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MOSTLY QUIET, SLIGHT CHANCE OF STORMS: NOAA forecasters have downgraded the odds of geomagnetic storms around the poles today to 15%. Bright auroras are unlikely as Earth's magnetic field remains quiet. Aurora alerts: text, voice.
BIG ASTEROID FLYBY: Large near-Earth asteroid 4179 Toutatis is flying past Earth this week. At closest approach on Dec. 12th, it will be 7 million km away, or 18 times farther than the Moon. Astronomers are taking advantage of the flyby to learn more about the asteroid's orbit, shape, and topography. Here are a few shadowy images of the asteroid illuminated by NASA's Goldstone radar in the Mojave desert:
Measuring 5 km in length, Toutatis is one of the largest known potentially hazardous asteroids (PHAs) and its orbit is inclined less than half-a-degree from Earth's. No other kilometer-sized PHA moves around the Sun in an orbit so nearly coplanar with our own. This makes it an important target for asteroid studies.
Fortunately, there is no danger of a collision with Toutatis for hundreds of years. Radar observations should improve researchers' ability to predict the asteroid's trajectory even farther into the future. Goldstone will pinging Toutatis from now until Dec. 22nd. Stay tuned for daily updates.
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ANOTHER ERUPTION MISSES EARTH: Magnetic fields around departing sunspot AR1621 became unstable and erupted during the late hours of Dec. 7th, hurling a bulb of plasma off the sun's western limb. NASA's Solar Dynamics Observatory recorded its departure:
Earth was not in the line of fire. No auroras or other space weather effects will be felt as a result of the blast.
Overall, solar activity is very low. The face of the sun is nearly blank (few sunspots) and NOAA forecasters estimate a slight 1% chance of strong flares during the next 24 hours.
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[previous years: 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2011]
Potentially Hazardous Asteroids (
PHAs) are space rocks larger than approximately 100m that can come closer to Earth than 0.05 AU. None of the known PHAs is on a collision course with our planet, although astronomers are finding
new ones all the time.
On December 8, 2012 there were 1354 potentially hazardous asteroids.
Notes: LD means "Lunar Distance." 1 LD = 384,401 km, the distance between Earth and the Moon. 1 LD also equals 0.00256 AU. MAG is the visual magnitude of the asteroid on the date of closest approach. | The official U.S. government space weather bureau |
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