Questions tagged [phobos]

Questions about Phobos, the larger of Mars's two moons.

Filter by
Sorted by
Tagged with
1
vote
1answer
43 views

How did the orbits of Phobos and Deimos circularize?

The satellites of Mars might be captured asteroids. But Phobos has an eccentricity of $0.015$, and Deimos of $3\times10^{-4}$. If they were captured, they likely were captured with rather eccentric ...
4
votes
0answers
29 views

Has the inclination of the orbital plane of Phobos and Deimos followed that of Mars' axial tilt?

Phobos and Deimos are very close to Mars' equatorial plane (the inclination of their orbits is roughly 1°). The axial tilt of Mars has changed a lot over time, and might have had a inclination of over ...
11
votes
2answers
2k views

How many satellites orbit their planet faster than the planet rotates?

Phobos is so close to Mars that it orbits Mars much faster than Mars rotates. This means that it rises in the west and sets in the east, even though its orbit is prograde. Are there any other known ...
4
votes
1answer
78 views

Eclipses on Mars

This amazing video shows an annular eclipse of the Sun by Phobos as seen from Curiousity. This one shows an eclipse by Deimos. My question is do these things ever both happen at once? Do you ever get ...
4
votes
1answer
344 views

Mars night sky — Phobos and Deimos?

I'm having a debate about how bright Martian nights would be, in terms of both the sky itself and ground illumination. This answer seems to indicate that the stars would be only dimly visible, and ...
3
votes
1answer
765 views

How do we know that a natural satellite cannot be a hollow object?

In their 1966 book, Intelligent Life in the Universe, Carl Sagan and Iosif Shklovsky state that "a natural satellite cannot be a hollow object." How do we know this is absolutely true?
0
votes
1answer
208 views

When Phobos collides with mars (or breaks up), will it have any noticeable effects on Earth?

When Phobos meets its predicted doom in a few 10s of millions of years, whether it breaks up or collides with the surface of Mars, will this change have any noticeable effects (permanent or temporary) ...
5
votes
1answer
273 views

Formation and capture of Mars' moons, Phobos and Deimos

Mars's moons have the appearance of captured asteroids. How could this capture have taken place. An asteroid in solar orbit would need to loose some momentum to be captured. The gas Giants can ...
8
votes
2answers
450 views

How does gradual crossing over of the Roche limit transform a planet or moon?

Some cartoon simulations (an example) of an object (assume here a large moon with Earth-like density) which crosses the Roche limit of a much more massive giant planet, illustrate a circle suddenly ...