Mercury: as seen by Mariner 10 in 1974			3.1
			Mercury as seen by Mariner 10 in 1974 on its incoming (right) and outgoing (left) fly-bys. There is a slight overlap in the areas covered by these two images. Each view is constructed from a mosaic of more detailed images.
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Image Credit: NASA
Planetary Facts Equatorial radius: 2439 km Mass (relative to Earth): 0.055 Density: 5.43 g/cm3 Surface gravity:   0.38 (relative to Earth) Rotation period: 58.6 days Axial inclination: 0.1° Distance from the Sun (AU): 0.387 Orbital period: 88 days Composition of surface: rocky Mean surface temperature: 170°C Composition of atmosphere - atomic oxygen, sodium, helium, potassium Number of satellites: 0		These photomosaics of the planet Mercury were assembled from individual high-resolution images taken by Mariner 10 shortly before and after closest approach in 1974. Left photo: The sun is shining from the right, and the terminator is at about 100 degrees west longitude. Crater Kuiper, named after astronomer Gerard P. Kuiper, can be seen just below the center of the planet's illuminated side. The landscape is dominated by large craters and basins with extensive plains between craters. Right photo: The sun is shining from the left.
		David A. Rothery	Return to top of page