Fire in the Sky
Sat, 30 Jul 2011 10:40 UTC
Astronomy Magazine / SETI Institute
Fri, 29 Jul 2011 16:27 UTC
The Central Bureau issued a telegram July 10 for Astronomical Telegrams of the International Astronomical Union (IAU) announcing that a stream of dust from a potentially dangerous comet impacted Earth for a few hours last February 4.
"This particular shower happens only once or twice every 60 years," said Peter Jenniskens from the Search for Extraterrestrial Intelligence (SETI) Institute, Mountain View, California. "The stream of dust is always there, but quite invisible just outside of Earth's orbit. Only when the planets steer the dust in Earth's path do we get to know it is there."
Since last October, the SETI Institute has teamed up with Fremont Peak Observatory in San Juan Batista, California, and UCO/Lick Observatory just east of San Jose, California, in monitoring the night sky with low-light video cameras in an effort to map the meteor showers in the sky over the San Francisco Bay Area. They triangulate the meteor trajectories and determine their orbits in space.
Below is a list of some astronomical events for the remainder of 2011. If you are a star gazing novice, SkyMaps.com offers a monthly "sky map" that can help you know where to look.
July 28, 29 - Southern Delta Aquarids Meteor Shower. The Delta Aquarids can produce about 20 meteors per hour at their peak. The shower usually peaks on July 28 & 29, but some meteors can also be seen from July 18 - August 18. The radiant point for this shower will be in the constellation Aquarius. This year the thin, crescent moon will be hanging around for the show, but it shouldn't cause too many problems. Best viewing is usually to the east after midnight from a dark location.
July 30 - New Moon. The moon will be directly between the Earth and the Sun and will not be visible from Earth. This phase occurs at 18:40 UTC.
The video, taken by the Solar Dynamics Observatory, shows a plasma eruption that swirls up like a tornado to a dizzying height of up to 93,206 miles (150,000 kilometers) above the solar surface.
"Its height is roughly between 10 to 12 Earths," solar astrophysicist C. Alex Young of NASA's Goddard Space Flight Center in Greenbelt, Md., told SPACE.com.
The solar twister occurred on July 12 when an eruption of magnetic plasma, called a prominence, spiraled up from the sun in a graceful whirlwind, then split into four separate strands that twisted into a knot before fading away. The entire event lasted just a few hours.
Young said the ethereal twister look of the prominence was largely a matter of perspective. The Solar Dynamic Observatory was seeing the eruption from an angle that caught the prominence's rise up from the solar surface.
San Francisco Chronicle
Wed, 27 Jul 2011 23:38 UTC
A stream of dusty fragments from a comet born in the outermost reaches of the solar system has hit the Earth on a path that leads astronomers to conclude the comet itself could be "potentially hazardous" if it crashes into the planet.
The comet's location is unknown, making it difficult to say when it will approach Earth, but "the orbits of the dust trail tells us that the comet is on a path that could eventually hit us," said Peter Jenniskens, an astronomer at the SETI Institute and the NASA Ames Research Center in Mountain View.
"It's very unlikely," he conceded Wednesday. "Such impacts are extremely rare in Earth's history."
The trail of dust grains, known as meteoroids, were shed by the comet long ago as it passed the sun and Earth on a long orbit that could have taken thousands of years to complete, Jenniskens said.
The comet was born billions of years ago and trillions of miles away in the cold comet nursery called the Oort Cloud, and streams of the comet's dusty progeny have returned to Earth once or twice every 60 years or so when their orbits come under the influence of Saturn and Jupiter, Jenniskens said.
Wed, 27 Jul 2011 16:30 UTC
A surprise meteor shower spotted by skywatchers in February was likely caused by cosmic "bread crumbs" left over from an undiscovered comet that could potentially pose a threat to Earth, astronomers announced today (July 27).
The tiny meteoroids that streaked through Earth's atmosphere for a few hours on Feb. 4 represent a previously unknown meteor shower, researchers said. The "shooting stars" arrived from the direction of the star Eta Draconis, so the shower is called the February Eta Draconids, or FEDs for short.
The bits of space rock appear to have been shed by a long-period comet. Long-period comets whiz by the sun only rarely, so it's tough to predict when they last came through our neck of the woods - and when they'll come back, researchers said.
That uncertainty is cause for some concern in this case, they added.
"If the meteoroids can hit us, so can the comet," said FEDs discoverer Peter Jenniskens, of the SETI (Search for Extraterrestrial Intelligence) Institute and NASA's Ames Research Center. "We don't know whether the comet has already passed us by or is still on approach."
Still, Jenniskens stressed that the chances of such a collision are extremely remote.
Mon, 25 Jul 2011 11:22 UTC