A view of a shooting star (Draconid) and northern lights near Skekarsbo at the Farneb of jardens national park, 150 km (93 miles) north of Stockholm October 8, 2011. Source: REUTERS
The Draconid meteors are caused when Earth collides with bits of debris shed by periodic comet 21P/Giacobini-Zinner (and that’s why this shower used to be called the Giacobinids). The comet has a 6½-year-long orbit that periodically carries it near Jupiter. Ordinarily, celestial dynamicists would expect the planet’s powerful gravity to scatter anything in its vicinity into varying and unpredictable orbits. But they believe that a stream of particles, ejected in 1900, is still largely intact. The meteors appear to travel from a point near the head of Draco the Dragon, a constellation visible all year for most people with a view of the northern sky, as Earth sideswiped that river of rubble on Saturday.
The comet orbits the sun once every 6.6 years, leaving tendrils of dust in its wake. This year the Earth encountered three or four of these tendrils. Usually the Draconid meteor shower delivers no more than 10 to 20 meteors per hour at its peak. However, meteor specialists estimated that this year’s Draconid rates could top 600 per hour — that’s 10 per minute — under ideal viewing conditions.
This year’s dramatic peak only lasted a few hours as it was poorly timed (4 p.m. EDT, 1 p.m. PDT) for North Americans. European observers definitely had the best view, despite interference from a waxing gibbous Moon. Still, it appeared that the 2011 Draconids were quite an impressive show, if short-lived.
The unusually intense shower poses an increased risk to satellites, noted Bill Cooke, who heads NASA’s Meteoroid Environment Office at the Marshall Spaceflight Center in Huntsville, Ala. Some satellites can ride out the storm, while others – those with cameras or telescopes – likely will be turned so the delicate optics face away from the oncoming dust grains.
As for the International Space Station, he adds, it’s sufficiently armored to withstand hits from the Draconids. But, he adds, don’t look for any astronauts to conduct spacewalks during the shower.
“Most years, we pass through gaps between filaments, maybe just grazing one or two as we go by,” Cooke said in a statement beforehand. “Occasionally, though, we hit one nearly head on – and the fireworks begin.”
Draconid impacts on the Moon?
White dots denote where meteoroids from comet 21P/Giacobini-Zinner can impact the Moon on October 8th. In the hours after the shower, telescopic observers watched for lunar impacts in the sliver of darkness on the Moon near the north pole. Credit: P. Gural / J. Vaubaillon
Posted by: Soderman/NLSI Staff