Mercury
Uranus
Diameterkm
4,879
50,724
Mass (Earth = 1)x
0.06
14.54
Surface Gravitym/s²
3.70
8.87
Mean Temperature°C
+167
-220
Distance from SunAU
0.39
19.19
Orbital Perioddays
87.97
30,589
Day Lengthhours
4222.60
17.24
Known Moons
0
28
Axial Tilt°
0.03
97.77
Orbital Velocitykm/s
47.36
6.80
Quick Facts
Mercury
- -Mercury's day-night cycle lasts 176 Earth days -- longer than its year of 88 Earth days.
- -A person weighing 68 kg on Earth would weigh only 25.7 kg on Mercury.
- -Mercury has ice in permanently shadowed craters near its poles despite surface temperatures reaching 430°C.
- -Mercury is shrinking -- its circumference has decreased by about 14 km as its core slowly cools and contracts.
Uranus
- -Uranus rotates on its side with an axial tilt of 97.77°, likely caused by a massive ancient collision.
- -Uranus was the first planet discovered with a telescope, found by William Herschel in 1781.
- -All 28 of Uranus's moons are named after characters from Shakespeare and Alexander Pope.
- -Uranus's blue-green color comes from methane in its atmosphere absorbing red light.