Monday, December 9, 2013

RADAR echoes of a dead comet...

via NASA Meteor Watch

The Andromedid meteor shower produced spectacular meteor storms in 1872 and 1885, caused by the breakup of the parent comet, 3D/Biela, in late 1842/early 1843. Why it broke apart is still a bit of a mystery, as the comet was well away from the Sun (out near Jupiter) at the time of its disintegration. One astronomer has suggested that Biela ran into the Leonid meteor stream, which disrupted its nucleus; however, it is much more likely that Jupiter's massive gravity was the culprit.

Since then, the Andromedid meteor shower has faded to a almost insignificant remnant of its former self. But recently, in 2011, and now in 2013, the CMOR meteor radar in Canada has been detecting outbursts of small meteors originating from a radiant in Cassiopeia (blue circle on the image). Even though some researchers consider this a separate shower (the December Phi Cassiopeids), there is no doubt that these are fragments of Biela ejected before it broke apart. Though very small and slow moving for meteors (only 42,500 mph), a rare few may be visible as faint streaks of light in a dark sky. The outburst is going on now, so we encourage observers to go out tonight if they can.

And just think - that faint streak of light is a fragment from a now dead comet, finally reaching Earth after a journey of 400 years.

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