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Mars What would happen if you threw a pebble from Phobos or Deimos? The pebble will come back four hours later (15 hours on Deimos) and hit something on the moon with the same speed it was thrown at. What happens is the pebble temporarily is shot out of the gravity well of the Moon, but stays within Mars gravity well. The pebble forms a slightly elliptical orbit around Mars that intersects orbit of the moon halfway around Mars. Most friendly to life, other than the Earth. It is likely the easiest to terraform -- to make into our next living world. Longest synodic period - 779.94 days. We must wait more than two years to see Mars at its best. Consequentially, Mars also has the greatest range of angular sizes and brightnesses of any planet. Mars can look smaller than Uranus when Mars is at its worst (3 arc seconds vs 3.5 arc seconds), and can look larger than Saturn (excluding the rings) at its best (25 arc seconds vs 19 arc seconds). Mars can also range from +1.6 magnitude to -3.0 magnitude. Greatest topographic range of any planet -- 36 kilometers (Earth's topographic range is 20 km). It has mountains and valley that would put Earth's to shame. Its largest mountain, Olympus Mons, is 2.7 times larger than Mount Everest. Olympus Mons is 24 km high, wow. That means that somewhere in Mars there is a valley or crater 8 km deep as well. [Note: this record is now in doubt, information on the new record will come soon.] Phobos is the closest satellite to any planet -- at 9380 km. It is so close that this 26 by 18 km diameter moon shows a disc of 7 arc minutes, a third the angular diameter of our Moon as seen from Earth. The limiting latitude of Phobos is 69 degrees, and Deimos is 82 degrees. North or south of these latitudes these moons can not be seen. Today's weather forecast for Mars: Mars can actually get warm. In deep valleys during a perihelion (closest point to the Sun) summer at the right spot, the temperature may get up to a comfy 20 C. Forward to Jupiter |