I’ve been out on a weeklong medical leave due to surgery and of course in my downtime a slew of cool astronomy events transpired. Most of you have read about Eris and Dysnomia now (the two latest solar system bodies to be named), so I won’t go into that, other than to say I think the naming is very, very clever.

What caught my eye in a pile of emailed press releases was a story about a rock found in Antarctica. You can see a large-size image of it here.

It’s a lunar meteorite, meaning it’s a rock from the Moon that fell to Earth, specifically in Antarctica. A group of researchers from Case Western Reserve University in Cleveland, Ohio, found it on December 11, 2005 on an icefield in the Transantarctic Mountains. They subsequently did some mineralogical testing on it to confirm its origin and announced their find last week.

Here’s a bit of info about the rock from the press release:

Scientists involved in classification of Antarctic finds at NASA’s Johnson Space Center and the Smithsonian Institution’s National Museum of Natural History said the mineralogy and texture of the meteorite are unusual. The new specimen is a very coarse-grained gabbro, similar in bulk composition to the basaltic lavas that fill the lunar maria, but its very large crystals suggest slow cooling deep within the Moon’s crust. In addition, the plagioclase feldspar has been completely converted to glass, or maskelynite, by extreme shock (presumably impact events). The new specimen most closely resembles another Antarctic meteorite, Asuka 881757, one of the oldest known lunar basalt samples.

Like the other lunar meteorites, MIL 05035 is a piece of the Moon that can be studied in detail in the laboratory, providing new specimens from a part of the lunar surface not sampled by the US Apollo program. Many researchers believe that Apollo visited some of the most unusual and geochemically anomalous regions of the Moon, and lunar meteorites, knocked off the surface of the Moon by random impacts, give us samples that are more representative of the Moon as a whole. The highly-shocked nature of MIL 05035 suggests an old age and may provide new constraints on the early intense bombardment of the Earth-Moon system, improving our understanding of the history of the Earth’s nearest neighbor and aiding NASA’s efforts toward a return to the Moon.

Following the existing protocols of the U.S. Antarctic meteorite program, scientists from around the world will be invited to request samples of the new specimen for their own detailed research. Details concerning initial characterization of the specimen and sample availability are available through the Antarctic Meteorite Newsletter, available on the Web at (http://curator.jsc.nasa.gov/curator/antmet/amn/amn.htm) and mailed to researchers worldwide.

Discovery of this meteorite occurred during the fourth full field season
of a cooperative effort by the National Science Foundation (NSF) and the National Aeronautics and Space Administration (NASA) to enhance recovery of rare meteorite types in Antarctica, in the hopes new martian samples would be found.

So, how do rocks from the Moon get to Earth? As you might have figured out from the press release segment, bombardments and collisions knock rocks off of one body and send then careening through space. Eventually, if orbits match, those rocks stray into Earth’s orbit and come to rest on our planet. Rocks from Mars have also made the trip, taking a little longer than rocks from the Moon. No matter where they come from, however, meteorites give us fascinating glimpses into their parent bodies and into their histories.

This rock appears to be evidence from early in the Moon’s formative period, when molten lavas were cooling deep beneath the surface. How this particular rock got blasted loose and sent on its way to Earth is a story waiting to be told. I suspect it will involve a massive impact and tremendous outbursts of rock from the Moon.