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Asteroid Naming Honors Stellar Scientist 
- What's in a name?
- What’s the difference between an asteroid and a meteorite?
- Dr. McCoy’s Research

Photo portrait: Dr. Timothy J. McCoyNMNH Mineral Sciences Curator Dr. Timothy J. McCoy recently had an asteroid named for him in recognition of his research in meteoritics, the study of meteorites.  The asteroid is now known as Asteroid 4259 McCoy.  It was discovered by Dr. Bobby Bus at Cerro Tololo, Chile, in 1988.  The official citation for this naming is:

Timothy J. McCoy (b. 1964) is a curator of the national meteorite collection at the Smithsonian’s National Museum of Natural History in Washington, DC.  His research has been crucial for understanding the complex heating and melting events on the parent body of the acapulcoite and lodranite meteorites.

What’s in a name?

Asteroids are named through a detailed process, overseen by the Smithsonian Astrophysics Observatory's  Minor Planets Center.  Once an asteroid is discovered, multiple observations are needed to determine its orbit.  The asteroid then receives a provisional designation, and then a number.  The person who discovered the asteroid then proposes a name for it.  Finally, the name is approved by the International Astronomical Union.  In the past, asteroids have been named for mythological features and characters, pets, even famous musicians - such as the Beatles - but increasingly they are being named for scientists like Dr. McCoy who have made significant contributions to scientific fields related to asteroids. Of the15,000 numbered asteroids, approximately one half of them are named, and only a few thousand are named after people.  Asteroid 4259 McCoy joins three other stellar bodies named for important Smithsonian staff - - Former Secretary I. Michael Heyman, Under Secretary Dennis J. O’Connor, and former Under Secretary Constance Newman also have asteroids named in their honor. 

What’s the difference between an asteroid and a meteorite?

Asteroids are bodies of rock and iron, usually 10-50 km in diameter, in stable orbits around our solar system’s star, the Sun.  Even with the most powerful Earth-based telescopes, asteroids appear as just points of light, like stars. Most of the asteroids in our solar system are in a belt between the orbits of the planets Mars and Jupiter.  If not for the powerful gravitational pull exerted by the massive planet Jupiter, the hundreds of thousands of asteroids probably would have joined together to become a planet during the formation of our solar system.

Text highlightMeteorites are pieces of asteroids.  They break off of asteroids during chance collisions with other asteroids and can spend millions of years orbiting the sun before they fall to Earth.  As a meteorite is entering the atmosphere, it is called a “meteor” or by the better known term “shooting star”.  Meteorites range in mass from less than a gram to more than 50 tons.  The largest meteorite, estimated to weigh more than 60 tons and found in 1920, remains where it fell in Namibia. NMNH has the largest and most important museum collection of meteorites in the world.  Over 20,000 specimens from 10,000 different meteorites are in the collection.  To learn more about our collections and research in mineral sciences, click here.  Many of these meteorites were recovered in Antarctica by an effort sponsored by the Smithsonian, NASA and the National Science Foundation.  

  Photo of meteorite
Monument Draw Acapulcoite meteorite
         showing areas of accumulated, melted metals.
 

Dr. McCoy’s Research

“Meteorites are relics from the dawn of the solar system.  Asteroids are the source of meteorites - when you look at them, you are really looking at the birth of the solar system.  In studying meteorites, I’m working on understanding how the solar system originated”, says Dr. McCoy.

His research is significant because he identified the stages that meteorites undergo as they are transformed by radioactive heating.  Asteroids formed out of materials from the solar nebula, the cloud of gas and dust that produced the planets and Sun. Meteorites from these first, primitive asteroids are called “chondrites”.  As asteroids are heated by the early sun and by the radioactive elements they contain, lighter minerals rise to the surface to form a crust, while denser, metallic minerals sink to the center to form a core, the same type of differentiated structure as the Earth.  Dr. McCoy discovered meteorites that record the first stages of melting and differentiation that transform chondritic asteroids into differentiated asteroids.  Acapulcoite meteorites (named for a meteorite that fell in Acapulco, Mexico in 1976) record the first stage in the heating and melting process.  The Monument Draw acapulcoite meteorite, shown above, shows large veins of metal formed as melted material began to accumulate into larger veins and migrate through the asteroid.  Lodranite meteorites (named for a meteorite which fell in Lodran, India in 1868) are residues, the materials left behind after melted metals migrate away.  If this process proceeds to its final stage, a planet like Earth is produced, with its differentiated crust, mantle, and core. 

Dr. McCoy is continuing his research into the structure of asteroids by participating in NASA’s Near Earth Asteroid Rendezvous (NEAR) mission.  This mission, which is currently orbiting asteroid 433 Eros for a year, is mapping the geology, mineralogy and chemical composition of the surface of the asteroid.  This data should provide an even better view of how meteorites are related to one another on a body the size of an asteroid.  In the fall of 2000, look for an exhibit on the NEAR mission and its relationship to meteorites in the Constitution Avenue lobby of the Natural History Museum.


To learn more about asteroids and meteorites visit these links:

 

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