Meteorites can reveal a lot about the composition and formation of their parent bodies, but such postcards from beyond come with no return address, making their provenance difficult to establish. Often, astronomers must observe the object's inbound trajectory and then trace its orbit backward through time to nail down the region of space or the specific parent body that a meteorite sprang from. (In one unprecedented case announced in March, a group of researchers had the added advantage of having spotted the object in space before its atmospheric entry.)

In 2007 a sky-watching program known as the Desert Fireball Network tracked a streak of light over Australia that led researchers to meteorite fragments on the ground. Through an analysis of its composition and orbital characteristics, the meteorite, known as Bunburra Rockhole, has revealed itself to be out of the ordinary, one of a small family of its kind to not originate from a large asteroid known as Vesta. The research, led by meteoritic and planetary scientist Philip Bland of Imperial College London, appears in this week's Science.

An earthquake rattled northern California at 10:40 A.M. (Pacific Daylight Time) today, centered 11 miles (18 kilometers) north of the city of Morgan Hill and 16 miles (25 kilometers) east by southeast of San Jose. The U.S. Geological Survey (USGS) assessed the initial magnitude of the quake as 4.3 on the Richter scale.

According to the San Francisco Chronicle, the earthquake could be "felt throughout the Bay Area and beyond from Santa Rosa and Napa on the north, Soledad on the south, and Groveland in Tuolumne County on the east." The CBS affiliate in Sacramento reported that the "Morgan Hill police dispatcher said there were no immediate reports of injuries or damage"; the dispatcher told the Associated Press that the tremors were "short, but strong."

A new, high-resolution topographic map of the lunar surface indicates that the outer layers of the moon are likely bone dry. The new data, obtained from a laser-mapping instrument onboard the Japanese SELENE satellite, also known as Kaguya, shows that the moon's surface is rigid, not buoyant and flexible as would be expected if a significant amount of water flowed underneath it.

"The surface can tell us a lot about what's happening inside the moon, but until now mapping has been very limited," study co-author C. K. Shum, a professor of earth sciences at Ohio State University, said in a statement. "For instance, with this new high-resolution map, we can confirm that there is very little water on the Moon today, even deep in the interior. And we can use that information to think about water on other planets, including Mars."

Dozens of remnants of the fireball that lit up Canadian skies last month have turned up in western Canada, according to a researcher leading the hunt. Alan Hildebrand, a professor of geology and geophysics at the University of Calgary, told ScientificAmerican.com today that around 50 pieces of the object have now been found, the largest of which weighs roughly 28.5 pounds (13 kilograms). The meteor's brilliant trajectory was caught on film November 20 by unsuspecting videographers.

Over the weekend multiple news outlets reported that the search team had discovered remnants of the meteor near Lloydminster, a town of about 25,000 that straddles the border between the provinces of Alberta and Saskatchewan. The Associated Press reports that a meteorite collector and dealer in Tucson, Ariz., had offered a bounty of up to $9,700 for the first fragment weighing at least 2.2 pounds (one kilogram). Hildebrand says he's not sure if any of the pieces are for sale but that he has informed the landowners where fragments were found of their potential value. Meteorites act as postcards from space in a sense, providing clues to the evolution of the solar system and the composition of distant objects.

At least 150 people are dead and hundreds hurt after two strong earthquakes rattled southwest Pakistan this morning.

The first, a magnitude 6.4 quake, was centered 35 miles (60 kilometers) northeast of Quetta at 4:09 this morning (7:09 P.M. Tuesday Eastern time), according to the U.S. Geological Survey. A second magnitude 6.2 temblor struck in the same spot about 12 hours later, at 4:32 P.M. (7:32 A.M. ET), the agency reports.

"It was a shallow earthquake, which is very destructive," Qamar Zaman Chaudhry, the director general of Pakistan Meteorological Department, said of the first quake, according to The New York Times. "The aftershocks will be felt for a week with more or less the same intensity."

The world's oldest rock has been found along the eastern shore of Hudson Bay in northern Quebec. The rock, a chunk of ancient volcanic deposits, is around  4.28 billion years old—or 250 million years older than the previous record-holder, the Acasta gneiss in northwestern Canada. That also makes them less than 300 million years younger than the Earth itself.

"There have been older dates from Western Australia for isolated resistant mineral grains called zircons," says geochemist Richard Carlson of the Carnegie Institution in Washington, who dated the old stone and reported its age this week in Science. But those zircons (which contain some of the world's oldest diamonds) were not actual rock like this bedrock. "This gives us an unprecedented glimpse of the processes that formed the early crust," Carlson says.

Geologists have a disturbing message for residents slowly rebuilding their lives in China's devastated Sichuan province after May's Wenchuan earthquake: Brace for further rattling.

The quake, which measured 7.9 on the Richter scale and killed at least 70,000 people, has also put undue stress on the Xianshuihe, Kunlun and Min Jiang faults that run through the region. "We tend to think of earthquakes as relieving stress on a fault. That may be true for the one that ruptured," says Ross Stein of the U.S. Geological Survey, "but not for adjacent faults."

Using computer models, geologists report in Geophysical Research Letters that there's as much as a 71 percent chance that a quake of magnitude 6 or greater will occur in the next decade on one of these other geologic faults. There have already been several aftershocks nearly that large on the Longmen Shan fault that triggered the Wenchuan tremblor. The researchers also predict that a series of smaller earthquakes will occur on these adjacent faults.