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12

It depends. There are collisions amongst asteroids that have been caught on film that had no effect on us whatsoever. In your scenario, they would have to have a resultant vector towards us in order to cause any problems. Then there is the question of how many resultant particles are big enough to cause any problems (that is, big enough to get through our ...


11

There are several points of evidence that the Oort Cloud exists, though it is indeed still a hypothesis and lacks direct observation. The first is indirectly observational, as proposed by Ernst Öpik back in 1932 as the source of long-period comets. This was revised by Jan Oort in 1950. All you need to determine an orbit is three observations of the ...


8

At the risk of being snarky (each definition is from wikipedia)... Comet - A comet is an icy small Solar System body that, when close enough to the Sun, displays a visible coma (a thin, fuzzy, temporary atmosphere) and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet. ...


8

I'm not a professional, but I'll try to answer anyway. Meteor showers occur when the Earth passes through the orbit of a comet (or, in at least one case, an asteroid). Over time, the debris spreads over the entire orbit of the comet. A shower can last for several days, which is an indication of how wide the debris stream is. Assuming a duration of 1 day, ...


6

An estimate of impacts from long-period comets is available at this NASA JPL site. They appear to be randomly distributed . Given detection at about 5 AU, we'd only have a year of warning for potential impactors. Their mean impact velocity is in the order of 52 km/s with an impact probability crossing Earth's orbit of 2.2 - 2.5x${10^{ - 9}}$ per perihelion ...


6

It is unlikely that comets are a feature unique to our Solar System. Since comets are simply remnants of star and planetary formation, then anywhere stars and planets have formed would be fertile ground to expect comets. Their individual masses are relatively very small compared to discovered planets. For example, Halley's Comet has a mass of roughly ...


4

There are a few phenomena that can cause sound to be heard from a meteorite. Here it says that sonic booms as well as shock waves due to larger fragments breaking up can reach and be detected by the human ear. There is also the so-called electrophonic effect. Given that most meteorites burn up at ~100km altitude, sonic boom and shock waves would take $ t ...


3

It seems Comet Elenin broke up on this pass through the inner Solar System, and that's why it is not visible. http://www.msnbc.msn.com/id/45050612/ns/technology_and_science-space/t/comet-elenin-dead-along-doomsday-predictions/


1

I would try here, generate an ephemeris for the object of interest (some objects may already be in the database.) HORIZONS Web-Interface This tool provides a web-based limited interface to JPL's HORIZONS system which can be used to generate ephemerides for solar-system bodies. Full access to HORIZONS features is available via the primary telnet interface. ...


1

I'd heard about a really detailed simulation of an India-Pakistan nuclear war, and found an oblique reference to it on Wikipedia. The money quote is "Five million tons of soot would be released, which would produce a cooling of several degrees over large areas of North America and Eurasia, including most of the grain-growing regions. The cooling would last ...



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