Term: | Venus |
Definition: |
The second planet from the Sun, at a mean distance of roughly 108.21 x 10^6 km (0.72 astronomical units). The greatest elongation of Venus is about 47°, making it visible at most about 3 hours after sunset or before sunrise. Venus has the most circular orbit of any planet in the solar system. Venus is only slightly smaller than Earth (95% of Earth's diameter, 80% of Earth's mass). Its chemical composition and density are comparable to those of the Earth. It takes Venus just under 224.401 days to orbit the Sun, compared to the 365 day orbital period of the Earth. Venus' rotation is retrograde, that is it actually rotates from east to west, as opposed to west to east (prograde) which is the common rotating direction of most other planets. Seen from Venus, the sun would rise in the west and set in the east. Moreover, it takes about 244 Earth days for Venus to rotate once (sidereal rotation). This is longer than its orbital period. The length of its solar day is about 117 Earth days. Venus rotation. Its axial tilt is only three degrees, so there are no seasons on Venus. The atmosphere on the surface of Venus consists mostly of carbon dioxide, with a small trace of nitrogen. Venus has a surface pressure about 90 times that of the Earth. |