Astronomers study unusual asteroid

Astronomers Study Unusual Asteroid
This image shows a model of the protoplanet Vesta, using scientists' best guess to date of what the surface of the protoplanet might look like. It was created as part of an exercise for NASA's Dawn mission involving mission planners at NASA's Jet Propulsion Laboratory and science team members at the Planetary Science Institute in Tuscon, Ariz. Credit: NASA/JPL-Caltech/UCLA/PSI

A space mission will soon visit an unusual asteroid called Vesta that may turn out to not be an asteroid at all, but a minor planet.

You've heard of Pluto, once a full-scale planet that astronomers now classify as a dwarf planet. Now meet 4 -- or Vesta for short -- an that may not be a real asteroid.

The 330-mile diameter object sits in the asteroid belt, a collection of large and small pieces of rubble that circles the sun between the orbits of the planets Mars and Jupiter. But Vesta, numbered 4 because it was the fourth member of the asteroid belt to be discovered, is larger than most of its asteroid companions and also differs from them geologically.

An unmanned called Dawn is now heading for Vesta to explore those differences.

"There are at least two classes of objects that have been called asteroids," said Thomas McCord, director of the Bear Fight Institute in Winthrop, Washington. "The real asteroids are broken up pieces of rock 100 kilometers (62 miles) in diameter or smaller. The others are more like small planets."

In addition to Vesta those others include Ceres, the largest asteroid and first to be discovered, and Pallas, the second asteroid to be spotted. Ceres is now classified as a dwarf planet like Pluto.

However, Vesta is unique in several respects. It is denser than Ceres and Pallas. It also appears to be differentiated into a rocky surface and an , like the terrestrial planets Earth, Mars, and Venus. And it is continually shedding material from its surface as a result of collisions with small asteroids.

"There are little pieces of Vesta all over the ," said Tim Spahr, director of the Minor Planet Center at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass.

Astronomers have already had a close-up view of some of those pieces because some of them have landed on the Earth's surface as meteorites. Scientists recognized their provenance by studying their spectra, which indicates their chemical composition, and comparing them with Vesta's spectrum.

Ceres and Pallas, which differ from Vesta geologically, shed less debris. "Whatever they are made of doesn’t travel well," said Christopher Russell, professor of geology at the University of California, Los Angeles.

Telescope observations by McCord in 1972 revealed that Vesta’s surface consists of a rock called basalt, which on Earth is made from cooled magma.

"The basalt would make it unique in that category of objects," Spahr said.

"We think of it as a very large asteroid that is very Earthlike -- called Vesta, the smallest terrestrial planet," Russell said.

Astronomers believe that Earth and similar planets formed when a series of small bodies coalesced. "We think that these bodies were around in large numbers and came together to build planets," Russell explained.

McCord added that the problem with Vesta is that "it didn't find a companion to become a piece of a bigger object that would coalesce with other companions." So it remained by itself, a kind of time capsule from an early era in our solar system.

Russell oversees the Dawn mission with McCord as a co-investigator. Dawn is scheduled to reach Vesta in July and spend a year in orbit, using an infrared spectrometer, a camera, and a gamma ray detector to explore Vesta's composition.

The team expects to determine whether basalt uniformly covers Vesta's surface and where on the surface meteorites originate. The mission will also probe a large crater in Vesta's southern hemisphere that has exposed its interior.

"If it is really differentiated, we would see minerals at depths similar to what we see in the Earth’s mantle," McCord said.

When it leaves Vesta, the Dawn mission will travel to Ceres, which is larger, rounder, and wetter than Vesta.

By studying the contrasts between the two objects, astronomers hope to obtain clues to the ways in which the evolved.

"We're going to try to understand what the building blocks of the early solar system were like," Russell said. "It's really about tracing our family tree and understanding where we come from."

Will the findings lead astronomers to reclassify Vesta? Probably not. At the same 2006 meeting where Pluto was demoted to minor planet status, was designated one of 269,644 minor planets.

"It was given minor planet number 4, and nobody has worried about [its classification] since," Spahr said.

Explore further

When is an asteroid not an asteroid?

Provided by Inside Science News Service
Citation: Astronomers study unusual asteroid (2011, April 15) retrieved 24 April 2019 from
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

Feedback to editors

User comments

Apr 16, 2011
When I was very young I remember a nagging emptiness and no coherent, logical or complete explanation from the "bible" or church for electronics, physics or any other science I was interested in. Years later my daughter experianced the same emptiness when a church tried to tell her there were never any dinosaurs (her interest). I wonder if the people who think it is okay to preach on a science site would like it if everyone at this site went to religion sites and posted science and evolution all the time ,I bet they wound say "How rude and inconsiderate!".

Apr 16, 2011
So kevin, you're advocating leaving these questions alone and perpetuating the ignorance which has been espoused by the religious community since its inception? The discoveries made by the scientific community don't fill me with emptiness, they fill me with wonder and awe. The scientific explanations for even the 'ordinary' are so much more amazing than the dogma handed down through the church.

Apr 16, 2011
Let me be quite frank: The evidence CLEARLY contradicts the speculations

Let me be quite frank: read the article, study some science, do some math - then you will see that you're wrong.

In the beginning there was a lot of (smallish) stuff about - so the effect of matter coalescing into separate entities outweighed the effect of grains hitting and carrying matter away.

Now hat the matter has mostly clumped into bodies (like planets, moons, comets and asteroids) the coalescing has all but stopped (for lack of further material) and the effect of matter abrasion by the occasional collision or outgassing is predominant.

You have to stop believing that there is only ever one mechanism at work. We live in a dynamic universe where stuff can actually CHANGE.

Just how did the bodies come together to coalesce?

Gravity? You know...that force that keeps you (unfortunately) from flying off into space?

Apr 16, 2011
You know the sad thing is that most people that jump on science websites and start spouting off the message of God don't seem to realize that science and religion are both asking the same questions they are just using different methods to answer them. Grow up all of you jesus freaks and stop trying to make yourselves sound intelligent and actually take the time and read something before you decide to call it outlandish and nonsense.

Apr 16, 2011
Let me be quite frank: The evidence CLEARLY contradicts the speculations - and that is what it is: speculations. Nobody knows how the planets were formed, hence anything said about such a formation is just speculation at this stage. Just how did the bodies come together to coalesce? No one knows and no one is saying either.
The accretion hypothesis of interstellar matter was tested and confirmed during the Apollo missions. You need an education.

Apr 16, 2011
This comment has been removed by a moderator.

Apr 16, 2011
@PhysOrg moderator(s)...

Can you PLEASE do something about the massive amounts of spam? I report each and every occurrence that I see, but they're never pulled and as a result, we're now seeing not one spam every 10 articles or so, but now up to 3 spams per article. Please do something about this.

Apr 16, 2011
Kevin is a fucking turdburglar. Since there are THREE consecutive ads at the top of this page I don't really have any fear of this being deleted. And if so, LOL.

LMAO! You're probably right about the moderators. I fived you AND reported you... just to prove your point! :)

Apr 16, 2011
Nobody knows how the planets were formed, hence anything said about such a formation is just speculation at this stage [..] the universe was created by God as specified in the bible

So, which is it?

Also, I've asked you this before and you've never answered it. The Bible (notice, I capitalized it and you didn't, BTW) says that the universe was created ~6000 years ago. If so, why do we see objects BILLIONS of light years away? Answer that for credibility.

Also, asked to you so many times we've all lost count and you've NEVER answered it: Why didn't the world wide flood affect the Egyptians?

As a fellow Conservative, I respectfully request that you stop posting uneducated crap that counters observation, math, and logic AND ANSWER THE $#@! QUESTIONS!!!!

To my science colleagues here: Kevin's an example of a religious zealot, NOT an example of an intellectual Conservative. Though, he may be politically Conservative, his religious dogma is a completely different animal.

Apr 16, 2011
Just how did the bodies come together to coalesce? No one knows and no one is saying either.

Wrong! Example: There's an awesome "home" video made by an astronaut on-board the space shuttle. He had a bag of rice or something and was shaking it and the particles started sticking together. He didn't think anything of it, but showed it to a scientist friend of his a year or two later who recognized the importance of this. Particles scraping against each other in zero gravity produce static electricity which causes them to clump together. This was the first physical demonstration of the process actually taking place. After clumps of just a few pounds formed, there's enough gravity to pull in other particles which then form into large, astronomical bodies like asteroids and planets.

I saw this video several times on Discovery Channel, I think (or the Science Channel). If someone can find this online, I'd really appreciate a link, since this comes up so often.

Apr 18, 2011
can rocks pdoduce enough static electricity though for them to stick together? as for the asteroid belt. they think a whole planet WAS there but got imploded by jupiter and some of the asteriod belt got sucked up by it. (yes, no?)

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more