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
When comet ISON passed through perihelion last week, solar observing spacecraft had a ringside view. Here are several animations of ISON's perilous passage from the SOHO and two STEREO spacecraft.
Two Hangouts bookended comet ISON's perihelion, hosted by Chuck Beuter of Comet Festival South Bend. On November 25, it was I and Ron Kaitchuck. On December 2, Alex Filippenko and I discussed what happened to the comet over Thanksgiving.
After impressing us yesterday, comet ISON faded dramatically overnight, and left us with a comet with no apparent nucleus in the SOHO/LASCO C2 images. As the comet plunged through the solar atmosphere, and failed to put on a show in the SDO images, we understandably concluded that ISON had succumbed to its passage and died a fiery death. Except it didn't. Well, maybe...
Asteroids, Comets, and the Threat
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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