As of 8-6-08 - There were 971 tracked asteroids 
See chart on that date
On October 3, 2008 , there were 986 potentially hazardous asteroids.
See chart on that date
On 10-12-08 - there are 990 potentially hazardous asteroids.
See chart on that date
One - the size of a car exploded over the Sudan on 10-07-08
On 10-29-08 -there are 993 potentially hazardous asteroids.
On 11-6-08 - there are 996 potentially hazardous asteroids.
On 11-24-08 -- there are 999 potentially hazardous asteroids.
On 12-2-08 - there are 1002 potentially hazardous asteroids.
On 12-12-08 - there are 1010 potentially hazardous asteroids.

SPACE WEATHER 2009
 

Dan Linek of North Bay Shore, New York, was one of the eye witnesses. Combining his own observations with those of others, he created a hand-drawn map of sightings and the probable location of the fireball when it exploded:

CALIFORNIA FIREBALL: A remarkable fireball blazed across Califonia on Dec. 27th around 1:50 am PST. Its brilliant blue-green light caught the attention of onlookers (some inside their homes) all the way from San Francisco Bay in the north to the Los Angeles metropolitan area in the south--a range of more than 340 miles. According to one account, the object exploded with a thunderous boom, producing a spray of golden-colored fragments

"It was as if someone had set off a rescue flare that instantly bathed the countryside in whitish blue-green light," reports Grant Bentley of Bishop, CA. "At one point, the path of the meteor went behind a cirrus-stratus cloud that it backlit in snowy green light. After a brilliant show of less than three seconds, it was gone without a trace. This was easily the most massive object I have ever seen burning up as it entered the Earth's atmosphere."

A solar wind stream flowing from the indicated coronal hole
should arrive on Dec. 30th or 31st.
Credit: SOHO Extreme UV Telescope
 

LAST AURORAS OF 2008: They're coming, the last auroras of 2008. The source of the display is a coronal hole photographed earlier today by Japan's Hinode spacecraft:

Although 2008 has been a year of remarkably low solar activity, polar sky watchers nevertheless have enjoyed many good geomagnetic storms. Galleries: January, February, March, April, May, June, July, August September, October, November, December.
 

"Everyone should take a look before the rings begin to open up again at the end of the month," says Casquinha. A nice bonus: When the rings are thin, Saturn's moons become easier to see. "Note the small spot above the rings on the right; that's Rhea."

more images: from Masa Nakamura of Otawara, Tochigi, Japan; from Koshu Endo of Tokyo Japan (note: Endo's video shows an Earth-orbiting satellite zipping by Saturn)

CHRISTMAS PROMINENCE: So, you received a solar telescope for Christmas? Perfect timing. A plume of hot gas is spewing over the northeastern limb of the sun, beckoning for attention. Take a look!

photos: from S. Billings et al of South Portland, Maine; from Mike Borman of Evansville, Indiana; from Francisco A. Rodriguez of Gran Canaria, Canary Islands; from James Screech of Bedford, England; from Peter Desypris of Athens, Greece; from Stephen Ames of Hodgenville, Kentucky;

NASA's Stereo-B spacecraft is stationed over the sun's eastern limb, but it was not taking pictures at the probable time of the eruption, so details of the blast are unknown. The CME could herald an active region (e.g., a sunspot or perhaps an unstable magnetic filament) turning to face Earth in the days ahead. Stay tuned for updates.

Dec. 16, 2008: NASA's five THEMIS spacecraft have discovered a breach in Earth's magnetic field ten times larger than anything previously thought to exist. Solar wind can flow in through the opening to "load up" the magnetosphere for powerful geomagnetic storms. But the breach itself is not the biggest surprise. Researchers are even more amazed at the strange and unexpected way it forms, overturning long-held ideas of space physics.

"At first I didn't believe it," says THEMIS project scientist David Sibeck of the Goddard Space Flight Center. "This finding fundamentally alters our understanding of the solar wind-magnetosphere interaction."

The magnetosphere is a bubble of magnetism that surrounds Earth and protects us from solar wind. Exploring the bubble is a key goal of the THEMIS mission, launched in February 2007. The big discovery came on June 3, 2007, when the five probes serendipitously flew through the breach just as it was opening. Onboard sensors recorded a torrent of solar wind particles streaming into the magnetosphere, signaling an event of unexpected size and importance. One of the THEMIS probes exploring the space around Earth, an artist's concept. [more]

"The opening was huge—four times wider than Earth itself," says Wenhui Li, a space physicist at the University of New Hampshire who has been analyzing the data. Li's colleague Jimmy Raeder, also of New Hampshire, says "10²⁷ particles per second were flowing into the magnetosphere—that's a 1 followed by 27 zeros. This kind of influx is an order of magnitude greater than what we thought was possible."

The event began with little warning when a gentle gust of solar wind delivered a bundle of magnetic fields from the Sun to Earth. Like an octopus wrapping its tentacles around a big clam, solar magnetic fields draped themselves around the magnetosphere and cracked it open. The cracking was accomplished by means of a process called "magnetic reconnection." High above Earth's poles, solar and terrestrial magnetic fields linked up (reconnected) to form conduits for solar wind. Conduits over the Arctic and Antarctic quickly expanded; within minutes they overlapped over Earth's equator to create the biggest magnetic breach ever recorded by Earth-orbiting spacecraft.

Above: A computer model of solar wind flowing around Earth's magnetic field on June 3, 2007. Background colors represent solar wind density; red is high density, blue is low. Solid black lines trace the outer boundaries of Earth's magnetic field. Note the layer of relatively dense material beneath the tips of the white arrows; that is solar wind entering Earth's magnetic field through the breach. Credit: Jimmy Raeder/UNH. [larger image]

The size of the breach took researchers by surprise. "We've seen things like this before," says Raeder, "but never on such a large scale. The entire day-side of the magnetosphere was open to the solar wind."

The circumstances were even more surprising. Space physicists have long believed that holes in Earth's magnetosphere open only in response to solar magnetic fields that point south. The great breach of June 2007, however, opened in response to a solar magnetic field that pointed north.

"To the lay person, this may sound like a quibble, but to a space physicist, it is almost seismic," says Sibeck. "When I tell my colleagues, most react with skepticism, as if I'm trying to convince them that the sun rises in the west."

"So, you can imagine our surprise when a northern IMF came along and shields went down instead," says Sibeck. "This completely overturns our understanding of things."

Northern IMF events don't actually trigger geomagnetic storms, notes Raeder, but they do set the stage for storms by loading the magnetosphere with plasma. A loaded magnetosphere is primed for auroras, power outages, and other disturbances that can result when, say, a CME (coronal mass ejection) hits.

The years ahead could be especially lively. Raeder explains: "We're entering Solar Cycle 24. For reasons not fully understood, CMEs in even-numbered solar cycles (like 24) tend to hit Earth with a leading edge that is magnetized north. Such a CME should open a breach and load the magnetosphere with plasma just before the storm gets underway. It's the perfect sequence for a really big event."

Sibeck agrees. "This could result in stronger geomagnetic storms than we have seen in many years."