Mars used to be more like Earth.
Yes. Earth is about 6.5 times larger than Mars and has more mass.
Mars, the asteroid belt is in between Mars and Jupiter.
At opposition (Mars is opposite to the Sun), Mars can be between about 55 and 100 million kilometers - depending on where Earth and Mars meet (the orbit of Mars is quite a bit more excentric than Earth's orbit).
Earth is more massive than Mars and therefore has greater gravity.
Yes. Mars has two: Phobos and Deimos; Earth has only one.
There are no people on Mars.
Really small. 3.68x10^37% in scientific notation.
The Earth is more dense than Mars Mars mean density 3.9335 g/cm³ Earth mean density 5.515 g/cm3
Never. Mars and earth both orbit the sun. Since Mars has a more distant orbit, a year on Mars is almost the equivalent of two years on earth.
Mars only has about 28% the surface area of the Earth. What's interesting is that number matches the land area of Earth, so the total surface of Mars is roughly the same as the dry land surface of Earth.
None, because only half an Earth can fit inside of Mars.