BAY AREA FIREBALL: Last night, Oct. 17th, many people near San Francisco saw a slow-moving fireball exploding in the sky around 07:45 pm PDT. Witnesses report bright flashes of light and sonic booms that shook houses. Using a wide-field camera, Wes Jones caught the meteor disappearing behind the trees in the city of Belmont:
“We don’t know yet if the end point [of the meteor’s flight] was over land or water,” says meteor expert Peter Jenniskens of the NASA Ames Research Center. Jenniskens operates a network of Cameras for All-sky Meteor Surveillance (CAMS) near the Bay Area. “Data from the CAMS system should give us an answer [about landfall]. We’re analyzing the data now.” Stay tuned.
Note: Although Earth is nearing a stream of debris from Halley’s Comet, source of the Orionid meteor shower, this fireball was probably not an Orionid. The timing and direction of the meteor do not seem to match the Orionids.
Oct. 12, 2012: Usually, waking up before sunrise is a good way to get a head start on the day. On Oct. 21st, waking up early could stop you in your tracks.
Blame Halley’s Comet. Every year in mid-to-late October, Earth passes through a stream of dusty debris from Comet Halley, and the pre-dawn sky lights up with a pretty display of shooting stars.
“We expect to see about 25 meteors per hour when the shower peaks on Sunday morning, Oct 21st,” says Bill Cooke, the head of NASA’s Meteoroid Environment Office. “With no Moon to spoil the show, observing conditions should be ideal.”
A new ScienceCast video explores the Orionid meteor shower. Play it
Because these meteors streak out of the constellation Orion, astronomers call them “Orionids.”
“The Orionid meteor shower isn’t the strongest, but it is one of the most beautiful showers of the year,” notes Cooke.
The reason is its setting: The shower is framed by some of the brightest stars and planets in the heavens. Constellations such as Taurus, Gemini and Orion provide a glittering backdrop for the display. But that’s not all. This year, Venus and Jupiter have moved into position with Sirius, the Dog Star, to form a bright triangle in the eastern pre-dawn sky. On the morning of Oct 21st, blazing pieces of Halley’s Comet will cut straight through the heart of this celestial triad.
To see the show, Cooke suggests going outside one to two hours before sunrise when the sky is dark and the constellation Orion is high overhead. Lie down on a blanket with a broad view of the heavens. Although Orionids emerge from a small area near the shoulder of Orion, they will spray across the entire sky.
“Be prepared for speed,” he adds. “Meteoroids from Halley’s Comet strike Earth’s atmosphere traveling 148,000 mph. Only the November Leonids are faster.”
Speed is important because fast meteors have a tendency to explode. Occasionally, Orionid fireballs will leave incandescent streams of debris in their wake that linger for minutes. Such filaments of meteor smoke twisted by upper atmospheric winds into convoluted shapes can be even prettier than the meteors themselves.
“It really is a wonderful morning to be awake,” says Cooke. “Just don’t plan on going anywhere in a hurry.”
October 21 and 22, before dawn. Orionids
Although the moon doesn’t rise till after midnight, the Orionids usually wait until the wee morning hours to pick up steam. And there will be a rather large waning crescent moon in the sky during this year’s Orionid meteor shower. Despite the moonlight, meteor enthusiasts may want to give the Orionids a try. On a dark, moonless night, the Orionids exhibit a maximum of about 15 meteors per hour. These fast-moving meteors occasionally leave persistent trains and bright fireballs. If you trace these meteors backward, they seem to come from the Club of the famous constellation Orion the Hunter. You might know Orion’s bright, ruddy star Betelgeuse. The radiant is north of Betelgeuse. The Orionids have a broad and irregular peak that isn’t easy to predict. More meteors tend to fly after midnight, and the Orionids are typically at their best in the wee hours before dawn. The best viewing for the Orionids in 2011 will probably be before dawn on October 21 or 22, though the waning crescent moon will interfere with this year’s Orionid display. But check ‘em out anyway. As we learned during the Draconids shower earlier this month … even one meteor streaking along in bright moonlight can be breathtaking.