Added 1 new A* page:A 56 foot / 17 meter asteroid will pass within 59,000 miles / 95,000 kilometers of the Earth today (Friday, I mean), according to this article, which mentions that that distance is about a quarter of the distance from Earth to the Moon. There will be live web broadcasts and so forth if you're into that kind of thing. This asteroid was only just discovered on October 4th! And another, even bigger asteroid already went by this week, although farther out: "On Sunday (Oct. 7), an even larger space rock — the 100-foot-wide (32-meter) asteroid 2012 TV —passed Earth at a range of 158,000 miles (255,000 km), or about 0.7 times the distance from Earth to the moon. The moon is on average about 238,000 miles (383,000 km) from Earth."|
A batch of asteroids originating from Mars landed in the Moroccan desert last July; they're called the "Tissint" asteroids after the village near their landing spot. According to this new article, scientists examining one have found its primarily basalt and olivine (an olive-green crystal) structure surprisingly shows that it contains materials from both the surface and interior of Mars; one conjecture is that "the rock's cracks and fissures were infiltrated by fluids washing down from the Red Planet's surface."
The asteroid also contains black glass, and, sealed inside that glass, bubbles containing small amounts of the Martian atmosphere; that means that those bubbles survived the cataclysmic event that blew them into space, the hot plunge through Earth's atmosphere and the landing in the Moroccan desert, and the ~700,000 years of drifting through space in between; that age was calculated by measuring the asteroid's content of certain isotopes of helium, neon and argon, which are presumed to have been created by cosmic ray collisions in interplanetary space.
3/4ths of all known Martian asteroids have been dated to 700,000 years in space, in fact, suggesting they were all created in some energetic event on Mars at that time.