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.

Related Articles


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 25, 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 25, 2014).

Share This



More Matter & Energy News

Saturday, October 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

IKEA Desk Converts From Standing to Sitting With One Button

IKEA Desk Converts From Standing to Sitting With One Button

Buzz60 (Oct. 24, 2014) IKEA is out with a new convertible desk that can convert from a sitting desk to a standing one with just the push of a button. Jen Markham explains. Video provided by Buzz60
Powered by NewsLook.com
Ebola Protective Suits Being Made in China

Ebola Protective Suits Being Made in China

AFP (Oct. 24, 2014) A factory in China is busy making Ebola protective suits for healthcare workers and others fighting the spread of the virus. Duration: 00:38 Video provided by AFP
Powered by NewsLook.com
Real-Life Transformer Robot Walks, Then Folds Into a Car

Real-Life Transformer Robot Walks, Then Folds Into a Car

Buzz60 (Oct. 24, 2014) Brave Robotics and Asratec teamed with original Transformers toy company Tomy to create a functional 5-foot-tall humanoid robot that can march and fold itself into a 3-foot-long sports car. Jen Markham has the story. Video provided by Buzz60
Powered by NewsLook.com
Police Testing New Gunfire Tracking Technology

Police Testing New Gunfire Tracking Technology

AP (Oct. 24, 2014) A California-based startup has designed new law enforcement technology that aims to automatically alert dispatch when an officer's gun is unholstered and fired. Two law enforcement agencies are currently testing the technology. (Oct. 24) Video provided by AP
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