Featured Research

from universities, journals, and other organizations

A New Twist To Dating An Asteroid

Date:
August 18, 2005
Source:
Northwestern University
Summary:
It turns out you can't judge an asteroid by its cover, according to a recent study in the journal Nature. Or at least you can't accurately date a certain asteroid called 433 Eros by counting the impact craters on its surface -- the traditional method for determining an asteroid's age.

Asteroid 433 Eros.
Credit: Image courtesy of NASA

It turns out you can't judge an asteroid by its cover, according toa recent study in the journal Nature. Or at least you can't accuratelydate a certain asteroid called 433 Eros by counting the impact craterson its surface -- the traditional method for determining an asteroid'sage.

Peter Thomas, a senior research associate in astronomy at CornellUniversity and lead author on the paper, and Mark Robinson, researchassociate professor of geological sciences at Northwestern University,analyzed images of Eros gathered four years ago by the Near EarthAsteroid Rendezvous mission. The mission mapped the 20-mile-long,potato-shaped asteroid and its thousands of craters in detail. The tworesearchers focused on a large impact crater, known as the Shoemakercrater, and a few unusual crater-free areas.

In the Nature article, Thomas and Robinson show that the asteroid'ssmooth patches can be explained by a seismic disturbance that occurredwhen a meteoroid crashed into Eros, shaking the asteroid and creatingShoemaker crater. The shaking caused loose surface material to fillsome small craters, essentially erasing craters from approximately 40percent of Eros' surface and making the asteroid appear younger thanits actual age.

The fact that seismic waves were carried through the center of theasteroid after the impact shows that the asteroid's interior iscohesive enough to transmit such waves, say the authors. And thesmoothing-out effect within a radius of up to 5.6 miles from the4.7-mile Shoemaker crater -- even on the opposite side of the asteroid-- indicates that Eros' surface is loose enough to get shaken down bythe impact.

Asteroids are small, planet-like bodies that date back to thebeginning of the solar system, so studying them can give astronomersinsight into the solar system's formation. And while no asteroidscurrently threaten Earth, knowing more about their composition couldhelp prepare for a possible future encounter. Eros is the mostcarefully studied asteroid, in part because its orbit brings it closeto earth.

Thomas and Robinson considered various theories for the regions ofsmoothness, including the idea that ejecta from another impact hadblanketed the areas. But they rejected the ejecta hypothesis whencalculations showed an impact Shoemaker's size wouldn't create enoughmaterial to cover the surface indicated. And even if it did, they add,the asteroid's irregular shape and motion would cause the ejecta to bedistributed differently. In contrast, the shaking-down hypothesis fitsthe evidence neatly.


Story Source:

The above story is based on materials provided by Northwestern University. Note: Materials may be edited for content and length.


Cite This Page:

Northwestern University. "A New Twist To Dating An Asteroid." ScienceDaily. ScienceDaily, 18 August 2005. <www.sciencedaily.com/releases/2005/08/050805180543.htm>.
Northwestern University. (2005, August 18). A New Twist To Dating An Asteroid. ScienceDaily. Retrieved October 21, 2014 from www.sciencedaily.com/releases/2005/08/050805180543.htm
Northwestern University. "A New Twist To Dating An Asteroid." ScienceDaily. www.sciencedaily.com/releases/2005/08/050805180543.htm (accessed October 21, 2014).

Share This



More Matter & Energy News

Tuesday, October 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Thanks, Marty McFly! Hoverboards Could Be Coming In 2015

Thanks, Marty McFly! Hoverboards Could Be Coming In 2015

Newsy (Oct. 21, 2014) If you've ever watched "Back to the Future Part II" and wanted to get your hands on a hoverboard, well, you might soon be in luck. Video provided by Newsy
Powered by NewsLook.com
Robots to Fly Planes Where Humans Can't

Robots to Fly Planes Where Humans Can't

Reuters - Innovations Video Online (Oct. 21, 2014) Researchers in South Korea are developing a robotic pilot that could potentially replace humans in the cockpit. Unlike drones and autopilot programs which are configured for specific aircraft, the robots' humanoid design will allow it to fly any type of plane with no additional sensors. Ben Gruber reports. Video provided by Reuters
Powered by NewsLook.com
Graphene Paint Offers Rust-Free Future

Graphene Paint Offers Rust-Free Future

Reuters - Innovations Video Online (Oct. 21, 2014) British scientists have developed a prototype graphene paint that can make coatings which are resistant to liquids, gases, and chemicals. The team says the paint could have a variety of uses, from stopping ships rusting to keeping food fresher for longer. Jim Drury reports. Video provided by Reuters
Powered by NewsLook.com
Portable Breathalyzer Gets You Home Safely

Portable Breathalyzer Gets You Home Safely

Buzz60 (Oct. 21, 2014) Breeze, a portable breathalyzer, gets you home safely by instantly showing your blood alcohol content, and with one tap, lets you call an Uber, a cab or a friend from your contact list to pick you up. Sean Dowling (@SeanDowlingTV) has the details. Video provided by Buzz60
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins