Stunningly bright fireballs created by meteors from Comet Hartley 2 have amazed skywatchers across the United States lucky enough to spot them.
The peanut-shaped comet, which was visited by a NASA spacecraft yesterday (Nov. 4), made a close pass by Earth on Oct. 20 and apparently created a new meteor shower of dust this week.
"I saw a bright white ball and tail, arcing towards the ocean," said skywatcher Helga Cabral of Seascape, Calif., who spotted a fireball at 9 p.m. local time last night (Nov. 3). "It was quite beautiful and it looked like it was headed out to sea and so picture-perfect it could have been a movie!"
Cabral's observations and those of other skywatchers were reported this week by the Minor Planet Center at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. They come after two fireballs, also likely from Hartley 2, were observed on Oct. 16. [Photos of the Oct. 16 fireballs]
The fireballs are caused by meteors that burn up in Earth's atmosphere before any bits can reach the ground.
Comet Hartley 2 up close
A meteor is an object that flares up in Earth's atmosphere. If a piece reaches the ground, it is called a meteorite. Before they encounter Earth's atmosphere, these objects are known as meteoroids.
Comet Hartley 2 is a periodic comet that completes one trip around the sun every 6 1/2 years. The comet is small and was discovered in 1986 by Australian astronomer Malcolm Hartley.
Earlier today, NASA's Deep Impact spacecraft zipped within 435 miles (700 kilometers) of Hartley 2 - the fifth up-close comet flyby ever ? and has beamed back stunning photos of the icy wanderer. It was the second comet flyby by the Deep Impact spacecraft, which visited Comet Tempel 1 in 2005.
Unlikely meteor show
Last week, NASA meteor experts predicted that the chances of seeing any meteors from Comet Hartley 2 would be slim, but said that if they were visible, the best time to see them would be this week. At the time, Comet Hartley was within about 12 million miles (19.3 million km) of Earth, officials with the Center for Astrophysics said.
And apparently, Comet Hartley 2 did not disappoint. [Photo of Comet Hartley 2]
"I was in the Revere area about 7:15 last night, driving north on Route 1, when a brilliant object with a tail passed in front of me ? very similar in appearance to a shooting star, but it appeared much lower to the Earth than a typical shooting star would be," said skywatcher Teresa Witham, who spotted the fireball late Tuesday from just north of Boston. "If it weren?t for the fact that I had my daughter with me, I'd begin to believe I?d imagined it."
Any meteors from Comet Hartley 2 would appear to emanate from a point in the sky near the bright star Procyon in the constellation Canis Minor, near Orion the Hunter, which is high overhead in the early hours before dawn.
Comets are well-known sources of meteor showers because they can sometimes leave trails of debris streams near Earth's orbital path. When Earth passes through these streams, the material can burn up in the atmosphere to create meteor fireballs.
For example, the Leonid meteor shower ? which arrives each year in mid-November ? is caused by the remains of the comet Tempel-Tuttle. Two other meteor showers, the Aquarids of May and October's Orionid shower, are caused by the famed Halley's Comet.
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