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Orbit Bumi, Bulan dan
Gerhana
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Orbit Bumi dan BulanElips
Sun
Bumi
Moon
(Eksentrisitas diperbesar)
Perihelion = posisi
terdekat Bumi keMatahari
Aphelion
Perigee
Apogee = ?
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Fenomena
Fenomena apa saja yang dapat
teramati terkait orbit bumi dan
bulan?
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Fase-ase Bulan
Apa yang menyebabkan penampakan
bulan berubah-ubah?
!ambarkan
kenampakan
bulan tiap ase
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"e# MoonFirst $uarter Full Moon
Evening Sky
On morning t#ilight
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Full Moon %hird $uarter "e# Moon
Morning Sky
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Bulan mengorbit bumi dalam periode sideris
&'()& hari
&'()& days
EarthMoon
Arah tetap di ruang
angkasa
Periode *ideris
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periode sinodisbulan +untuk
men,apai posisi yang
sama relati thd
matahari adl &.(/) hr
+0 1 month(
Arah tetap di ruang
angkasa
Earth
Moon
Bumi mengorbit matahari
arah ke matahari berubah
&.(/) days
Periode *inodis
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Orbit Bumi dan Bulan
http://1-eclipses.mp4/http://1-eclipses.mp4/7/23/2019 Smt6 Astronomi 2-Gerhana
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!ambarkan skema gerhana bulan2
!ambarkan skema gerhana
matahari2
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Berdasarkan skema tsb3 menurut
anda berapa kali dalam setahun4
5 gerhana bulan
5 !erhana matahari
dapat terjadi?
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Mengapa gerhana tidak terjadi setiap
bulan?
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!erhana BulanBayangan
Bumi ada &41(Bayangan
parsial
penumbra
&(Bayanganpenuh
6mbra
7ika Bulan mele#ati umbra bumi gerhana bulan
7ika seluruh permukaan bulan memasuki 6mbra gerhana
bulan total
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!erhana Bulan %otal +1
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!erhana Bulan %otal +&!erhana bulan
total dapatberlangsung
hingga 1 jam 89
menit
*elama gerhanatotal3 bulan tampak
redup3 ber,ahaya
merah3
memantulkan
,ahaya matahari
yang dihamburkan
atmoser bumi
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!erhana Bulan4 &99&-&91&
Umumnya ,
1 atau 2
gerhana
bulan tiap
tahun
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!erhana Matahari
:i langit3 Matahari tampak hampir sebesar Bulan +diameter
sudut hampir sama 0 9(/9
;etika bulan le#at di depan matahari3 bulan dapat
menutupi matahari sepenuhnyagerhana matahari total
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!erhana Matahari4 &99&-&91&
Pendekatan1 gerhana matahari total
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!erhana Matahari %otal
Prominen,es
hromosphere and orona
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Atmoser Matahari %erlihat
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Eek in,in Berlian
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!erhana Matahari in,in
6kuran sudut
bulan dan
matahariber>ariasi3
tergantung
jarak dari
bumi
;etika Bumi di dekat perihelion3dan bulan di dekat apogee3 terlihat
gerhana matahari ,in,in(
Perigee Apogee Perihelion Aphelion
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!erhana Matahari in,in +&
ampir total3 gerhana ,in,in )9 Mei 1.@8
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*yarat terjadinya !erhana +1
!erhana matahari hanya
dapat terjadi jika bulan
mele#ati nodal saat sekitar
bulan baru
Orbit Bulan miring terhadap ekliptika sebesar 0 /9(
!erhana bulan hanya dapat
terjadi jika bulan mele#ati
nodal saat mendekati
purnama
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*yarat terjadinya !erhana +&
*iklus *aros:1@ tahun3 11 hari3 @ jam
!erhana terjadi dalam pola siklis
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%he *aros y,le
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%he %idesaused by the
dieren,e o the Moons
gra>itational attra,tion
on the #ater on Earth
& tidal maima
E,ess gra>itypulls#ater to#ards the
moon on the near sideFor,es are
balan,ed at the
,enter o the Earth
1&-hour ,y,le
E,ess ,entriugal
or,e pushes #ater
a#ay rom the moon
on the ar side
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*pring and "eap %ides
%he *un is also
produ,ing tidalee,ts3 about
hal as strong as
the Moon(
"ear Full and"e# Moon3
those t#o ee,ts
add up to ,ause
spring tides.
"ear irst andthird Cuarter3 the
t#o ee,ts #ork
at a right angle3
,ausing neap
tides(
*pring tides
"eap tides
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%he %idally-Do,ked Orbit o the Moon
%he Earth alsoeerts tidal or,eson the moons ro,kyinterior(
t is rotating #iththe same periodaround its ais as itis orbiting Earth+tidally lo,ked(
e al#ays seethe same side o themoon a,ing Earth(
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A,,eleration o the Moons Orbital
Motion
Earths tidal bulges areslightly tilted in the dire,tion
o Earths rotation(
!ra>itational or,epulls the moon slightly
or#ard along its orbit(
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