First craters on Mars spotted 50 years ago

Excerpt from the August 7, 1965, issue of Science News Letter

The surface of Venus

SPOTTED  Using radar, spacecraft have cut through the Venusian clouds to snap images of craters on the planet’s surface. Mead crater (shown) is the largest on Venus at 280 kilometers across.


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Craters found on Mars — Astronomers are speculating whether the surfaces of other bodies in the solar system, besides Earth’s moon and Mars, are covered with craters from meteorite strikes. The surface of Venus may never be revealed because of its cloud cover.… The Mariner 4 photographs of Mars, man’s first close-up pictures of another planet, revealed the totally unexpected fact that the Martian surface, like Earth’s moon, is peppered with craters. — Science News Letter, August 7, 1965


Earth’s moon and Mars are not alone in their pockmarked appearances. Spacecraft have snapped pictures of impact craters on Mercury, Venus and many of the moons of Jupiter, Saturn and Uranus (see slideshow below). The gas giants, including Neptune, have no hard surfaces. But Jupiter’s gassy body has shown signs of bruising after collisions with comets and other debris (SN Online: 6/4/10). The far-flung worlds of Pluto and its largest moon, Charon, have surprisingly few craters, suggesting both are geologically active, or recently were.

COVERED IN CRATERS Mercury’s Rembrandt basin, discovered in 2008, is dotted with smaller impact craters, suggesting the basin is one of the youngest on the planet. Carnegie Institution of Washington/Smithsonian Institution/JHUAPL/NASA
Earth's surface
LEAVING A MARK At roughly 1.2 kilometers across, Meteor Crater in Arizona is a pockmark that isn’t easily ignored. It served as a training ground for Apollo astronauts in the 1960s and 1970s. Shane.torgerson/Wikimedia Commons (CC BY 3.0)
Moon's surface
BIG BASIN On the farside of the moon is Aitken crater. Shown here in an Apollo 17 image, this scar on the lunar surface is 135 kilometers across. NASA
Iapetus, a moon of Saturn
PUNCHING IN Gerin crater on Saturn’s moon Iapetus is 445 kilometers across and was partially destroyed by a later impact. NASA
DEEP DEPRESSIONS This false-color view of Mars reveals the eye-shaped Hellas impact basin (purple, lower left) and Borealis basin (blue, upper right). Covering roughly 40 percent of the planet, Borealis basin may be the largest impact basin in the solar system. JPL/NASA

Ashley Yeager is the associate news editor at Science News. She has worked at The Scientist, the Simons Foundation, Duke University and the W.M. Keck Observatory, and was the web producer for Science News from 2013 to 2015. She has a bachelor’s degree in journalism from the University of Tennessee, Knoxville, and a master’s degree in science writing from MIT.

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