Red Planet's Ancient Equator Located

Scientific American (online) ^ | April 20, 2005 | Sarah Graham

[SunkenCiv]

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 slammed into Mars along its then equator. The center of the circle inscribed by the five craters, which marks the planet's ancient south pole, lies at present day latitude -30 and longitude 175.

[SunkenCiv]

update.

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[Grizzled Bear]

Ooooookay. What tipped Mars off its' then axis?

Darksheare's fault.

[Darksheare]

I sneezed, sorry about that.

[SunkenCiv]

• Red planet's hue due to meteors, not water -- "There is something of a paradox about Mars," agrees Joshua Bandfield of Arizona State University in Tempe. His team recently showed that the planet has no large deposits of carbonates, which should have formed if giant pools of water had persisted on the surface. Bandfield suggests that liquid water must have occasionally burst out of the ground, carving channels and gullies, but that it quickly froze again in the frigid Martian climate.

[SunkenCiv]