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Venus
is the second planet from the sun and passes closer to the Earth than any other
planet at a minimum distance of 108 million km. It can reach magnitudes of -4.7,
which is much brighter than the next planet, Jupiter. This is because of its dense
atmosphere, which reflect about 65% of the light hitting them.
Venus is the Roman god of love and beauty.
Venus' orbit is the least eccentric of all the planets,
but unnusually, the planet itself spins slowly and in reverse compared with the
other
planets. A Venusian day is 243 Earth days, whilst a year is 225 days.
Venus has no moons.
|
Semimajor axis (km) |
108.21x106 |
|
Perihelion (km) |
107.48x106 |
|
Aphelion (km) |
108.94x106 |
|
Mean orbital speed (km s-1) |
35.02 |
|
Sidereal orbit period (days) |
224.701 |
|
Tropical orbit period (days) |
224.695 |
|
Synodic period (days) |
583.92 |
|
Length of day (hours) |
2802 |
|
Sidereal rotation period (hours) |
-5832.5 |
|
Obliquity to orbit (deg) |
177.36 |
|
|
Semimajor axis (AU) |
0.72333199 |
|
Eccentricity |
0.00677323 |
|
Inclination (deg) |
3.39471 |
|
Longitude of ascending node (deg) |
76.68069 |
|
Longitude of perihelion (deg) |
131.53298 |
|
Mean longitude (deg) |
181.97973 |
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Discoverer |
Unknown |
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Date of Discovery |
Classical |
J2000 Data from
NSSDC
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Venus has been visited on several occasions by unmanned
probes, first in 1962 by Mariner 2, then Mariner 10 (1974) in a flyby to Mercury
and later by Pioneer Venus (1978) and also the USSR's landers Venera 7 in 1970 and
Venera 9 in 1975. Most recently, Magellan (launched 1989) mapped 98% of Venus' surface.
Venus is very similar to the
earth in both
size (650km less) and mass and it is probable that it's core is similar too. It
seems to have many small volcanoes to relieve the stress of the magma beneath the
crust rather than just at the plate boundaries as on the Earth. Magellan data on
Venus' gravitational field suggests the planet has a thicker crust than was previously
thought.
The clouds of Venus rotate once every four days in a retrograde
direction as a result of strong winds. They are composed largely of (80% concentration)
sulphuric acid. The surface is sprayed with acid rain as a result. It was only possible
to detect the length of the Venusian day by radar as the clouds entirely engulf
the surface.
Only in the 1950s, by the planet's radio emissions, did
astronomers get any clue as too the surface conditions. It turned out that Venus
is hot, hotter than boiling water, which was confirmed when the USSR's Venera 4
was destroyed due to the temperature and pressure. Surface temperature was found
to be about 750K and the pressure 90 times that of Earth. This is because of the
greenhouse effect, the sunlight reaching the surface is absorbed and reemitted by
the planet, only to be absorbed like a blanket by the carbon dioxide atmosphere
and sulphuric acid clouds.
There are several continental areas, notably Ishtar Terra,
the size of the USA and the largest of all; Aphrodite Terra. There is a large mountain
range, Maxwell Montes, reaching 12km above the surroundings in Ishtar Terra, while
Aphrodite Terra has a vast system of valleys spanning thousands of kilometres.
|
Mass (kg) |
4.8685x1024 |
|
Equatorial radius (km) |
6051.8 |
|
Polar radius (km) |
6051.8 |
|
Mean density (kg m-3) |
5243 |
|
Equatorial surface gravity (m s-2) |
8.87 |
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Escape Velocity (km s-1) |
10.36 |
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Black-body temp (K) |
231.7 |
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Solar intensity (W m2) |
2613.9 |
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Natural satellites |
0 |
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