Mercury
Venus
Diameterkm
4,879
12,104
Mass (Earth = 1)x
0.06
0.81
Surface Gravitym/s²
3.70
8.87
Mean Temperature°C
+167
+462
Distance from SunAU
0.39
0.72
Orbital Perioddays
87.97
224.7
Day Lengthhours
4222.60
2802.00
Known Moons
0
0
Axial Tilt°
0.03
177.36
Orbital Velocitykm/s
47.36
35.02
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.
Venus
- -Venus spins so slowly that its day (243 Earth days) is longer than its year (225 Earth days).
- -Venus is the hottest planet in the solar system at 462°C, despite Mercury being closer to the Sun.
- -Venus rotates in the opposite direction to most planets, so the Sun rises in the west and sets in the east.
- -The atmospheric pressure on Venus's surface is 92 times that of Earth -- like being 900 meters underwater.