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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

Dawn Journal: Staying at Ceres

Posted by Marc Rayman on 2016/07/30 01:19 CDT | 9 comments

The official end of Dawn's prime mission was June 30, but the valiant adventurer began its "extended mission" of performing more Ceres observations without missing a beat.

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Rosetta end-of-mission plans: Landing site, time selected

Posted by Emily Lakdawalla on 2016/07/26 03:13 CDT | 2 comments

ESA's comet-chasing Rosetta spacecraft is nearing the end of its mission. Last week, ESA announced when and where Rosetta is going to touch down. And tomorrow, it will forever shut down the radio system intended for communicating with the silent Philae lander.

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Dawn Journal: In the Details

Posted by Marc Rayman on 2016/06/08 06:33 CDT | 6 comments

Dawn is continuing to record the extraordinary sights on dwarf planet Ceres. The experienced explorer is now closer to the alien world than the International Space Station is to Earth.

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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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