The Moon Falls to Earth

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.

Where in the Cosmos do You Want to Go?

Distant black hole, courtesy National Observatory of Japan, Subaru Telescope.

I’ve always wanted to be a space traveler, ever since I was a kid. The first place I remember wanting to visit was Saturn because I saw a picture of it in a book. It was such an alien-looking place.

Later on, as I grew older, I focused on Mars. Not sure why, but it was a great kids’ game to play “search for monsters on Mars” in the fields near our house. When I outgrew that it was the mid-60s and NASA was sending people in orbit around Earth and testing for the Apollo missions. Then I guess I wanted to go to the Moon.

Lately, I’ve been doing more work (writing and editing) about objects out as far in the universe as we can detect. These objects are galaxies, and some of them exist at a time when the universe was perhaps 700 to 800 thousand years old. That’s pretty darned early for a galaxy, given the current state of thought about galaxy evolution. But, if we’re seeing them that far back, then we’ll have to adjust our theories about how and when galaxies first formed. That’s the way science works. You observe it, then you explain it.

There are also black holes out there, not quite as far as the most distant galaxy, but darned close.

So, now I want to go to the most distant reaches of the universe and sample what happened back at the time when those distant galaxies and that black hole formed. Because, as you know, farther out in space takes you further back in time.

Of course, the best way for me to explore that era is to follow along as astronomers look farther out there, searching for the birth of the universe 13.7 billion years ago. It’s amazing to me, as that little kid who couldn’t wait to get to Saturn, that we can now see so far out in the cosmos.

So, where do YOU want to go?

Seven Sisters

Pleiades courtesy the Cassini spacecraft

Well this is kind of cool. The Cassini spacecraft orbiting Saturn took a fabulous view of the Pleiades as a “calibration” test for its camera electronics.

You can see some of the nebulosity that makes up the reflection nebula around several of the hundreds of stars that make up the Pleiades. It’s a nice, clear shot that I imagine lots of amateur astrophoto enthusiasts would love to get.

The Pleaides is one of my favorite clusters to watch, and every year I await its appearance in our autumn skies. It’s such a famous cluster and many cultures have stories about it in their star-lore. A few years ago I wrote a planetarium show that included the lore of the Pleiades in one section and I had a blast digging out stories like the one about the hen and her chicks, the seven sisters, the seven maidens, the little eyes of the heavens, the herd of camels, the Japanese name “Subaru,” and many, many others. One of the best write-ups was in a book called Burnham’s Celestial Handbook, Vol. 3, where the author compiled a culturally rich guide to this cluster. While the book is in need of updating with some more recent scientific discoveries, it’s still a treasure trove of information.

The Pleiades come in for a LOT of attention from fringe believers who think that some ancient civilization is visiting us from the Pleiades and bringing “enlightenment” and other useful goodies like using mind energy to go into other realms. It’s all very amusing, and useful to distinguish people who are interested in science from those who will believe anything if somebody plasters a mysterious astronomy-sounding name on it.

Truth is, the Pleiades are all hot young blue stars that formed sometime over the last 100 million years is too young for a star to have formed any planets around it (provided there’s anything left over from the starbirth sequence to form planets). So, if there’s a planet out there full of loving, helpful beings who are beaming their thought energy toward us, nobody’s seen it yet. The evidence just isn’t there.

This doesn’t mean the Pleiades aren’t an interesting bunch to study. There ARE brown dwarfs among the Pleiades stars, but these aren’t planets. They’re substellar objects that are somewhere between a giant planet and a small star, and they do NOT have nuclear fusion at their cores (as stars do). There are also white dwarfs in the cluster, which seems a little strange for such a young cluster. Most white dwarfs take longer than the life of the Pleiades to evolve. But, these white dwarfs could well be the remains of very massive stars that are born hot, live fast, die young, and leave shrunken little bodies behind to glow for millions or billions of years. Bad news for Pleiadeans believers: those stars would not have lived long enough to evolve planets with life on them either, or the planets would have been destroyed when the original stars lost much of their mass in old age. But, great news for astronomers, since this cluster gives us a great testbed to study stars at both ends of the age spectrum and categorize their chemical makeup and how they influence space around them!