Arthur Ross Hall of Meteorites reopens September 20: interview with Curator Denton Ebel

Denton Ebel is curator of meteorites in the Museum's Division of Physical Sciences and curator of the reconceptualization and rebuilding of the Arthur Ross Hall of Meteorites, which reopens September 20, 2003. He spoke with us about meteorites, the new hall, and the likelihood of a meteorite falling near you.

Q: What is a meteorite?

It's a rock from space. It's a piece of a shooting star that falls to Earth. It's a meteor when it's in the sky; when it hits the Earth it's a meteorite. Most meteorites are pieces of asteroids. A very few are comets.

Q: What do meteorites tell us?

Meteorites record the history of our solar system. When we look at disks where young stars are being formed today, the same processes are taking place that we think occurred when our Sun was born, 4 1/2 billion years ago. But here we have the actual leftovers of that process so we can deduce how our solar system originated. If you could cool the Sun into a rock you could hold it in your hand, it would have the same chemical composition as some meteorites. Because it's a universal process, we are by extension learning about all the other solar systems out there and how they might form and in particular, why is the Earth here, how do the elements necessary for life get distributed in a solar system among the planets, and then, of course, what makes some zones of the solar system habitable. Where might there be life? This is something that humans are interested in.

Q: What will be new in the Ross Hall of Meteorites?

Well, the architecture, for one thing, will be new. The ceiling will be raised to its full height, which gives you a sense of space since these are rocks from space. When you go into the halls of Gems and Minerals next door, you enter a cave-like kind of room, which is reminiscent of where those rocks come from.

When you enter the hall, you will be invited to ascend a 16-inch platform, which will exhibit the basic concepts. This is the introductory section. The raised platform will surround the central object, which is Ahnighito, the largest meteorite "in captivity," part of the Cape York meteorite. There is only one larger meteorite--in Africa, which is where it fell in Namibia--the Hoba meteorite. Two other pieces of the Cape York meteorite are also displayed in our new hall.

The hall surrounding Ahnighito has three sections addressing what meteorites tell us about the origins of our solar system, about the formation of the planets and planetary processes, and finally about how meteorites and the dynamic solar system interact with planets, particularly through impacts.

The Meteor Crater of Arizona will be highly featured in the hall with a scale model in a diorama. This is the best-preserved meteorite impact crater on the surface of the Earth, and it's 50,000 years old. It's in the Arizona desert so it's really very accessible, and we're collaborating with the people at the Meteor Crater Visitor's Center to create a really first-class model of it. It will have a cutaway section so you can see how the crater was originally shaped because it's got a lot of silt and infill in it--50,000 years is a long time.

Q: Can you describe how the hall will tie to some of the other Museum halls?

In the Museum there are several halls that deal with the physical sciences: the Cullman Hall of the Universe and the Gottesman Hall of Planet Earth in the Rose Center and the Morgan Memorial Hall of Gems and the Guggenheim Hall of Minerals. And the Ross Hall of Meteorites really fits between the Hall of the Universe and the Hall of Planet Earth. The universe is the setting in which our solar system formed. In the Hall of Meteorites, we focus on the origin of our solar system, the formation of planets, and the chemistry that underlies all of this, all through the meteorite specimens. This, in turn, provides the setting to explore the mysteries of planet Earth.

Our hall is very different from an older school of meteorites display, which would look at meteorites with a classification or nomenclature kind of approach as simply rocks that have different properties. The new hall will be much more focused on the processes and what they tell us about the larger scenario. So it's more like a hall of meteorites and planetary origins, much in the same way that a hall of vertebrate evolution differs from a hall of fossils.

Q: Can you say a little about your own research?

My research has largely been in the chemistry of how the particular components of chondrites, very primitive meteorites, actually formed in the solar nebula. Chondrites are really sedimentary rocks made up of dust and then chondrules, these round droplets that were once molten and now are little beads, many containing glass, which were present in the early solar system.

I'm also working in collaboration with other scientists in looking at meteorites to see how they reflect and absorb light, like sunlight. Because one of the ways we understand the chemistry of, say, an asteroid is to look at all the wavelengths of light that it reflects from the Sun and then compare that to what we can measure in the laboratory on a known specimen. So if you have meteorites A, B, and C, you can measure what their spectra look like in ultraviolet or the infrared or visible light ranges. And then with our satellites and our spacecraft and our Earth-based telescopes we can do the same measurements of remote objects and we can say it looks like A or it looks like B or C. And in that way, if it looks like a duck, and it quacks like a duck ... we can say to some degree what asteroids far away look like and what they might be.