Astronomy Blog

Share |

NASA Weighs an Asteroid

June 14, 2012; 6:40 AM ET

NASA's Jet Propulsion Laboratory in Pasadena, Calif., has measured the mass of a nearby asteroid millions of miles away. This feat was achieved by Steve Chesley of JPL's Near-Earth Object Program Office by utilizing information from three NASA data sources, the Goldstone Solar System Radar in the California desert, the orbiting Spitzer space telescope and the NASA-sponsored Arecibo Observatory in Puerto Rico.

Chesley presented his findings Saturday, May 19, at the Asteroids, Comets and Meteors 2012 meeting in Niigata, Japan.

For Chesley to figure out the asteroid's mass, he first needed to understand its orbit and everything that could affect it including neighboring heavenly bodies and any forces that the asteroid could cause on its own.

Using remarkably accurate observations collected by astronomer Michael Nolan at Arecibo Observatory in September 2011, Arecibo and Goldstone radar observations made in 1999 and 2005, and the gravitational effects of the Sun, Moon, planets and other asteroids, Chesley was able to calculate how far the asteroid deviated from its anticipated orbit. He found that 1999 RQ36 had deviated from what the math says it should by about 100 miles in the past 12 years. The only logical explanation for this orbital change was that the space rock itself was generating a minute propulsive force known as the Yarkovsky effect.

See this blog here for more information about the Yarkovsly effect and asteroids.

According to NASA, "Asteroid 1999 RQ36 is of special interest to as it is the target of the agency's OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer) mission. Scheduled for launch in 2016, ORIRIS-REx will visit 1999 RQ36, collect samples from the asteroid and return them to Earth."

Information from NASA was used in this blog.

You can leave your comments, as well as be part of a community with discussions on any astronomy subject, such as light pollution, when you join AccuWeather's Astronomy Facebook fan page by clicking here.

We are now well over 3,500 likes on Facebook. Please tell your friends about this Facebook page and blog and have them weigh in on some exciting issues. We encourage open discussion and will never criticize any idea, and no negative conversation will be allowed. We are really trying to make this Facebook page THE place to go to for any astronomy news or discussion and your help would be GREATLY appreciated!

The views expressed are those of the author and not necessarily those of AccuWeather, Inc. or


Comments left here should adhere to the Community Guidelines. Profanity, personal attacks, and spam will not be tolerated.

More Astronomy Weather Blog

  • Eta Aquarids from Halley's Comet Peak Friday

    May 4, 2016; 5:23 PM ET

    The Eta Aquarids meteor shower peaks Friday morning. But, Aquarid meteors will be visible each of the next several nights. This shower favors the Southern Hemisphere. But, the U.S. and Europe can still expect 10-30 meteors per hour early Friday morning.

  • Lyrid meteor shower battles full moon predawn Friday

    April 21, 2016; 11:45 AM ET

    The first major meteor shower in three months peaks predawn Friday. It will be visible across the Northern Hemisphere. The full moon will wash out some meteors. But, check out some tips of how to deal with the moon and see a few meteors Friday.

  • Keep an Eye to the Sky this Weekend

    April 15, 2016; 4:00 PM ET

    There is a lot to see in the night sky over the next few nights. The ISS makes a pass right over the Northeast U.S. Saturday night. Everyone will be able to see the conjunction of the moon and Jupiter Sunday night. The first major meteor shower in months, the Lyrids, peaks next week.

About This Blog

Astronomy Blog
The astronomy blog, by Dave Samuhel, discusses stargazing, including how weather will affect viewing conditions of astronomical phenomenon.