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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

How the duck got its neck: Rapid temperature changes from self-shadowing may explain 67P's unusual activity and shape

Posted by Emily Lakdawalla on 2015/09/11 11:04 CDT | 5 comments

When Rosetta approached comet Churyumov-Gerasimenko last summer, both its shape and its activity were surprising. It looked like two comets welded together at a skinny neck. A new paper explains how the neck may be steepening itself.

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Dawn Ceres image bonanza: Grab your 3D glasses!

Posted by Emily Lakdawalla on 2015/09/09 08:04 CDT | 4 comments

For months, Dawn has been steadily, methodically sharing dozens of images of brand-new sights of a previously unexplored icy world. For the last couple of days I've been making up for lost time, completely buried in the Dawn Ceres images, and I have some maps and 3D anaglyphs to share with you.

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Aluminum Shapemodel of Comet 67P

Posted by Mattias Malmer on 2015/09/04 07:55 CDT | 4 comments

Mattias Malmer describes his MacGyver-esque process in creating a homemade aluminum version of 67P/Churyumov–Gerasimenko.

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Asteroids, Comets, and the Threat

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.

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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.

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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.

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