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19 votes
Accepted

How could Mars' atmosphere be shed by solar winds, when Venus has a thick atmosphere despite no magnetic field?

I am not certain that the main cause of Mars losing most of its atmosphere was the solar winds. Long before the solar wind was discovered scientists calculated other factors which affect how long a ...
M. A. Golding's user avatar
15 votes

Can earth grazers skip on the atmosphere more than once?

I believe the answer is yes, when the asteroid after the initial pass through the earth's atmosphere no longer has escape velocity relative to the earth, but enters an elliptical orbit around the ...
antlersoft's user avatar
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14 votes

How could Mars' atmosphere be shed by solar winds, when Venus has a thick atmosphere despite no magnetic field?

One of the main loss mechanisms of atmospheres escape is thermal escape (Jeans escape) into space. The average thermal velocity at a given temperature $T$ for a molecule of mass $m$ is $$ v_{th} = \...
planetmaker's user avatar
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12 votes

Can earth grazers skip on the atmosphere more than once?

If by "more than once" you mean "more than once in a single visit", then that would seem impossible. After the first skip, the object is moving away from the earth. Either it has ...
BowlOfRed's user avatar
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8 votes
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Can a habitable planet be smaller than 0.58 Earth radii?

Short Answer: In part Two of the long answer below, it is stated that a planetary mass object needs to have a mass of at least 0.1, 0.12, 0.23, or 0.25 Earth mass to be habitable. Worlds with those ...
M. A. Golding's user avatar
8 votes

Can earth grazers skip on the atmosphere more than once?

I will not commit to a "yes" or "no" answer, but instead refer to examples of artificial objects that do go at least down-up-down. From Space Exploration SE: Did the Apollo ...
uhoh's user avatar
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5 votes
Accepted

...but where did Mars' atmosphere actually GO?

Assuming most of the escaping Martian atmosphere is entrained in the solar wind, it will flow outward until it reaches the termination shock, and then slow down in the heliosheath until it reaches the ...
Peter Erwin's user avatar
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5 votes

Role of aerobraking in cometary orbits?

About 0%. If they experience drag by the Sun's atmosphere, they desintegrate due to tidal stress (internal strength of comets is ~Pa < kPa, e.g. Heinisch et al (2019)). What does have an influence ...
planetmaker's user avatar
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4 votes
Accepted

Why does Titan have an atmosphere while similar moons such as the Galilean moons don't?

As in real estate, so in astronomy: Location, Location, Location Where an object forms in a system will significantly impact its makeup. For example, during the stage of planet(esimal) formation, due ...
zibadawa timmy's user avatar
4 votes
Accepted

Does Jupiter lose some atmosphere at all?

The phrase you hear is correct! Atmosphere will always be lost, no matter if it is a star or planet. Stars lose their mass via solar wind. Planets lose theirs via the three types of atmospheric loss ...
Max0815's user avatar
  • 1,862
3 votes

...but where did Mars' atmosphere actually GO?

There are three possible fates for small particles: They fall into the Sun. They escape the solar system. They fall into a planet. Small particles larger than 1 micron across tend to fall into the ...
David Hammen's user avatar
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2 votes

What stops terrestrial planets from becoming watery gas giants with water vapour atmospheres?

The terrestrial planets formed in their final configurations over the course of a hundred million years or so. The collision that formed the Moon probably occurred about 30-50 million years after the ...
ProfRob's user avatar
  • 155k
2 votes

Are planets far from their parent star more likely or less likely to have an atmosphere?

Not necessarily. There are lot of factors affecting the existence of a planet's atmosphere, the most predominant are: 1. Composition of the atmosphere. 2.Composition of the planet itself. 3. Star 4. ...
Kavin Ishwaran's user avatar
1 vote

Are planets far from their parent star more likely or less likely to have an atmosphere?

The question as asked cannot be answered easily; there too many parameters which determine the thickness of a planet's atmosphere. The main factors are the surface temperature and the planetary mass (...
planetmaker's user avatar
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