Sterrekunde

Het u foto's wat die maanverskil tussen suidelike en noordelike waarnemers toon?

Het u foto's wat die maanverskil tussen suidelike en noordelike waarnemers toon?


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Aangesien waarnemers in verskillende dele van die aarde die maan in effense verskillende hoeke in vergelyking met die aarde sal waarneem (kies verwysingsvektor: noordpool, oorsprong van die lengte-posisie van die breedtegraad, wat ook al), sal hulle heel effens verskillende gesigte van die maan waarneem.

Ek het aanlyn probeer kyk of iemand voorbeelde van foto's van die maan op dieselfde tyd uit verskillende dele van die aarde gehad het, maar was oorweldig deur foto's wat wys dat die maan in die suidelike halfrond "onderstebo" voorkom in vergelyking met wat 'n noordelike waarnemer sou doen. verwag en kon niks vind nie.

Het of weet iemand waar om 'n voorbeeld te kry van wat ek vra? Let daarop dat ek nie vra ek na die "onderstebo" maan-effek wat ek so pas beskryf het, en ek vra ook nie oor maanvibrasie nie: ek vra spesifiek of ek effens verskillende gesigte van die maan kan waarneem, bloot deur êrens anders op aarde te staan ​​as iemand anders op dieselfde tyd.


Dit is vals & # 33

Ek het die grootste deel van die dag my 8 "SCT buite op my grasperk gehad vir die laaste vervoer van Mercurius. Het nie een buurman gevra wat ek doen nie.

"Ek kyk na die SON! Deur 'n teleskoop !!" (en natuurlik 'n sonfilter).

# 77 darthteddy93

Ek reik die afgelope paar jaar maandeliks uit by Griffith Observatory (voor die pandemie) en dit is altyd interessant om te sien watter soort reaksies ek kry. Gewoonlik as mense sê: "Is dit regtig?" of iets in die lyn, dit is altyd uit verwondering of verbasing omdat hulle nog nooit iets deur 'n teleskoop gesien het nie. (gewoonlik kry Saturnus en die maan die reaksies). Wat meer algemeen is, is die maanverslappers wat ten minste weet dat hulle na die regte maan kyk en ek kry dit nie eens baie gereeld nie.

Gelukkig het ek net 1 plat ore gehad wat nie lank vasgehou het nie.

Ek gee beslis nie om om my oculare uit te haal of iemand die binnekant van my teleskoop te wys om te wys dat ek niks wegsteek nie, maar die behoefte het nog nie opgekom nie.

# 78 Ittaku

'N Vriend het gesê dat hy 'n eerstejaar-sterrekunde-klas geneem het en een student het eerlik gevra waarom die sterre nie voor die maan verskyn nie.

# 79 Michael Covington

Ek is gevra of ons die maan in die lug sal sien tydens 'n totale sonsverduistering. "Ja, dit is net daar, voor die son!"

# 80 Xyrus

Ek het die grootste deel van die dag my 8 "SCT buite op my grasperk gehad vir die laaste vervoer van Mercurius. Het nie een buurman gevra wat ek doen nie.

"Ek kyk na die SON! Deur 'n teleskoop !!" (en natuurlik 'n sonfilter).

Moenie met die oorblywende oog na die son kyk deur die teleskoop nie.

# 81 JeremysArt

Dit verbaas my regtig om te hoor dat soveel mense berig dat die eerste keer dat kykers 'Dis vals!' of iets in daardie mate. Ek bedoel, persoonlik, vind ek verbasend wat ek sien, maar ek is bekommerd dat die gemiddelde persoon wat hom waarskynlik van kleurryke verbeeld, super van naby hubble beelde soos gesien in handboeke, net sou dink dat dit nie so indrukwekkend is nie . Op sy beste kan Jupiter en Saturnus so groot soos 'n knoppiebattery gesien word, miskien 'n sent of sent op 'n goeie nag met 'n groot vergroting.

MAAR tot my verbasing (as iemand wat vandag 'n teleskoop besit vir een maand) is die mees algemene reaksie wat ek kry: "Sjoe!", "Dit is wonderlik!" "So cool!", En het selfs 'n "Dit is lewensveranderend." - gesien deur 'n 10 "dobbel met 10mm plossl.

Die ding wat my die meeste irriteer, is die generiese opmerkings wat mense maak as ek oor my omvang praat of foto's wys "Ek wed dat jy die bure **** regtig goed kan sien met hierdie harhar" .. of "kan jy die vlag op die maan? ' .. soos kom, is dit die 5de graad?

Geredigeer deur JeremysArt, 22 Augustus 2020 - 12:56.

# 82 Michael Covington

Sommige mense wonder eintlik wat sou gebeur as ek my teleskoop op 'n buurman se huis sou rig, en die antwoord is dat dit buite fokus sou wees, en as dit in fokus sou wees, sou ek so 'n klein area sien dat ek nie ' t iets noemenswaardigs sien nie. (Byvoorbeeld, die helfte van 'n baksteen in 'n baksteenmuur.) Ek kan dit demonstreer deur na my eie skoorsteen te wys.

[Ek dink ek het bedoel om dit in 'n ander draad te plaas, maar dit lyk asof dit net so goed in hierdie wilde draad pas soos oral. Indien nie, is die moderator welkom om dit te verwyder, of selfs uitvind waar ek gedink het ek sit dit!]

Geredigeer deur Michael Covington, 22 Augustus 2020 - 22:25.

# 83 chantepierre

Probeer die planete gister wys voor die wolke inrol. die wolke rol, maar die buurman oorkant die straat sien ons en kom vra wat ons doen.
"Ons sou die planeet Saturnus sien"
Hy lag regtig hard en sê «Maar dit is al 5 jaar gesluit! », Juig en loop weg en wens ons 'n goeie nag toe.

Inderdaad, 'n multimedia-winkel twee minute ver in die rigting waarna ons gewys het (DVD-spasies, LCD-skerms, ens.) Genaamd "Planet Saturnus" is 5 jaar of so gelede uitgekoop en hernoem!

Geredigeer deur chantepierre, 22 Augustus 2020 - 17:28.

# 84 jcastarz

Ons hier op Cloudy Nights * weet * baie oor astronomie wat ons as vanselfsprekend aanvaar - maar vergeet soms dat besoekers aan ons stokperdjie dalk nie ons perspektief deel nie.

Ek het een aand 'n paar DSO's vir 'n besoeker by 'n sterpartytjie gewys, en hy was. saggies geïnteresseerd. Uiteindelik het hy sy gedagtes uitgespreek: "wel, kan ons kyk na sommige met die helder kleure?" En toe het dit tot my deurgedring dat - alhoewel * ek * nog altyd die verskil tussen HST-beeldmateriaal en die okularisasie in 'n 8 "newt geken het, baie mense aan wie ek deur die jare dinge gewys het, dit miskien nie verstaan ​​het nie.

Ek wil nou probeer om die verskil te verduidelik tussen wat ek in my omvang toon en al die glansfoto's wat die besoeker waarskynlik op die internet gesien het.

Uit my eie ervaring: Jupiter en Saturnus verkoop oor die algemeen baie makliker aan besoekers, terwyl DSO's meer 'n aangeleerde smaak is.

# 85 vaandrig

Ja, dit is waar. Toe hy sonvlekke aan dieselfde geestelikelede wys, het hulle beweer dat hulle dit nie sien nie. Daar word nou gedink dat hulle dit waarskynlik nie gedoen het nie omdat die fokus op sy teleskoop te grof was om die regte aanpassings vir hul sig aan te bring. Miskien het hulle tog die waarheid gepraat.

Dit is 'n redelike weddenskap dat hulle nie 'n volle diafragma (alle sentimeter daarvan) sonfilter gebruik het nie. Geen wonder dat Galileo uiteindelik blind geword het nie.

# 86 vaandrig

Oorweeg dit hierdie! & gt & gt & gt

Die oplosbaarheid van 'n groot teleskoop onder groot omstandighede met groot oë. oorskry selde 500x, en meer dikwels net die helfte daarvan.

Die oplosbaarheid van 'n groot mikroskoop onder groot omstandighede met groot oë. oorskry selde 500x, en meer dikwels net die helfte daarvan.

En dit is nog net een bewys dat ons mense te midde van die universeel relevante logaritmiese grootte skale woon. Kwarks naby die Lilliputian extremum en galaktiese superclusters naby die Brobdingnagian extremum --- met ons plof reg in die middel. Soortgelyke argumente rakende die bierf Plank Time, die ouderdom van die heelal en ons lewensduur. weer, net daar in die middel. 'N Mens kan sterk argumenteer dat dit 'n noodsaaklike voorwaarde vir 'n intelligente lewe is: om ons in die middel van die ruimtetyd te bevind, met genoeg geskiedenis en fyn korrelstruktuur om te bestaan, en ook genoeg ruimte en toekoms om dit alles te begryp. Antropiese bewyse van ons bestaan, en 'n gedagtegang. oor hoe en waarom. Tom

En volgens John Lennox, 'n wiskundeprofessor in Cambridge, is mense ongeveer halfpad tussen 'n atoom en 'n sterrestelsel.

# 87 TOMDEY

En volgens John Lennox, 'n wiskundeprofessor in Cambridge, is mense ongeveer halfpad groot tussen 'n atoom en 'n sterrestelsel.

En die Higgs. hou dit alles lank genoeg bymekaar om saak te maak. Dit is +1 gelykheid nodig om sy towery te bewerk!

Toe ek nog 'n kind was, het ek op hierdie interessante manier ontdek dat rubberbande in 'n sak verkies om op hulself te vou. en hoekom die geneigdheid & gt & gt & gt Dit is inderdaad 'n pariteitseienskap!

Aangehegte kleinkiekies

# 88 rekokich

En volgens John Lennox, 'n wiskundeprofessor in Cambridge, is mense ongeveer halfpad groot tussen 'n atoom en 'n sterrestelsel.

Nie eers op 'n afstand naby die middel op lineêre of logaritmiese skale nie. En tog bestaan ​​daar mense.

# 89 bjkaras

As u dit kan doen na u eerste blik op Saturnus, is u redelik dood vir die wêreld. Ek sien die reaksie dikwels met betrekking tot voorwerpe in die hemelruim, maar nie met betrekking tot Saturnus of die maan nie.

Ek dink 'n deel van die rede hiervoor is dat ons samelewing mense ongevoelig gemaak het. Mense word oral blootgestel aan uiterstes: TV, films, videospeletjies, die nuus. As hulle iets wonderliks ​​soos Saturnus, Jupiter of M-42 sien, registreer dit net nie. Niks doen nie. As dit aanhou, sal ons 'n samelewing van hommeltuie word.

# 90 Shane Stroud

Volwassenes doen dit soms, maar ek werk baie tyd saam met Cub Scouts. Ek kry nooit volslae ongeloof van kinders nie. Daardie 'kinderagtige wonder' is ongelooflik om te sien, en laat my steeds glimlag. Ek geniet dit baie om die 'ooooh' of 'aaaah' te hoor van 'n kind wat nog nooit voorheen deur 'n teleskoop gekyk het nie.


Het u foto's wat die maanverskil tussen suidelike en noordelike waarnemers toon? - Sterrekunde

Verander die hoek van die maan se halfmaan ten opsigte van die horison deur die nag?

Ja, dit lyk asof die maan se halfmaan gedurende die dag verskillende rigtings wys omdat dit altyd na die son wys. Ek het twee foto's van die planetariumprogram aangeheg om u te wys hoe 'n sekelmaan met sonsondergang kan lyk, en dan 'n rukkie later wanneer dit gaan sak.

Hierdie bladsy is laas op 18 Julie 2015 opgedateer.

Oor die skrywer

Everett Schlawin

Everett se navorsingsfokus is op buite-son planete of eksoplanete. Dit is die planete ver buite Neptunus en Pluto, wat om ander sterstelsels wentel. Hy neem die atmosfeer van die eksoplanet waar om hul samestelling te leer. Die kleure van 'n absorberende eksoplanetatmosfeer vertel sterrekundiges waaruit die atmosfeer bestaan, daarom gebruik hy spektrograwe om die kleure van hierdie ster-planeetstelsels te verdeel en af ​​te lei watter gasse die atmosfeer vorm. Hy bou ook 'n nuwe infrarooi spektrograaf om saam met die TripleSpec 4-span op die Blanco-teleskoop in Chili te gaan.


Die Groot 5 van die Suidelike Hemel

Die mees skouspelagtige diep lugteikens van die suidelike halfrond, volgens ons beskeie mening, is van die mooiste en ontsagwekkendste voorwerpe beskikbaar vir amateursterrekundiges en astrofotografe. Sit dit op u emmerlys om te kom kuier!

1. Melkweg Galaxy Core

Die volle galaktiese middelpunt van ons Melkwegstelsel is sigbaar vir waarnemers op die suidelike halfrond. Alhoewel 'n gedeelte daarvan ook op die laer-noordelike breedtegrade sigbaar is en die suidelike horison wei, strek die hele ding in al sy glorie hoog bo-oor vir diegene in die suidelike halfrond. Die galaktiese kern styg vroeg in die oggend in die ooste / suidooste middel Maart en verskyn vroeër in die nag oorhoofs soos die seisoen vorder. Aangesien dit die swaartepunt van ons sterrestelsel is, het dit die grootste konsentrasie sterre, stof en kosmiese gasse wat almal om 'n supermassiewe swart gat wentel en dit is 'n gesig om te sien. Die melkweg lyk die helderste naby die konstellasies Boogskutter, Skerpius en Ophuichus.

Beste besigtigingstye: April - Oktober

2. Steenkool newel (Caldwell 99)

Die mees prominente donker newel aan die suidelike hemelruim, teen die ryk sterrevelde naby die Suiderkruis, is op donker plekke maklik met die blote oog sigbaar. Die Steenkoolnevel lê in die sterrebeeld Crux en is skynbaar 'n enorme donker newel ongeveer 600 ligjaar van die aarde af. Die Coalsack is nie heeltemal swart nie. Dit het 'n dowwe gloed wat afkomstig is van die weerkaatsing van die sterre wat dit verdoesel wat op foto's gesien kan word. Dit is 'n indrukwekkende astrofotografie-teiken met standaard kameralense en 'n opsporing.

Beste besigtigingstye: Februarie en # 8211 Augustus

3. Carina-newel (NGC 3372)

Die Carina-newel is een van die grootste diffuse newels aan die hemel, geskat tussen 6.500 en 10.000 ligjaar van die aarde af. Hierdie komplekse mengsel van gas, ook bekend as die Groot Nevel in Carina, bevat verskeie oop trosse en verskeie ander helder en helder sterre, soos die beroemde Eta Carinae-stelsel. Hierdie newel is ongeveer vier keer so groot as die helderheid van die meer bekende Orion-newel.

Beste besigtigingstye: Februarie en # 8211 Julie

4. Omega Centauri (NGC 5139)

Die grootste bekende bolvormige groep in ons Melkwegstelsel verskyn in die sterrebeeld Centaurus. Daar word beraam dat hierdie skouspelagtige suidelike hemelbril ongeveer 10 miljoen sterre bevat, terwyl die grootste bolvormige groep in die noordelike breedte, die Groot bolvormige groep in Hercules (M13), 300 000 sterre bevat.

Beste besigtigingstye: Maart en # 8211 Augustus

5. Groot en klein Magellaanse wolke (LMC en SMC)

Hierdie duo van onreëlmatige dwergstelsels is wonderlike en prominente kenmerke aan die suidelike hemelruim en word dikwels met die blote oog as aardwolke verkeerd beskou. Albei is lede van die Plaaslike Groep sterrestelsels, en dit word vermoedelik om ons eie Melkwegstelsel wentel.

Die ware afstand tussen hierdie twee sterrestelsels is 75 000 ligjare, terwyl dit slegs 21 ° van mekaar in die lug verskyn. Die LMC lê na raming 160 000 ligjare van die aarde af, en die SMC ongeveer 200 000 ligjare ver.

Die LMC bevat 'n gewilde suidelike juweel, bekend as die Tarantula-newel (30 Doradus). Terwyl 'n ander opvallende teiken naby die SMC gesien word, is 47 Tucanae, 'n groot bolvormige groep wat 16 700 ligjaar van die aarde af is en met die blote oog gesien kan word. Hierdie tros het 'n baie helder en digte kern en is die 2de helderste bolvormige tros in die naghemel na Omega Centauri.

Beste besigtigingstye: Oktober en # 8211 Maart


Baie verskillende kleure

Die kleur van die lig wat vrygestel word, hang af van die soort gasmolekules, hul elektriese toestand tydens die botsing en die tipe sonwinddeeltjies waarmee hulle bots. Suurstofatome straal geelgroen of rooi kleur uit, terwyl stikstofatome blou of persrooi kleur gee. 'N Mengsel van gasse in die aarde se atmosfeer skep veelkleurige auroras.

Omdat deeltjies van sonwinde voortdurend die aarde se atmosfeer binnedring en met gasatome in wisselwerking is, kan aurora-uitstallings staties sowel as dinamies wees - dit kan van vorm en kleure verander en in die lug pols.


Prettige nag wat pronk

Soms kom die feit dat ek baie tyd onder die sterre deur my teleskoop staar, in 'n gemaklike gesprek en ek kan nie onthou dat iemand belangstelling in die onderwerp getoon het nie. Hulle merk op hoe wonderlik dit sou wees om sterre en planete en die maan deur 'n teleskoop te sien, maar as daar 'n geleentheid is om by my aan te sluit en te kyk, neem min mense my die aanbod aan, en as hulle dit doen, is dit gewoonlik 'n paar sekondes kyk na 'n paar voorwerpe en 'n paar, "o, dit is interessante" opmerkings. Ek doen nie gereeld uitreike nie, en die meeste mense wat na my okulêr kom, is vriende of bure, so my steekproefgrootte is klein, maar ek het 'n algemene begrip dat dit tyd en moeite verg om 'n dieper belangstelling in waarneming te ontwikkel. .

Dit het die ervaring van gisteraand spesiaal gemaak. Ons het 'n paar studente wat by ons woon. Een uit België en 'n ander uit Japan. Hulle het my teleskoop gesien en ons het kortliks daaroor gepraat, maar dit was oor die algemeen bewolk die laaste paar weke en daar was geen goeie aand om hulle iets te wys nie. Gisteraand noem ek dat ek my omvang gaan instel en dat ek graag 'n paar dinge aan hulle sal wys as hulle belangstel. My verwagtinge was laag, maar hulle het opregte belangstelling getoon en ek het gedink dat hulle ten minste 'n uitsig oor die wasende maan sou geniet.

Om 'n langverhaal kort te maak, was die maan mooi en was hulle regtig beïndruk en wou hulle meer hê. Ek draai na die Pleiades om hulle te vang voordat hulle te laag word en verduidelik dat hulle na 'Subaru' kyk. Hulle het die groep met hul blote oog gevind en ook deur die teleskoop gekyk. Ons het na Betelgeuse getrek om die dramatiese verskil in kleur tussen die blou sterre van die Pleiades te sien. Hulle het dit geniet om van die verskillende soorte sterre, groottes en ouderdomme te hoor. Ek draai na die Orionnevel. Omdat ek geweet het dat die maan die helderheid van die newel sou wegspoel, het ek dit gebruik om te verduidelik dat hulle na 'n stervormige tros kyk wat eendag baie op die Pleiades sou lyk as al die stof opgebruik of weggewaai is. . Ek het ook van die geleentheid gebruik gemaak om die struktuur van Orion en sy gordel, swaard, ensovoorts aan te dui. Hulle het heen en weer beweeg tussen die verkyker, die teleskoop en die blote oog.

Ek het my na Ursa Major gewend. Hulle het die 'Great Bear' herken en ons het 'n paar minute aan die veelvoudige ster Mizar deurgebring wat hulle ook geniet het.

Op hierdie stadium was die Japannese student klaar, maar die Belg wou 'n bietjie meer hê. Ek wou hom 'n sterrestelsel wys, maar het geweet dat dit nie die ideale aand daarvoor was nie. Aangesien ek al in Ursa Major was, het ek gedink dat M81 / 82 miskien helder genoeg sou wees en dat dit vir hom indrukwekkend kon wees om twee sterrestelsels in dieselfde gesigsveld te wys. Dit het 'n paar minute geneem (ek vind alles handmatig), maar ek het hulle gebel en hy was so beïndruk dat hy sy foon uitgetrek het om sy vriendin te SMS. Dit het sy nagvisie natuurlik verwoes, maar my die geleentheid gegee om inligting op my foon op te tel oor die afstand na die sterrestelsels en foto's. Die feit dat die lig uit daardie sterrestelsels ook ongeveer 25 miljoen jaar was om ons te bereik, het 'n bietjie gedink (wat presies my bedoeling was!).

Al met al, 'n geleentheid om 'n aantal verskillende soorte voorwerpe te vertoon en 'n baie aangename ervaring vir ons al drie!


Het u foto's wat die maanverskil tussen suidelike en noordelike waarnemers toon? - Sterrekunde

Jeff's Driveway Astronomy Page

Komeet PanSTARRS - 21 Maart 2013

20 Februarie 2008 Maansverduistering

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Lunar-X / 1 Maart 2020

Selfoonkamera hou tot 18mm Kellner-okular van my 'Deck-Dob' (4,5-inch F / 8-reflektor)

1 Maan naby Jupiter (oggendhemel) om 13h UT. Mag. & # 87222.4.
Jupiter (Wikipedia)
2 Laaste kwartaalmaan om 7:25 UT.
8 Maan op apogee (verste van die aarde af) om 2 uur UT (afstand 406,228 km hoekgrootte 29,4 ').
8 Maan naby die Pleiades (18 van son, oggendhemel) om 21 uur UT.
The Pleiades (Wikipedia)
10 Nuwe maan om 10:53 UT. Aanvang van lunasie 1218.
10 Ringvormige sonsverduistering van 9:50 tot 11:34 UT. Grootste verduistering om 10:43 UT. Die pad van ringvormigheid strek oor Noord-Kanada, Groenland en Rusland. Gedeeltelike verduistering in N. Amerika, Europa en Asië.
Ringvormige sonsverduistering van 2021 10 Junie (GIF) (NASA)
Sonverduisterings: 2011 - 2030 (Eclipse)
NASA Solar Eclipse Page (NASA)
Totale sonsverduisterings: hoe algemeen kom dit voor in die sonnestelsel? (video) (ASSA / YouTube)
11 Kwik by minderwaardige voegwoord met die son om 1 uur UT. Mercurius gaan in die oggendhemel oor.
12 Venus 1.5 SSW van die maan (20 van son, aandhemel) om 8 uur UT. Mag. & # 87223.9.
Venus (Wikipedia)
13 Maan naby Castor om 2 uur UT (aandhemel).
13 Maan naby Pollux om 7h UT (aandhemel).
13 Maan naby Mars (38 van son, aandhemel) om 22 uur UT. Mag. 1.8.
Mars (Wikipedia)
14 Maan naby Byekorfgroep M44 (aandhemel) om 9h UT. Die Beehive is 'n pragtige gesig in 'n verkyker.
Byekorfgroep (Wikipedia)
M44: The Beehive Cluster (APOD)
16 Maan naby Regulus om 4h UT (aandhemel).
Regulus (Wikipedia)
18 Eerste kwartaal maan om 3:54 UT.
19 Venus 8.7 S van Castor (23 van Son, aandhemel) om 13h UT. Mag. & # 87223.9.
20 Maan naby Spica om 4h UT (aandhemel).
Spica (Wikipedia)
21 Junie-sonstilstand om 3:32 UT. Die tyd wanneer die son die punt bereik het die verste noord van die hemelse ewenaar, wat die begin van die somer in die Noordelike Halfrond en die winter in die Suidelike Halfrond aandui.
Junie-sonstilstand (Wikipedia)
Equinoxes en sonstilstande uit die ruimte
21 Venus 5.2 S van Pollux (23 van Son, aandhemel) om 22 uur UT. Mag. & # 87223.9.
23 Maan naby Antares om 7h UT (aandhemel).
Antares (Wikipedia)
23 Maan by perigee (naaste aan die aarde) om 9:52 UT (afstand 359 956 km hoekgrootte 33,2 ').
23 Mars 0,03 SE van die Beehive-groep M44 (aandhemel) om 23 uur UT. Mag. 1.8. Mars bied 'n pragtige gesig as dit deur M44 loop.
24 Volmaan om 18:39 UT.
27 Maan naby Saturnus (oggendhemel) om 12 uur UT. Mag. 0.4.
Saturnus (Wikipedia)
28 Maan naby Jupiter (oggendhemel) om 22 uur UT. Mag. & # 87222.6.
Jupiter (Wikipedia)

& gt & gt & gt Alle tye in Universele Tyd (UT). Amerikaanse sentrale standaardtyd = UT-6 uur. (DST = UT-5 uur,)

Die Zodiacal Light word veroorsaak deur sonlig wat weerkaats word deur stof in die sonnestelsel. Kies 'n helder, maanlose nag, ongeveer 1-2 uur na sononder, en soek 'n groot driehoekige gloed wat vanaf die horison (langs die ekliptika) strek. Die beste maande om die Zodiacal Light te besigtig, is wanneer die ekliptika byna vertikaal is: die Maart en April (aand) en Oktober-November (oggend) is vir die suidelike halfrond omgekeer.
Zodiacal Light (Wikipedia)
Astronomieprentjie van die dag (APOD)
Foto van die sterreteken (Weerlandskappe)

- 'n paar uitdagende voorwerpe, en 'n paar maklike voorwerpe vir gewone verkykers. . . GROOT ook vir klein omvang!

Groot Meteorbuie in 2021

Stort Stralend en rigting Oggend van maksimum Beste uurlikse tarief Ouer
Kwadrantid * Draco (NE) 4 Januarie 60-100 2003 EH1
Lyrid * Lyra (E) 22 April 10-20 Thatcher (1861 I)
Eta Waterdraer Waterman (E) 5 Mei 20-60 1P / Halley
Delta Aquariid * Waterman (S) 29 Julie 20 96P / Machholz
Perseid Perseus (NE) 12 Augustus 90 109P / Swift-Tuttle
Draconid Draco (N) 7 Oktober 10-100 21P / Giacobini-Zinner
Orionid * Orion (SE) 21 Oktober 10-20 1P / Halley
Suidelike Taurid Taurus (S) 5 November 10-20 2P / Encke
Leonid * Leo (E) 17 November 10-20 55P / Tempel-Tuttle
Tweeling * Tweeling (S) 14 Desember 100-120 3200 Phaethon
Ursid * Ursa Minor (N) 22 Desember 10 8P / Tuttle
* Maanlig sal in hierdie buie flouer meteore uitspoel.

Gewaagde stortname dui die beste voorspelde Meteorbuie aan!

Die meteorietbui hierbo is die maklikste om te sien en bied die meeste aktiwiteit. Let veral op die tyd en maanlig. Al hierdie storte word die beste gesien na middernag. Sommige is eers na middernag sigbaar. Buie wat 'n hoogtepunt bereik met die maan se ouderdom tussen 10 en 20 dae, word deur die maanlig beïnvloed en dit is moeilik om hierdie jaar waar te neem. Terwyl die tyd dat elke stort die beste gesien word, jaar na jaar baie dieselfde bly, verander die maanligtoestande aansienlik van die een jaar na die volgende.

Gebruik asseblief die vorm HIER van die American Meteor Society om enige meteoriete wat u sien, aan te meld. Instruksies oor die invul van die vorm kan HIER gevind word.


Inhoud

  • 'N Nuwemaan verskyn die hoogste op die somerstilstand en die laagste op die winterstilstand.
  • Die eerste kwartmaan verskyn die hoogste op die lente-ewening en die laagste op die herfs-ewening.
  • 'N Volmaan verskyn die hoogste op die wintersonstilstand en die laagste op die somersonstilstand.
  • 'N Laaste kwartmaan verskyn die hoogste op die herfs-ewening en die laagste op die lente-ewening.

Nie-Westerse kulture kan 'n ander aantal maanfases gebruik, byvoorbeeld, die tradisionele Hawaiiaanse kultuur het altesaam 30 fases (een per dag). [2]

Waks en kwynend Redigeer

Wanneer die Son en Maan aan dieselfde kant van die Aarde in lyn is, is die Maan 'nuut', en die kant van die Maan wat na die Aarde kyk, word nie deur die Son verlig nie. Soos die maan wasse (die hoeveelheid verligte oppervlak van die aarde af neem toe), die maanfases vorder deur nuwe maan, sekelmaan, eerste kwartmaan, maan en volmaan. Daar word dan van die Maan gesê kwyn as dit deur die maan, derde kwartmaan, sekelmaan en terug na nuwe maan gaan. Die bepalings ou maan en nuwe maan is nie uitruilbaar nie. Die 'ou maan' is 'n kwynende flentertjie (wat uiteindelik vir die blote oog onopspoorbaar word) tot op die oomblik dat dit in lyn is met die son en begin groei, en dan word dit weer nuut. [3] Halfmaan word dikwels gebruik om die mane van die eerste en derde kwartaal te bedoel, terwyl die term kwartaal verwys na die omvang van die maan se siklus rondom die aarde, nie sy vorm nie.

Wanneer 'n verligte halfrond vanuit 'n sekere hoek bekyk word, het die deel van die verligte area wat sigbaar is, 'n tweedimensionele vorm soos gedefinieër deur die kruising van 'n ellips en sirkel (waarin die hoofas van die ellips saamval met die sirkel se deursnee) . As die half-ellips konveks is ten opsigte van die halwe sirkel, dan sal die vorm gibbous wees (na buite uitbult), [4] terwyl die half-ellips konkaaf is ten opsigte van die halwe sirkel, dan sal die vorm wees 'n sekelmaan. Wanneer 'n sekelmaan voorkom, kan die verskynsel van aardskyn sigbaar wees, waar die nagkant van die maan die indirekte sonlig weerkaats wat van die aarde af weerkaats. [5]

Oriëntering volgens breedtegraad Redigeer

In die Noordelike Halfrond, as die linkerkant (oostelike) kant van die Maan donker is, word die helder gedeelte al hoe dikker en word die Maan beskryf as waks (skuif na volmaan). As die regterkant (westekant) van die maan donker is, word die helder gedeelte dunner en word die maan beskryf as besig om te kwyn (verby vol en skuif na nuwe maan). As ons aanneem dat die kyker in die Noordelike Halfrond is, is die regterkant van die Maan die deel wat altyd aan die groei is. (Dit wil sê, as die regterkant donker is, word die maan donkerder as die regterkant verlig word, word die maan helderder.)

In die Suidelike Halfrond word die maan waargeneem vanuit 'n omgekeerde perspektief, of 180 ° gedraai, na die noordelike en al die beelde in hierdie artikel, sodat die teenoorgestelde kante lyk of dit kwyn.

Nader aan die ewenaar sal die maanafsluiter soggens en saans horisontaal vertoon. Aangesien die beskrywings van die maanfases hierbo slegs van toepassing is op middel- of hoë breedtegrade, sal waarnemers vanaf die noordelike of suidelike breedtegraad na die trope beweeg, die maan teen die kloksgewys of kloksgewys sien draai ten opsigte van die beelde in hierdie artikel.

Die maanmaan kan opwaarts of afwaarts oopgaan, met die "horings" van die halfmaan wat onderskeidelik op of af wys. Wanneer die son bo die maan in die lug verskyn, gaan die sekelopwaarts na onder oop as die maan bokant die son is, en die sekelopwaarts oopmaak. Die sekelmaan is die duidelikste en helderste sigbaar as die son onder die horison is, wat impliseer dat die maan bo die son moet wees, en dat die sekelopwaarts moet oopgaan. Dit is dus die oriëntasie waarin die sekelmaan meestal vanuit die trope gesien word. Die waksende en kwynende sekelhare lyk baie dieselfde. Die wassende maan verskyn in die aand aan die westelike hemel en die oggend aan die afneem in die oostelike lug.

Earthshine Edit

Wanneer die maan vanaf die aarde gesien is, 'n dun sekel is, word die aarde vanaf die maan byna volledig deur die son verlig. Dikwels word die donker kant van die maan dof verlig deur indirekte sonlig wat van die aarde af weerkaats word, maar is dit helder genoeg om maklik vanaf die aarde sigbaar te wees. Hierdie verskynsel word aardskyn genoem en soms skilderagtig beskryf as 'die ou maan in die arms van die nuwe maan' of 'die nuwe maan in die arms van die ou maan'.

Om die fase van die maan 'n maand lank elke dag te fotografeer (begin saans na sononder, en herhaal ongeveer 24 uur en 50 minute later en eindig die oggend voor sonop) en om die reeks foto's op 'n kalender te rangskik, sal 'n saamgestelde beeld skep soos die voorbeeldkalender (8 Mei - 6 Junie 2005) aan die linkerkant. 20 Mei is leeg omdat 'n foto voor middernag op 19 Mei en die volgende na middernag op 21 Mei geneem sal word.

Net so sal dit voorkom asof sommige dae op 'n kalender wat maan- of maanondergang bevat, oorgeslaan word. As maanopkoms een nag voor middernag voorafgaan, volg die volgende maanopkoms die volgende nag om middernag (so ook met maanondergang). Die 'oorgeslaande dag' is slegs 'n kenmerk van die maan se oostelike beweging in verhouding tot die son, wat op die meeste breedtegrade die maan later elke dag laat opkom. Die maan volg elke maand 'n voorspelbare baan.

Elk van die vier tussentydse fases duur ongeveer sewe dae (gemiddeld 7,38 dae), maar dit wissel effens as gevolg van maan-apogee en perigeum.

Die aantal dae wat getel word vanaf die tyd van die nuwemaan, is die "ouderdom" van die Maan. Elke volledige siklus van fases word 'n 'lunation' genoem. [6]

Die geskatte ouderdom van die maan, en dus die benaderde fase, kan vir elke datum bereken word deur die aantal dae sedert 'n bekende nuwemaan (soos 1 Januarie 1900 of 11 Augustus 1999) te bereken en hierdie modulo 29.53059 dae te verminder ( die gemiddelde lengte van 'n sinodiese maand). [7] [d] Die verskil tussen twee datums kan bereken word deur die Juliaanse daggetal van die een van die ander af te trek, of daar is eenvoudiger formules wat (byvoorbeeld) die aantal dae sedert 31 Desember 1899 gee. hierdie berekening veronderstel 'n volkome sirkelvormige wentelbaan en maak geen voorsiening vir die tyd van die dag waarop die nuwe maan plaasgevind het nie en kan dus enkele ure verkeerd wees. (Dit word ook minder akkuraat, hoe groter die verskil tussen die vereiste datum en die verwysingsdatum). Dit is akkuraat genoeg om dit in 'n nuutse kloktoepassing met maanfase te gebruik, maar spesialisgebruik met inagneming van maan-apogee en perigee vereis 'n meer uitgebreide berekening.

Die aarde onderwerp 'n hoek van ongeveer twee grade as dit vanaf die maan gesien word. Dit beteken dat 'n waarnemer op Aarde wat die maan sien as dit naby die oostelike horison is, dit vanuit 'n hoek sien wat ongeveer 2 grade verskil van die siglyn van 'n waarnemer wat die maan op die westelike horison sien. Die maan beweeg ongeveer 12 grade om sy baan per dag, dus as hierdie waarnemers stilstaan, sal hulle die fases van die maan sien op tye wat ongeveer een sesde van 'n dag of vier uur verskil. Maar in werklikheid is die waarnemers op die oppervlak van die roterende aarde, so iemand wat die maan op die oostelike horison op 'n oomblik sien, sien dit ongeveer 12 uur later op die westelike horison. Dit voeg 'n oscillasie toe aan die skynbare vordering van die maanfases. Dit lyk asof hulle stadiger voorkom as die maan hoog in die lug is as wanneer dit onder die horison is. Dit lyk asof die maan rukkerig beweeg, en die fases doen dieselfde. Die amplitude van hierdie ossillasie is nooit meer as ongeveer vier uur nie, wat 'n klein fraksie van 'n maand is. Dit het geen duidelike uitwerking op die voorkoms van die maan nie. Dit beïnvloed egter akkurate berekeninge van die tye van maanfases.

Orbitale periode Redigeer

Dit kan verwarrend wees dat die wentelperiode van die maan 27,3 dae is, terwyl die fases een keer elke 29,5 dae 'n siklus voltooi. Dit is as gevolg van die aarde se draai om die son. Die maan wentel 13,4 keer per jaar oor die aarde, maar beweeg net 12,4 keer tussen die aarde en son.

Verduisterings Redigeer

Daar kan verwag word dat die skaduwee een keer per maand, wanneer die maan tussen die aarde en die son tydens 'n nuwe maan gaan, op die aarde sal val en 'n sonsverduistering sal veroorsaak, maar dit gebeur nie elke maand nie. Dit is ook nie waar dat die aarde se skaduwee tydens elke volmaan op die maan val en 'n maansverduistering veroorsaak nie. Sons- en maansverduisterings word nie waargeneem nie elke maand omdat die planeet van die maan se baan om die aarde met ongeveer 5 ° gekantel is ten opsigte van die vlak van die aarde se baan om die son (die vlak van die ekliptika). Wanneer nuwe en volle mane voorkom, lê die maan dus gewoonlik noord of suid van 'n direkte lyn deur die aarde en son. Alhoewel 'n verduistering slegs kan plaasvind as die Maan nuut (son) of vol (maan) is, moet dit ook baie naby die kruising van die Aarde se wentelvlak rondom die Son en die Maan se wentelvlak rondom die Aarde geplaas word (dit wil sê by een van sy nodusse). Dit gebeur ongeveer twee keer per jaar, en daar is dus tussen vier en sewe verduisterings in 'n kalenderjaar. Most of these eclipses are partial total eclipses of the Moon or Sun are less frequent.


When to see the best meteor showers

Lyrids [N/S N favored]

Active: April 14–30

Maximum: April 22, 1pm UTC = 11pm AEST (Qld) = 7am CST = 3am Hawaii time

The Lyrids are one of the meteor showers with the longest and most storied histories, with recorded observations spanning millenia. In the past, they were one of the year’s most active showers, with a history of producing spectacular meteor storms.

Nowadays, the Lyrids are more sedate, putting on a reliable show without matching the year’s stronger showers. They still throw up occasional surprises such as an outburst in excess of 90 meteors per hour in 1982.

This year’s peak Lyrid rates coincide with the first quarter Moon, which will set around midnight, local time, for most locations. The best time to observe will come in the early hours of the morning, after moonset.

For observers in the northern hemisphere, the Lyrid radiant will already be at a useful altitude by the time the Moon is low in the sky, so some brighter meteors might be visible despite the moonlight in the late evening (after around 10:30pm, local time).

Once the Moon sets the sky will darken and make the shower much easier to observe, yielding markedly higher rates.

For observers in the southern hemisphere, the Lyrid radiant reaches a useful altitude in the early hours of the morning, when the Moon will have set. If you’re a keen meteor observer, it could be worth setting your alarm early to get out and watch the show for a few hours before dawn.

The Boorong from north-western Victoria saw the Lyrids as Neilloan, the Mallee fowl, kicking up shooting stars while preparing her nest. Melbourne, 5am. Museums Victoria/Stellarium

Lyrid meteors are fast and often quite bright so can be rewarding to observe, despite the relatively low rates (one every five or ten minutes, or so). Remember, this shower always has the potential to throw up an unexpected surprise.

Eta Aquariids [S]

Active: April 19–May 28

Maximum: May 6, 3am UTC = 1pm AEST (Qld/NSW/ACT/Vic/Tas) = 11am AWST (WA)

The Eta Aquariids are an autumn treat for southern hemisphere observers. While not one of the big three, they stand clear as the best of the rest of the annual showers, yielding a fine display in the two or three hours before dawn.

The Eta Aquariids are fast meteors and are often bright, with smoky trains. They are fragments of the most famous comet, 1P/Halley, which has been laying down debris around its current orbit of the Sun for tens of thousands of years.

Earth passes through that debris twice a year, with the Eta Aquariids the best of the two meteor showers that result. The other is the Orionids, in October.

Where most meteor showers have a relatively short, sharp peak, the Eta Aquariids remain close to their best for a whole week, centred on the maximum. Good rates (ZHR > 30 per hour) should be visible before sunrise on each morning between May 3–10.

The Moon will be a waning crescent when the Eta Aquariids are at their best. Its glare should not interfere badly with the shower, washing out only the faintest members.

Observers who brave the pre-dawn hours to observe the Eta Aquariids will have the chance to lie beneath a spectacular sky. The Milky Way will be high overhead, with Jupiter, Saturn and the Moon high to the east and bright, fast meteors streaking across the sky from an origin near the eastern horizon.

The crescent Moon, the two biggest planets, a couple of bright stars and the Eta Aquariids all in the east before sunrise on May 6. Australia, around 4am local time. Museums Victoria/Stellarium

Perseids [N]

Active: July 17–August 24

Maximum: August 12, 7pm–10pm UTC = 8pm–11pm BST = August 13, 4am–7am JST

The Perseids are the meteoric highlight of the northern summer and the most observed shower of the year. December’s Geminids offer better rates but the timing of the Perseid peak makes them an ideal holiday treat.

The Perseids are debris shed behind by comet 109P/Swift-Tuttle, which is the largest known object (diameter around 26km) whose orbit currently intersects that of Earth.

Perseid meteors are fast, crashing into Earth at a speed of about 216,000km/h, and often bright. While the shower is active, at low levels, for more than a month, the best rates are typically visible for at the three nights centred on the peak.

For observers at European latitudes, the Perseid radiant rises by mid-evening, so the shower can be easily observed from 10pm local time, and remains high all through the night. The later in the night you look, the higher the radiant will be and the more meteors you’re likely to see.

Aurigids [N favoured]

Active: August 28–September 5

Maximum: Potential Outburst on August 31, peaking between 9:15pm–9:40pm UTC = 10:15pm–10:40pm BST = 11:15pm–11:40pm CEST = September 1, 1:15am–1:40am Gulf Standard Time = September 1, 5:15am–5:40am AWST (WA)

Where the other showers are reliable and relatively predictable, offering good rates every year, the Aurigids are an entirely different beast.

In most years, the shower is barely visible. Even at its peak, rates rarely exceed just a couple of meteors seen per hour. But occasionally the Aurigids bring a surprise with short and unexpected outbursts of 30-50 meteors an hour seen in 1935, 1986, 1994 and 2019.

The parent comet of the Aurigids, C/1911 N1 Kiess, moves on an orbit with a period far longer than the parent of any other shower on our list.

It is thought the orbit takes between 1,800 and 2,000 years to complete, although our knowledge of it is very limited as it was only observed for a short period of time.

In late August every year, Earth passes through debris shed by the comet at a previous passage thousands of years into the past. In most years, the dust we encounter is very sparse.

But occasionally we intersect a denser, narrow stream of debris, material laid down at the comet’s previous passage. That dust has not yet had time to disperse so is more densely packed and hence gives enhanced rates: a meteor outburst.

Several independent research teams studying the past behaviour of the shower have all come to the same conclusion. On August 31, 2021, the Earth will once again intersect that narrow band of debris and an outburst may occur, with predictions it will peak around 21:17 UTC or 21:35 UTC.

Such an outburst would be short-lived. The dense core of the debris stream is so narrow it will take the Earth just ten or 20 minutes to traverse. So you’ll have to be lucky to see it.

The forecast outburst this year is timed such that observers in Eastern Europe and Asia will be the fortunate ones, with the radiant above the horizon. The waning Moon will light the sky when the radiant is above the horizon, washing out the fainter meteors from the shower.

The Aurigids tend to be fast and are often quite bright. Previous outbursts of the shower have featured large numbers of bright meteors. It may just be worth getting up and heading outside at the time of the predicted outburst, just in case the Aurigids give us a show to remember.

Geminids [N/S]

Active: December 4–17

Maximum: December 14, 7am UTC = 6pm AEDT (NSW/ACT/Vic/Tas) = 3pm AWST (WA) = 2am EST

Parent: Asteroid 3200 Phaethon

The Geminid meteor shower is truly a case of saving the best until last. By far the best of the annual meteor showers, it graces our skies every December, yielding good numbers of spectacular, bright meteors.

The shower is so good it is always worth observing, even in 2021, when the Moon will be almost full.

Over the decades, the Geminids have gradually become stronger and stronger. They took the crown of the year’s best shower from the Perseids in the 1990s, and have continued to improve ever since.

For observers in the northern hemisphere, the Geminids are visible from relatively early in the evening, with their radiant rising shortly after sunset, and remaining above the horizon for all of the hours of darkness.

As the night progresses, the radiant gets very high in the sky and the shower can put on a truly spectacular show.

For those in the southern hemisphere, the situation is not quite as ideal. The further south you live, the later the radiant will rise, and so the later the show will begin.

When the radiant reaches its highest point in the sky (around 2am–3am local time), it sits closer to the horizon the further south you are, so the best meteor rates you observe will be reduced compared to those seen from more northerly locations.

Despite these apparent drawbacks, the Geminids are still by far the best meteor shower of the year for observers in Australia, and are well worth a look, even on the moonlit nights of 2021.

Peak Geminid rates last for around 24 hours, centred on the official peak time, before falling away relatively rapidly thereafter. This means that observers around the globe can enjoy the display.

The best rates come when the radiant is highest in the sky (around 2–3am) but it is well worth looking up at any time after the radiant has risen above the horizon.

So wherever you are on the planet, if skies are clear for the peak of the Geminids, it is well worth going outside and looking up, to revel in the beauty of the greatest of the annual meteor showers.

This article was originally published on The Conversation by Jonti Horner at the University of Southern Queensland and Tanya Hill at the University of Melbourne. Read the original article here.


The Lunar Landscape

The Moon, sometimes called Luna, is a wonderful sight and many amateur astronomers love to learn their way around it. However, many astronomers hate the Moon because, when it is full, its brightness is so overwhelming that it hides many dim stars, meteors, nebula, etc. Indeed, even astronomers who love to view the Moon often hate it when it's full because a Full Moon hides most of its more delicate features.

Of course, the Moon is a world of its own and it has its own geography (actually, a "lunagraphy"). Much has been learned about the Moon in the last few decades but there is still a lot to discover. Entire books have been written about the geology of the Moon and there is enough information that we could have an entire course, as big as this astronomy course, just about the Moon! But we won't. Instead I want to limit this lesson to a tour of the features on the Moon. I won't try teaching you the features on the far side of the Moon because chances are you wouldn't find it useful.

I like to think that the Moon is a rainbow of colors but all of them are gray. What I mean is that the variations in the Moon are subtle and can change due to the way that particular part of the Moon is illuminated.

Where do you find the best views?

The best views of the Moon occur along the terminator - a sharp line which divides the sunlit and dark parts of the Moon. The terminator represents that part of the Moon experiencing sunrise or sunset. (Think about that for a moment and convince yourself that makes sense.) Whenever you look at the Moon, especially with optical devices, pay particular attention to the area near the terminator. The angle of the sunlight brings out features that often disappear as the terminator moves on. That's because at sunrise or sunset objects project their greatest shadows. Craters and mountains have a real three-dimensional look when the terminator is near them. If you look at the same spot some days later, when it's in more direct sunlight, you will notice that the finer details are now gone and the brightness of the fully illuminated area causes it to have lost much of its beauty.

The most obvious features on the Moon are the "seas" called maria (singular "mare"). Of course, they aren't seas at all. They are relatively flat areas produced between 3.8 and 3.1 billion years ago by massive flows of lava. When the molten lava first erupted it behaved like water and, while still in a liquid state, it flooded the surrounding areas and filled in much of the low-lying land. Today, those maria produce the "man-in-the-Moon". These lava flows are made mostly of a rock called basalt . Basalt is what commonly remains of lava flows on Earth, too. Lunar basalts are made mostly of pyroxene (a silicate mineral rich in magnesium) and ilmenite (which itself contains lots of titanium - the strongest metal). Basalts are very dark so maria are obvious features on the Moon.

Maria cover about 16% of the Moon but they are not evenly distributed. The near side ("our side") is rich in maria while maria on the far side are small and scarce. That's because the Moon's center of mass is not at its geometric center. The Moon's center of mass is shifted about 2 kilometers in our direction.

So, the Moon's crust (outer layer) is thinner on the near side than on the far side. That means the magma (molten rock underground, before it erupts as lava) was more likely to make it to the surface and produce lava flows on the near side than on the far side.

Highlands make up the rest of the Moon's surface. These are very rugged and heavily cratered lands. Chances are these areas of the Moon got bombarded by meteors just as much as the maria areas but the maria lavas covered up the damage. Therefore, the highlands represent the oldest surface of the Moon. Most of the highlands formed between 4.0 and 3.8 billion years ago although some highland materials date as far back as 4.3 billion years. The intensive bombardment started about 4.6 billion years ago and that is considered the age of the Moon because it is supposed that is when the Moon first started to solidify. [Rocks this old are dated by the ratio of potassium to argon inside them. I don't want to go further into this - I've already included more geology here than I intended! You can learn all about rock dating methods elsewhere on the web.]

The highlands have been so battered by ancient impacts that most of the surface has been reduced to a rubble that geologists call breccia . Most of this breccia is composed of a mineral called plagioclase feldspar, which is rich in calcium and aluminum. There is also plenty of olivine (a silicate mineral containing lots of iron) and pyroxene (a silicate mineral rich in magnesium). Many highland rocks are enriched in certain elements that normally are not found in rocks on Earth. These rocks are called KREEPs because they contain lots of potassium (chemical abbreviation "K"), rare-earth elements (abbreviated "REE") and phosphorus (chemical abbreviation "P")

Why don't we mine those KREEPy breccias?

They're too far away! It takes a lot of energy to bring them back.

Highlands are sometimes called "terrae" which literally translates as "earth" so I don't like to use that confusing term. I think a better term might be "breccia land" or simply "rubble". Indeed, the impacting meteoroids and asteroids have ground a large portion of the Moon to dust! This dust, called regolith , covers most of the highlands and the maria like a thin blanket but may be up to 20 meters deep in some places.

The Moon has many mountains , especially in the highlands and between the maria. There is no erosion on the Moon so these mountains are very jagged and often very steep. Also, the low gravity of the Moon (one-sixth that of Earth) allows mountains to be very tall. Some mountain peaks reach elevations of 4 or 5 kilometers above the lunar surface! They are particularly striking when the terminator is nearby. Large mountain ranges are often at the borders of maria, presumably because the lava flows were not big enough to cover the mountains but were extensive enough to cover the foothills. Of course, where you find mountains you will find valleys and some of them cut nicely through the lunar mountain ranges. To see these valleys or details of the mountains you really must use a telescope.

Of course, the most "moonish" features of the Moon are its craters . These were caused when meteoroids or asteroids impacted onto the Moon. This bombardment still goes on today but not with the frequency it did billions of years ago. Most of these collisions hurled materials away from the point of impact in a radial pattern (like the spokes on a wheel). Some of this material is brightly colored and when it landed on the lunar surface it produced bright rays against the dark landscape that are still visible today. It will take about a billion years for these rays to fade. (They will eventually be obliterated by other impacts. But then, those new impact craters may produce rays of their own.) The best time to catch these Moon rays is during the Full Moon ( ) because then the Sun is positioned in such a way so as to make the rays shine.

Some of the bigger craters have a mountain peak or two in their centers. Some peaks are kilometers high! Such peaks were produced at the time of the impact. The material within the crater was immediately melted by the impact energy. The center of this pool of molten Moon was then caught up by the shock wave that rebounded off the crater's walls and hurled the material upwards where it solidified as a sharp column of rock. You can see this effect if you carefully watch drops (of anything) falling into a glass of water. These central peaks never rise as high as the crater walls.

Sometimes the inner walls of a crater will be too steep and loose. This can cause a "landslide" and the inner walls of the crater collapse. This might have happened several times producing a staircase pattern that we call terraced .

Some of the largest craters, which were probably formed long ago, when the Moon was still being bombarded by very big objects, have experienced lava flows within the crater. This produced walled plains which appear as large flat areas encircled by a low wall of an ancient, now partially buried, crater. If you look carefully you will see that many of the maria are defined by walled plains and mountain ranges.

Do you need a telescope to see these things?

Yes, you really need a telescope to see the details in craters. You certainly need magnification for you to see rills (also called rilles or clefts). Rills look like dried up riverbeds and can be either straight or irregular. The irregular rills were probably created by flowing lava behaving like water and moving like a stream. The straight rills are probably faults like those on Earth - formed when a part of the surface collapsed on one side of the rill, leaving a cliff face. They are fairly common on maria because the basalt plains of the maria are only a few meters thick (but some may be thicker). Maria, however, are very wide. The crust under them easily deforms causing the surface to crack and sink, producing a fault that looks like a straight rill.

A telescope would also allow you to see and understand the history of the Moon. Geologists, whether they study the Earth or other worlds, often behave as detectives in order to piece together an event that happened long ago. One common technique is to study the patterns produced as one geological process overlaid another.
For example, a crater with a floor of lava, a "walled plain", is a two-step process. The crater must have been there first and the lava filled in the floor of the crater at a LATER time.
A rill passing through a crater must have passed through the crater AFTER the crater was formed.
Overlapping craters provide a series of time points in which we can deduce that the most recent crater is the one with the complete rim. The oldest crater will be the one that is the most obliterated by the subsequent impacts from its overlapping neighbors.
By studying these details of crater overlap, lava flows and rills, geologist can reconstruct the sequence of events that produced the current features.

I haven't brought up these lunar features with the intention that you run out and get a telescope. Instead, I want you to be aware that they exist. The Moon is an entire world with a complicated landscape and geology. If, after this course, you become serious about astronomy and are particularly interested in the Moon, you can get a telescope and make your own observations.

Most of the processes I have described occurred billions of years ago when the Moon was still very young. We know this from samples returned from the Moon and our understanding of both geology and the likely history of our Solar System. The Moon is now "dead". It no longer has volcanic activity because it has cooled down and there isn't enough radioactive materials in the Moon to produce enough heat to create new volcanoes. Bombardment still occurs but not like in the good ol' days. [Fortunately. Otherwise we too would be getting bombarded and one big asteroid can ruin your day. ] However, it would be unfair to say that nothing happens on the Moon. There are occasional reports of localized "glows" and "brightenings" that are called Lunar Transient Phenomena ( LTP ). We suspect these are caused by the release of gas from below the Moon's surface or the impact of something against the Moon. Some amateur astronomers specialize in looking for and recording LTPs. Of course, these folks have first become experts on lunar features and geography.

Maybe one day I will too. Show me some of the best features of the Moon.

OK. Throughout this lesson I will be using a single photo of the Moon as our point of reference. That's because I want you to see "the big picture", but it's impossible for one photo to show all the features of the Moon and a photo that shows the entire Moon must, by necessity, be a Full Moon, or close to it.

The image I am using is actually a composite of several images, taken at various times during various phases, in order to show all the best of the Moon all at once. (All the Moon photos on this page are derived from LunaView 2000).

I will divide the Moon into four quadrants in order to make our lesson more useful. These quadrants are NOT the lunar "quarters" that the Moon passes through each month.

I am just using this image as a guide to our lesson. And remember - the various shades of gray can be different from one night to the next. I have pictured the Moon as it would look through a pair of binoculars (or real good eyes). Through a telescope the picture would be mirrored (left and right) and, depending upon the scope, the Moon may appear inverted (upside-down).

As we go though this lesson keep in mind that subtle differences in brightness can make a world of difference and the views I show you may not be what you see. So let's get started!

The northeast quadrant is dominated by three large maria.

Mare Serenitatis (Sea of Serenity) is the more northerly one approaching the centerline of the Moon. Mare Crisium (Sea of Crises) is at the extreme east side. Mare Tranquillitatis (Sea of Tranquillity) is bordered by Mare Serenitatis to the northwest and Mare Fecunditatis (Sea of Fertility) on the southeast which is mostly in the Moon's Southern Hemisphere. Mare Vaporum (Sea of Vapors) is a small dark mare southwest of Mare Tranquillitatis. Another long, thin mare, Mare Frigoris (Sea of Cold), runs north of Tranquillitatis and across to the Western Hemisphere.

On the southwest side of Mare Serenitatis lie the Haemus Mountains which rise to over 2.4 kilometers. Along the southern border of Mare Frigoris is one of the most beautiful mountain ranges on the Moon, the Alps! With a telescope you can find the Alpine Valley on the western border of this northeast quadrant. It cuts a full 130 kilometers through the Alps and a good telescope reveals a delicate rill along its floor as well as smaller valleys. Just to the south of the Alpine Valley is Mount Blanc, reaching a height of 3.5 kilometers.

There are plenty of craters to choose from but most require a telescope in order to be thoroughly enjoyed.

Crater Julius Caesar is irregularly shaped (not circular) and is just to the west of Mare Tranquillitatis. Its very dark floor causes it to stand out. On the floor of Mare Tranquillitatis, southeast of Julius and about half its size, is a nice (circular) crater called Arago. A good telescope shows "domes", elevated land, nearby. In the opposite direction, northwest of Julius, on the edge of Mare Vaporum is Manilius with walls made of a very reflective material that causes this crater to really stand out during a Full Moon. Between Mare Tranquillitatis and Mare Serenitatis is the crater Plinius. Between Mare Crisium and Mare Tranquillitatis is Proclus. It is the center of a nonsymmetric ray system and is a brilliant crater. Aristoteles is a large crater (100 kilometer in diameter with walls extending more than 3 kilometers above the floor) on the south edge of Mare Frigoris. Immediately south of Aristoteles lies the crater Eudoxus. There are several other large craters around Mare Frigoris including Endymion and Atlas along the west side of this mare and crater Bond on the north, opposite the Alpine Valley.

The northwest quadrant contains the gigantic Mare Imbrium (Sea of Showers) which takes up most of the north section, up to the Alps. The west end of this quadrant is covered by Oceanus Procellarum (Ocean of Storms). Just to the south of Mare Imbrium is the tiny mare called Sinus Aestuum (Bay of Heats), while on the other side of Mare Imbrium is Sinus Roris (Bay of Dews).

Most of the southeast side of Mare Imbrium is defined by the Apennines Mountains, with the Carpathians Mountains making up the rest of the south side. The northeast of Mare Imbrium is defined by the Alps and most of the north of the mare is bordered by the Plato Uplands.

Copernicus is the dominant crater in this quadrant. It's just south of the Carpathians. This crater is nearly 100 kilometers in diameter and a telescope shows its walls are terraced and, instead of a central peak, it has a complex mountain group of its own! During a Full Moon Copernicus' rays are the dominant feature in the Northern Hemisphere.

At the far western end of the Apennines is Eratosthenes, about half the size of Copernicus, with a high central peak and tall walls (seen with a good telescope).

On the other side of Copernicus is Kepler, a small (35 kilometer diameter) crater with a very bright ray system of its own. Plato makes a significant dent (about 100 kilometers in diameter) into the eastern side of the Plato Uplands. It has a large walled plain of dark gray that makes it obvious, even during a Full Moon. Archimedes is slightly smaller than, and south of, Plato in Mare Imbrium. Its walled plains are obvious with a telescope. Just to the northeast of Archimedes (and also visible in our first quadrant images) are two smaller but distinct craters, Aristillus and Autolycus. Pythagoras crater is north of the Plato Uplands and it is so far north that it looks like an ellipse because the angle is so steep. But that angle also tends to bring out its best features (including a central peak, if you have a telescope). Aristarchus is a small (37 kilometer diameter) crater in Oceanus Procellarum with nice walls and central peak made of a highly reflective material that makes this crater the brightest crater on the Moon. (That doesn't count rays. Many other craters have brighter rays.)

Sometimes the Earthshine (sunlight reflected off the Earth) can slightly illuminate Aristarchus while it is still in shadow causing some folks to think they have discovered an active volcano on the Moon!

The southwest has more highlands than mare but some very nice maria are still found here. The largest mare here is Mare Nubium (Sea of Clouds) which lies smack in the center of this quadrant. Near its eastern side, and visible in a good telescope, runs the "straight wall" which is actually a fault line - the western side of the mare has fallen about 300 meters and the shadow it produces gives the illusion of a straight wall. West of Nubium is Mare Humorum (Sea of Humors). Oceanus Procellarum spills across the equator and into this quadrant. Much of the area is full of mountains, especially along the western rim. The Riphaean range borders the western side of Mare Nubium.

The southern hemisphere is so dominated by highlands that it is difficult to pick out specific craters, but some just have to be mentioned. Tycho is about 80 kilometers wide but it is the dominant crater in this area because during a Full Moon its rays seem to spread into all four quadrants!

South of Tycho and close to the southern edge is the gigantic (230 kilometer wide) crater called Clavius. Its walls are over 4 kilometers tall so, when the terminator is near, this crater can be seen with the naked eye. Walter and Ptolemaeus are dark floored, walled plains craters at each end of a chain of craters that form a prominent group to the east of Nubium. Probably the darkest looking crater in this quadrant is Grimaldi at the far west edge near the Lunar Equator.

The southeast quadrant is also made up mostly of highlands.

Mare Foecunditatis (Sea of Fertility), which starts in the north east quadrant, continues down the south east side of the Moon. To the west are the Pyrenees Mountains and west of them lies Mare Nectaris (Sea of Nectar). On the extreme southeast edge is Mare Australe (Sea of the South).

To the west of Mare Nectaris are three obvious craters. Theophilus is very deep with peaks rising 4.4 kilometers. It overlaps Cyrillus to its south, and farther south is Catharina. Piccolomi has very high walls which produce a striking relief when the terminus is near. This crater marks the beginning (or the end) of the Altai Scarp - not labeled in the photo but it's obvious running north towards Catharina. To the east of Mare Foecunditatis is the crater Langrenus which has walls about a kilometer high and two peaks near its center. During a Full Moon this crater is nothing more than a bright smear on the Moon.

What about all those other things?

There are many (MANY) features on the Moon that you could spend years learning all about, but all I am trying to do in this lesson is to introduce you to some of the Moon's most obvious features. With the naked eye you will be able to see only the larger maria and a few of the most brilliant craters. I've thrown in a few other features just to remind you that the Moon has plenty to offer someone with binoculars or a telescope.

Get outside and have a look at the Moon as it goes through its phases and as its terminator brings the different features into view. You don't need magnification but if you can borrow some binoculars you will see wonderful sites.

See you next month.
Wishing you "Clear Skies".
Jamie (Dr Love)


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