Asteroids and Comets

All the Little Things in the Solar System, and the Things They Can Do to Earth

Is there an asteroid or comet out there that poses a risk to life on Earth? The answer is certainly "yes," but we don't yet know where the next major impactor will come from or when it will crash. The best way to reduce this uncertainty is to search the skies for these crumbs of the solar system. The Planetary Society has a long history of supporting amateur and underfunded professional astronomers in their efforts to discover and track potentially hazardous near-Earth objects. This is useful not only for planetary defense, but also for learning about the solar system's origin and evolution.

A fortuitous byproduct of our increasing ability to detect fainter objects is that, for the first time, we now stand a chance of discovering smaller, five- to ten-meter-sized rocks while they are still in space before they burn up in our atmosphere and scatter meteorites along the ground. We are now beginning to link meteorites that we can study in our labs with the data on orbits and compositions that we amass with astronomical observations. Every meteorite, every tiny asteroid has a story, and we can combine these stories together to answer fundamental questions about how the solar system formed and evolved. What were the ingredients that made Earth and the other planets? How are those constituents different now? How have asteroid and comet impacts shaped the origin and evolution of life on Earth (and, potentially, on other planets)? Can asteroids serve as stepping-stones for human travel to farther destinations?

Blogs About Asteroids, Comets, and the Impact Threat

Oblique view of the lunar limb from Apollo 10

LPSC 2013: The Smaller They Are, The Better They Shake

Posted by Emily Lakdawalla on 2013/03/25 08:04 CDT | 1 comments

Really cool movies from Jim Richardson propose to explain how the same physics of impact cratering can produce such differently-appearing surfaces as those of the Moon, large asteroids like Eros, and teeny ones like Itokawa.

Planetary Society Weekly Hangout: the Giant ALMA Observatory, and Asteroid Tracking

Posted by Bruce Betts on 2013/03/20 01:31 CDT

Bruce Betts, Mat Kaplan, and asteroid tracker Robert Holmes on the Planetary Society Weekly Google Hangout. Mat discussed and showed pictures from his trip to the giant ALMA observatory and we'll be joined by asteroid tracker extraordinaire, Robert Holmes.

Comet PANSTARRS, Earth, and a coronal mass ejection as seen from STEREO-B

Comet PANSTARRS from the other side of the Sun!

Posted by Karl Battams on 2013/03/14 05:21 CDT | 8 comments

Comet PANSTARRS is delighting northern hemisphere viewers right now. But it's also big, bright, and beautiful to the STEREO spacecraft.

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Eros' northern hemisphere as seen by the NEAR spacecraft on February 29, 2000. The view is a mosaic of six images.

Asteroids and Comets Visited by Spacecraft

A comparison of all the asteroids and comets ever visited by spacecraft, up to date as of November 10 (when Deep Impact flew past Hartley 2). Vesta is not included.

During the first few hundred million years after oceans appeared on the young Earth, life may have repeatedly begun only to be erased in planetwide sterilization events as very large planetoids were colliding with the larger worlds.

Sizing Up the Threat from Near-Earth Objects (NEOs)

Scientifically, it is useful to divide the impact hazard into two types of events: those with local consequences and those with global consequences. Global events, while much less likely, actually pose a greater risk.

The Torino Scale

The Torino scale is a color-coded advisory system that enables near-Earth object (NEO) researchers to place objects within a potential threat range from zero -- where there is virtually no chance of collision, to 10 -- where global catastrophe is certain.