Mars atmosphere is much thinner than that surrounding the earth. It is composed mainly carbon dioxide with small amounts of nitrogen, argon, oxygen, carbon monoxide, neon, krypton and xenon. There are also tiny traces of water vapour, probably from the evaporation of the polar caps.
Mars has two small moons that travel around it. The closest one, Phobos, is also the largest of the two. It has a diameter of about fourteen miles at the equator and about eleven miles from pole to pole. It makes its revolution around Mars in about seven and a half hours. The smaller satellite, Deimos, has a diameter of about six miles and makes its journey around Mars in thirty hours. Asaph Hall, an American astronomer, discovered both the satellites in 1877.
Maximum temperature of mars is -5 degrease Celsius Minimum temperature of mars is -120 degrease Celsius
Mars is about four-fifths as dense as the earth but its mass in only about one-tenth that of the earth. Thus, its force of gravity is only about three-eighths that of the earth. A 100 pound object on earth would weigh about 38 pounds on Mars.
Mars is a terrestrial planet. It has a hard rocky surface that you could walk on. Mar’s surface is dry and is much covered with reddish dust and rocks. Mars has to permanent polar ice caps.
The surface gravity of mars is only about 39% of the surface gravity on earth. If you weigh 100 pounds on earth then you would only weigh 38 pounds on mars.
As said before Uranus atmosphere is about 83% hydrogen, 15% helium and 2% methane. There are also traces of water and ammonia. The planets atmospheric details are very difficult to see in visible light. The methane gas above the cloud layers gives it a blue-green colour.
The Planet Uranus has many moons. Five of largest are Miranda, Titania, Oberon, Umbriel, Ariel. The largest moon is Titania with a radius of only 788.9 km (less than half that of our Moon).
Uranus’s temperature averages to -210 degrease Celsius.
Uranus is a Gas Giant with no solid surface. More than 80 percent of the mass of Uranus is contained in an extended liquid core consisting primarily of icy materials (water, methane and ammonia) with higher-density material at depth.