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Phobos and Deimos are both small for moons — about 14 and 7.7 miles (22.5 and 12.4 kilometers) wide, respectively — and sort of potato-shaped. Compared to other satellites in the solar system, they look more like asteroids. As a result, astronomers previously hypothesized that these moons were asteroids captured by Mars' gravitational pull. ...previous research suggested that Phobos and Deimos would have relatively irregular orbits. In reality, these moons have nearly circular orbits positioned near the Martian equator. ... huge impact that previous research suggested created the gigantic Borealis basin in the northern lowlands of Mars, which covers two-fifths...

A volcano on Mars half the size of France spewed so much lava 3.5 billion years ago that the weight displaced the Red Planet's outer layers, according to a study released Wednesday. Mars' original north and south poles, in other words, are no longer where they once were. The findings explain the unexpected location of dry river beds and underground reservoirs of water ice, as well as other Martian mysteries that have long perplexed scientists, the lead researcher told AFP. "If a similar shift happened on Earth, Paris would be in the Polar Circle," said Sylvain Bouley, a geomorphologist at...

Did a giant impact create the two faces of Mars? 16:29 15 March 2007 NewScientist.com news service David Shiga, Houston Mars's northern hemisphere is lower in elevation – by about 5 kilometres – than its southern hemisphere (see image below). This coloured topographical map shows low elevations in blue and high elevations in yellow and red. The map is centred on a latitude of 55° north (Illustration: Mike Caplinger/MSSS) Mars's southern hemisphere is higher and more heavily cratered than the northern hemisphere, suggesting it is older terrain. The two low elevations (blue) in this map, which is centred on the...

Jafar Arkani-Hamed of McGill University discovered that five impact basins--dubbed Argyre, Hellas, Isidis, Thaumasia and Utopia--form an arclike pattern on the Martian surface. Three of the basins are well-preserved and remain visible today. The locations of the other two, in contrast, were inferred from measurements of anomalies in the planet's gravitational field... a single source--most likely an asteroid that was initially circling the sun in the same plane as Mars--created all five craters. At one point the asteroid passed close to the Red Planet... and was broken apart by the force of the planet's gravity. The resulting five pieces subsequently...

New Theory: Catastrophe Created Mars' Moons By Leonard David Senior Space Writer posted: 07:00 am ET 29 July 2003 PASADENA, California – The two moons of Mars – Phobos and Deimos – could be the byproducts of a breakup of a huge moon that once circled the red planet, according to a new theory. The capture of a large Martian satellite may have taken place during or shortly after the formation of the planet, with Phobos and Deimos now the surviving remnants. Origin of the two moons presents a longstanding puzzle to which one researcher proposed the new solution at...

Asteroid Vesta: The 10th Planet? Discovery Brightens Odds of Finding Another Pluto Nemesis: The Million Dollar Question HOUSTON, TEXAS -- Our solar system may have had a fifth terrestrial planet, one that was swallowed up by the Sun. But before it was destroyed, the now missing-in-action world made a mess of things. Space scientists John Chambers and Jack Lissauer of NASA's Ames Research Center hypothesize that along with Mercury, Venus, Earth, and Mars -- the terrestrial, rocky planets -- there was a fifth terrestrial world, likely just outside of Mars's orbit and before the inner asteroid belt. Moreover, Planet V...