in their science notebooks.

    Next, ask students to turn to a partner and share observations. As you move around the room, listen for students to describe some or all of the following observation:

    • there are 12 planets
    • three planets, Uranus, Saturn and Jupiter, are much larger than the rest
    • Vesta is the smallest planet
    • Vesta might be an asteroid (orbit is labeled asteroid)
    • the three largest planets are furthest from the Sun
    • four planets have moons
    • one planet has rings
    • 98 comets (comet sightings) are recorded
    • one comet path (orbit) is shown
    • Saturn and Uranus have the most moons (6) and Earth has the least (1)

    Ask students to share their observations with the class, first calling on one of the student pairs who shared their noticing of 12 (or maybe 11) planets. Create a class record of observations. Students may have many questions about the map either create a class list or ask students to make sure to record them in their science notebook.

    Tell students you have another solar system map you need to share with them - Rand McNally's Modern Space Map published circa 1950. Again, project the map or share the link with students. This time, ask students to work in pairs to make and record observations. Remind them not to worry about what's not on the map, but to notice what's included. Encourage them to continue to record questions as well.

    Rand McNally's Modern Space Map (c. 1950)

    Assign pairs to form groups of four students. Ask them to first share their noticings with each other. As you move around the room, help keep students focused on sharing observations of the Modern Space Map and not (yet) comparing the two maps. You might ask students to use the talking stick protocol described in the Why are plane designs so different? Daily Do.

    Next, ask the groups to work collaboratively to identify and record differences between the two maps. Listen specifically for groups to talk about the the absence of Vulcan van die Modern Space Map, die appearance of the planets Neptune and Pluto, Ceres identified as an asteroid (Pallas, Vesta and Juno are not labeled), and the notation "1,500 to 50,000 known" with regards to the number of asteroids . When you bring the class back together to share the differences between A Plan or Map of the Solar System projected for Schools & Academies en Modern Space Map, make sure to call on these groups first. Record these differences and any others the groups have identified.

    Ask students to review the questions they recorded in their notebook and add new questions they have about observations of and/or differences between the two solar system maps. Which three questions about the phenomenon of the changes in the solar system maps between 1846 and 1950 are the most puzzling to them? Ask students to share these questions with their group and note the two most common questions and the one question the group votes is the most intriguing or unique. Bring the groups together to share these three group-selected questions with the class. Students will likely ask

    • What happened to planet Vulcan?
    • Why was Ceres changed from a planet (1846) to an asteroid (c. 1950)?
    • What happened to Pallas, Vesta and Juno? (Are they classified as asteroids like Ceres or did they disappear like Vulcan?)
    • Why is Ceres (and Eros) shaped like a (rolling pin, sea shell, etc.)? Are all asteroids shaped that way?
    • Why is Eros labeled on the Modern Space Map and not Pallas, Vesta and Juno? Is Eros bigger than them?
    • How are new planets discovered?
    • Why does the comet's path cut across the paths (orbits) of the planets? (Why isn't it's path parallel to the orbits of the planets?)
    • What are sun spots?

    If students don't ask about Ceres (and Pallas, Vesta and Juno), you might direct their attention to A Plan or Map of the Solar System projected for Schools & Academies en Modern Space Map and ask, "Why do you think Neptune and Pluto are not included on the 1846 map?" Students will likely say they weren't discovered yet. Then point out Ceres, Pallas, Vesta and Juno and say, "These planets were already discovered in 1846. Why do you think they are not included on the Modern Space Map? Were they undiscovered?" Students will (most likely) unanimously agree a planet can't be undiscovered, but may share many different ideas about why Ceres, Pallas, Vesta and Juno aren't included as planets on the c. 1950 map. Point out these differences and ask, "We have a lot of ideas about why these celestial objects aren't included as planets on the Modern Space Map. We see Ceres classified as an asteroid (and presumably Pallas, Vesta and Juno). Should we investigate what changed between 1846 and 1950 that caused astronomers to demote Ceres and the other objects from planets to asteroids?"

    Why wasn't Ceres a planet anymore?

    Tell students you have data to share for the planets identified on each map. Share the Data for Planets Identified on Solar System Maps link with students. This will enable them to make a copy of the Excel file which contains Table 1. Planets Identified on A Plan or Map of the Solar System Projected for Schools and Academies (1846) and Table 2. Planets Identified on Rand McNally's Modern Space Map (c. 1950). Sharing the Excel version of the data tables allows students to easily sort data which may help reveal patterns. (PDF versions of the data tables can be found in the Why isn't Pluto a planet anymore? collection of resources.)

    Say to students, "These are the data astronomers had available to them - in addition to the data contained on the maps - to reach consensus on reclassifying Ceres, Pallas, Vesta, and Juno from planets to a new class of rocky celestial objects called asteroids." You might further share that astronomer William Herschel proposed this new class of objects when Pallas was discovered he was an early advocate for "demoting" Ceres, Pallas, Vesta and Juno from planet status.

    You may need to share with middle school students that eccentricity is a measure of how close a planet's orbit is to a perfect circle. The closer the eccentricity is to 0.0, the closer it is to a perfect circle.

    Students might ask you the difference between the two classifications make sure to let them know formal definitions for neither planete nor asteroïdes existed during this time period. Put the question back to students, "How might you decide how to categorize the celestial objects represented as planets on the 1846 map?" Students will likely say look for patterns (similarities and differences) in the data.

    Ask students to work in the Alone Zone to identify patterns in each of the two data sets and between the two data sets. Encourage students to sort the data in a variety of ways to see if any patterns emerge. As you move around the room, you might ask students some or all of the following questions:

    • What are some similarities and differences among the data in Table 1? Table 2? Between Table 1 and Table 2?
    • What is one way you could classify or group these objects identified as planets on Table 1, to create groups of planets and asteroids that are similar to each other?
    • What attributes (characteristics) are you using to classify the planets and asteroids?
    • Follow up question: To which of your groups would a celestial object with the following characteristics belong: 18% the size of Earth, orbital inclination of 0.9 degrees, and 0.210 eccentricity? What other data would you want or need to help classify the object?

    Next, move students into small groups of three or four students. Ask students to share patterns they noticed with their group. You might ask the groups some of the same questions you asked students as they worked independently to identify patterns. Encourage students to consider their observations of the two solar systems maps to support or refine the patterns they identified.

    Bring the groups back together. Ask students, "How do you think astronomers used these data to support the argument for reclassifying Ceres, Pallas, Vesta and Juno from planets to asteroids?" Support a class consensus discussion using some or all of the following prompts:

    • What is our evidence for reclassifying Ceres (Pallas, Vesta and Juno) from a planet to an asteroid?
    • Both groups seem to be using the term asteroid/planet but in a different way, could someone explain the difference?
    • Would anyone have put this point in a different way?
    • What ideas are we in agreement about?
    • Is there more evidence or clarification needed before we can come to agreement? What is that?

    Refer students back to the class list of questions. Are there any other questions we can now answer? Are there any new questions we need to add to our list?

    Students may pose some of the following new questions:

    • Why was Pluto considered a planet in the 1950s when Ceres was not?
    • Why did scientists think planet Vulcan was there in the first place?
    • Why do the planets have different tilts (orbital planes)?
    • Why do the planets have different eccentricities?
    • Why is Mercury considered a planet?

    Table 1. Planets Identified on A Plan or Map of the Solar System Projected for Schools and Academies (1846)

    Table 2. Planets Identified on Rand McNally's Modern Space Map (c. 1950)

    Reflecting on the Nature of Science

    Say to students, "Arguing from evidence to support reclassifying Ceres (and Pallas, Vesta and Juno) from planet to asteroid, you acted, thought and talked as scientists. Let's take a little time to reflect on this process of science."

    Instruct students to record the following three prompts in their science notebook:

    • How did I experience science findings are frequently reinterpreted based on new evidence?
    • How did I experience scientific explanations are subject to revision and improvement in light of new evidence?
    • Based on my experience, how do science and technology drive each other forward?

    Ask students to independently reflect on the lesson and then respond to each prompt using words, pictures and/or symbols to record relevant evidence from their experience.

    Next, give students an opportunity to share their reflections with a partner. As you move around the room, listen for students to share ideas you feel would help deepen the class' understanding of the nature of science. When you bring the class back together, call on these students to share their ideas first. Before moving forward with the lesson, reiterate science is a dynamic process that never concludes, which is why scientific knowledge is open to revision in light of new evidence.

    Note to Educators: The student prompts represent elements of Understandings about the Nature of Science (NGSS Appendix D: The Nature of Science) and Interdependence of Science, Engineering, and Technology (NGSS Appendix J: Science, Technology, Society, and the Environment). Although the prompts represent elements in the 6-8 grade band, high school students may need the opportunity to develop these ideas to build the foundation for the 9-12 grade band elements.

    Why isn't Pluto a planet anymore? (And why is Ceres no longer an asteroid?)

    Ask students to recall the characteristics they used to classify celestial objects as planete en asteroïdes using the data available to astronomers in the 1950's. Why didn't Pluto and Ceres fall into the same category? Ask students to turn and share their thinking with a partner and encourage them support their ideas with relevant evidence from that data. You might ask for three or four shares from the class. Students might say:

    • Ceres (and Pallas, Vesta, and Juno) is under 10% of Earth's size and Pluto is over 10%
    • Ceres is shaped like a rolling pin (according to the Modern Space Map) and Pluto is round
    • Ceres is orbiting the Sun with 1,500 to 50,000 other objects like it (according to the Modern Space Map) and Pluto is by itself (according to the Modern Space Map)

    Share with students that on August 24, 2006, the 26th General Assembly of the International Astronomical Union (IAU) voted on the first formal definition of a planeet. As a result, Pluto was demoted from planet to dwarf planet while Ceres rose in stature from asteroid to dwarf planet. (Do not share the definition of a planet at this time.)

    Ask students, "What questions does this raise? Turn and share one new question you have with a partner." Then ask students, "How many of you are wondering why there wasn't a definition of planet before 2006 or something similar?" Many students will likely raise their hands.

    Tell students, "Before we learn the formal definition of a planet, should we find out what changed between the 1950's and 2006 that created the need for a definition?"

    The Search at the Edge of the Solar System

    Inform students you are going to share the Tumble Science podcast, The Search at the Edge of the Solar System. (Tumble Science is billed as a podcast for kids, but this interview with astronomer Jane Luu is appropriate for all ages.)

    Read or share the description of the podcast with your students:

    Is there a hard edge to the solar system? This question led to a big, breakthrough discovery that changed the way we picture the solar system - and every other solar system in the universe. The Kuiper Belt is a gigantic field of small, icy objects beyond Neptune, “planet scraps” left over from the formation of the planets. For many, many years, no one believed it might exist. Until astronomers Jane Luu and David Jewitt decided to see what was out there. Jane Luu tells the story of how she helped discover the Kuiper Belt.

    Before playing the episode, tell students to find their reflection on the process of science and review the prompts. Ask students, "As you listen to Jane Luu, think about how she might respond to these same prompts. Jot your ideas in your science notebook."

    Play The Search at the Edge of the Solar System episode for your students (02:05 - end). Depending on the age of your students, you might choose to pause at the following times and check for students' understanding:

    • 05:26 - In the 1980's, what did most people think was found beyond the orbit of Neptune? How does this compare with the data represented on the Modern Space Map c. 1950?
    • 09:10 - What kept Jane Luu and Dave Jewitt from giving up their search for faint objects beyond the orbit of Neptune?
    • 11:40 - Show students Jane Luu and Dave Jewitt's images of the Kuiper Belt object they discovered (below).
    • 15:25 - How did Jane Luu and Dave Jewitt's discovery of the Kuiper Belt change our scientific knowledge of the solar system?

    At the end of the podcast episode, provide students an opportunity to share their ideas about how Jane Luu might respond to the prompts about the process of science with a partner or small group. Bring the class back together consider using the questions above to engage the class in a discussion about how the discovery of the Kuiper Belt revised scientific knowledge about the solar system.

    Jane Luu and David Jewitt's discovery of the first Kuiper Belt Object (1992) NASA Map of the Outer Solar System (2015)

    The Story of Pluto and the Kuiper Belt: How Science Progresses

    Join us for Jane Luu's live presentation, The Story of Pluto and the Kuiper Belt: How Science Progresses, on Saturday, November 14, 2020, at 11:05 am ET (it's not too late register!) and then come back here for the final piece of this lesson.

    Acknowledgement

    Die Why isn't Pluto a planet anymore? Daily Do was made possible with generous support from The Kavli Foundation, "dedicated to advancing science for the benefit of humanity, promoting public understanding of scientific research, and supporting scientists and their work."

    NSTA has created a Why isn't Pluto a planet anymore? collection of resources to support teachers and families using this task. If you're an NSTA member, you can add this collection to your library by clicking Add to my library near the top o the page.

    The NSTA Daily Do is an open educational resource (OER) and can be used by educators and families providing students distance and home science learning. Access the entire collection of NSTA Daily Dos.


    Why was Pluto's resonance not discovered until 1965? - Sterrekunde

    The smallest of the nine planets, Pluto also has the largest average distance from the Sun. Pluto's orbit is highly inclined to the ecliptic plane. Its orbit is also highly elliptical, bringing it closer to the Sun than Neptune from Feb. 7, 1979 to Feb. 10, 1999. Pluto was discovered by Clyde Tombaugh on Feb. 10, 1930, but not announced until March 13. For a personal account of the extent of this survey, see Sky & amp Teleskoop (Apr. 1991).

    At 43 K, Pluto's surface consists of frozen methane, ammonia, and water. Mutual occultation of Pluto and its only moon Charon occurred from Dec. 1984 to Sept. 23, 1990. The alignment, in which Charon's 6.39 day orbit appears edge-on from the earth, only happens every 124 years. A discussion of the occultations can be found in Sky & amp Teleskoop (Jan. 1991, p. 13) and Sky & amp Teleskoop (Sept. 1987). The first image resolving Pluto and Charon was taken by the Hubble Space Telescope. In the image appearing on Sky & amp Teleskoop (Jan. 1991, p. 16), the bodies are separated by 0.9".

    "Plates, Pluto, and Planet X." Sky & amp Teleskoop, 360-361, Apr. 1991.

    Sky & amp Teleskoop, 248, Jan. 1987.

    Sky & amp Teleskoop, pp. 13-16, Jan. 1991.

    Arnett, W. "The Nine Planets: Pluto and Charon." Nine Planets.

    Levy, D. H. "A Planet By Any Other Name." Parade Magazine, pp. 10-13, May 30, 1999.

    Stern, S. A. and Tholen, D. (Eds.). Pluto and Charon. Tucson, AZ: University of Arizona Press, 1997.


    Kyk die video: Hoe Groot is de grooste ster? (November 2022).