Like the Earth's Moon, Mercury is [ http://nssdc.gsfc.n…] scarred with craters testifying to an intense bombardment during the early history [ http://antwrp.gsfc.…] of the Solar System. In 1974, the Mariner 10 [ http://pds.jpl.nasa…] spacecraft surveyed this innermost planet [ http://nssdc.gsfc.n…MC_Mariner_10_page1. html ] up close, producing the only detailed images of its tortured surface. In the above mosaic [ http://nssdc.gsfc.n…m10_aom_3_e.html ] the bright rays emanating from the 45 kilometer wide Degas crater almost appear to be painted on [ http://sunsite.unc.…]. The rays consist of light colored material blasted out during the crater's formation. Craters [ http://www.lpi.usra…craterstructure.html ] older than Degas are covered by the ray material while younger craters are seen superimposed on the rays. Mercury's [ http://www.seds.org…mercury.html ] gravity and density are about [ http://www.whfreema…PLANET.HTM ] twice that of Earth's [ http://nssdc.gsfc.n…planet_table_ratio.h tml ] Moon so such bright ray craters [ http://www.sunlink.…] on the lunar surface tend to be much larger. NASA plans to launch MESSENGER [ http://sd-www.jhuap…MESSENGER/ ] to the least explored [ http://www.soest.ha…MercuryUnveiled.html ] terrestrial planet in 2004.
Explanation
Like the Earth's Moon, Mercury is [ http://nssdc.gsfc.n…] scarred with craters testifying to an intense bombardment during the early history [ http://antwrp.gsfc.…] of the Solar System. In 1974, the Mariner 10 [ http://pds.jpl.nasa…] spacecraft surveyed this innermost planet [ http://nssdc.gsfc.n…MC_Mariner_10_page1. html ] up close, producing the only detailed images of its tortured surface. In the above mosaic [ http://nssdc.gsfc.n…m10_aom_3_e.html ] the bright rays emanating from the 45 kilometer wide Degas crater almost appear to be painted on [ http://sunsite.unc.…]. The rays consist of light colored material blasted out during the crater's formation. Craters [ http://www.lpi.usra…craterstructure.html ] older than Degas are covered by the ray material while younger craters are seen superimposed on the rays. Mercury's [ http://www.seds.org…mercury.html ] gravity and density are about [ http://www.whfreema…PLANET.HTM ] twice that of Earth's [ http://nssdc.gsfc.n…planet_table_ratio.h tml ] Moon so such bright ray craters [ http://www.sunlink.…] on the lunar surface tend to be much larger. NASA plans to launch MESSENGER [ http://sd-www.jhuap…MESSENGER/ ] to the least explored [ http://www.soest.ha…MercuryUnveiled.html ] terrestrial planet in 2004.
