why is earth the only planet with oxygen

Free molecular oxygen is a very reactive chemical. It isn't typically found in large amounts unless it is continuously produced. On Earth, life is one major process that is producing significant levels of free oxygen. That is also why it is looked for on other planets as an attempt to find other life.

how did they find evidence on mars that there used to be running water

also, near the poles, underground, there is evidence of liquid water flowing underneath the surface, from satellite imagery showing drifts of the martian soil.

how many stars are in the milky way

We don't know the exact number, but it's estimated there are between 100-400 billion stars in the Milky Way galaxy.

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Big History Project

Course: Big History Project > Unit 4

Lesson 1: Earth & the Formation of Our Solar System | 4.0

ACTIVITY: Threshold Card —Threshold 4 Earth & the Solar System

Google Classroom

Each threshold follows a consistent pattern of creating greater complexity in the Universe. Download a PDF of Threshold 4 Earth & the Solar System.

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Elkia
Posted 7 years ago. Direct link to Elkia's post “Dose Jupiter have a core?”
Dose Jupiter have a core?
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- Lily
  Posted a year ago. Direct link to Lily's post “yes. Jupiter dose have a ...”
  yes. Jupiter dose have a core
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  (2 votes)
LeviP
Posted 4 years ago. Direct link to LeviP's post “why is earth the only pla...”
why is earth the only planet with oxygen
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(1 vote)
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- Davin V Jones
  Posted 4 years ago. Direct link to Davin V Jones's post “Free molecular oxygen is ...”
  Free molecular oxygen is a very reactive chemical. It isn't typically found in large amounts unless it is continuously produced. On Earth, life is one major process that is producing significant levels of free oxygen. That is also why it is looked for on other planets as an attempt to find other life.
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  (3 votes)
honyierou
Posted 8 years ago. Direct link to honyierou's post “do gas planets have crust...”
do gas planets have crust, mantle, core or just hydrogen and helium?
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(2 votes)
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- TheGamingDev
  Posted 8 years ago. Direct link to TheGamingDev's post “Most likely just gas, but...”
  Most likely just gas, but nobody knows for absolute sure
  Comment on TheGamingDev's post “Most likely just gas, but...”
  (1 vote)
Yellow Top White Knot
Posted 7 years ago. Direct link to Yellow Top White Knot's post “99% of material in a gas ...”
99% of material in a gas cloud goes into making a star and 0.1% into planets.

Is this because 99% of the material in a gas cloud is hydrogen and helium, which gravity draws into a star?
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(1 vote)
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sherly
Posted 2 years ago. Direct link to sherly's post “How did they figure out t...”
How did they figure out the pluto couldnt be seen And why?
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- Davin V Jones
  Posted 2 years ago. Direct link to Davin V Jones's post “Pluto can be seen with a ...”
  Pluto can be seen with a powerful enough telescope.
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  (1 vote)
chaubey.vikash
Posted a year ago. Direct link to chaubey.vikash's post “is a onther earth going ...”
is a onther earth going to form
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(1 vote)
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- David Alexander
  Posted a year ago. Direct link to David Alexander's post “In this living, expanding...”
  In this living, expanding universe, new planets are always in the process of forming somewhere or other. Whether any of them are habitable is another matter altogether.
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  (1 vote)
jana andrade
Posted 8 years ago. Direct link to jana andrade's post “how did they find evidenc...”
how did they find evidence on mars that there used to be running water
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(1 vote)
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- πTom_Pallister π
  Posted 8 years ago. Direct link to πTom_Pallister π's post “also, near the poles, und...”
  also, near the poles, underground, there is evidence of liquid water flowing underneath the surface, from satellite imagery showing drifts of the martian soil.
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  (2 votes)
Amrit Kaw
Posted 7 years ago. Direct link to Amrit Kaw's post “how many stars are in the...”
how many stars are in the milky way
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(0 votes)
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- Adeeba A.
  Posted 7 years ago. Direct link to Adeeba A.'s post “We don't know the exact n...”
  We don't know the exact number, but it's estimated there are between 100-400 billion stars in the Milky Way galaxy.
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  (2 votes)
꧁༒ÄĐ𝕀ƬɎÅ༒꧂
Posted 3 months ago. Direct link to ꧁༒ÄĐ𝕀ƬɎÅ༒꧂'s post “nah yall alreyd at collag...”
nah yall alreyd at collage nah bruh
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Hashir Safdar
Posted 8 years ago. Direct link to Hashir Safdar's post “How come Earth has so muc...”
How come Earth has so much more liquid water than any other planet?
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- Alfred
  Posted 8 years ago. Direct link to Alfred's post “Goldilocks condition: Ea...”
  Goldilocks condition: Earth is not too hot or too cold, not too big or too little, not too near the Sun or too far away, but just right for life to flourish.
  it is also theorized that Earth was hit by a large comet of ice.
  David's explanations of how the planets are formed is making my understanding of the Big History clearer.
  Comment on Alfred's post “Goldilocks condition: Ea...”
  (1 vote)