Mercury
CosMos Astronomy - Southern Hemisphere
"Throughout these infinite orbs of mingling light,
Of which yon earth is one, is wide diffused
A Spirit of activity and life,
That knows no term, cessation, or decay."
Percy Bysshe Shelley, "Queen Mab"
MERCURY DATA
Distance from Sun:
Aphelion 69,816,900 km
Perihelion 46,001,200 km
Equatorial Diameter:
4,880 km
Mass:
3.3022Ă—1023 kg (0.055 Earths)
Composition:
42% Molecular oxygen
29.0% sodium
22.0% hydrogen
6.0% helium
0.5% potassium
0.5% other trace elements
Moons:
0
Orbital Period:
87.96 days
Rotational Period:
58.64 days
Apparent magnitude:
-2.6 to +5.7
Angular diameter:
4.5" to 13.0"
Details of rise and set as well as relevant monthly information can be found on the Sky This Month page.
VIDEOS:
MESSENGER becomes the first spacecraft to orbit Planet Mercury - On March 17, 2011 (March 18, 2011, UTC), MESSENGER will become the first spacecraft ever to enter Mercury's orbit. The probe will continue to orbit the planet once every 12 hours for the duration of its primary mission.
Nasa video: New images from outerspace shed light on mystery of planet Mercury's origin - The first Nasa spacecraft to orbit Mercury sends back photographs that have left scientists questioning what they know about the solar system's smallest planet.
LATEST NEWS:
MESSENGER's First Image Ever Taken From Mercury Orbit.
This image is the first ever obtained from a spacecraft in orbit about the Solar System's innermost planet. Over the subsequent six hours, MESSENGER acquired an additional 363 images before downlinking some of the data to Earth.
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MESSENGER Begins Historic Orbit Around Mercury.
At 9:10 p.m. EDT, engineers in the MESSENGER Mission Operations Center at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., received the anticipated radiometric signals confirming nominal burn shutdown and successful insertion of the MESSENGER probe into orbit around the planet Mercury.
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Mercury's Surprising Core
Mercury's core occupies a large fraction of the planet, about 85% of the planetary radius, even larger than previous estimates. Because of the planet's small size, at one time many scientists thought the interior should have cooled to the point that the core would be solid.
However, subtle dynamical motions...signify an active core dynamo, indicate that the planet's core is at least partially liquid.
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CURRENT SPACECRAFT MISSION
MESSENGER Spacecraft - Images and information about this very exciting mission.