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SpaceWeather.com -- News and information about meteor showers, solar flares, auroras, and near-Earth asteroids
SPACE WEATHER
Current conditions
Solar wind
speed: 341.2 km/sec
density: 2.7 protons/cm3
explanation | more data
Updated: Today at 2246 UT
X-ray Solar Flares
6-hr max: A0
2245 UT Dec20
24-hr: A0
0050 UT Dec20
explanation | more data
Updated: Today at: 2245 UT
Daily Sun: 20 Dec 08
The sun is blank--no sunspots. Credit: SOHO/MDI
Sunspot number: 0
What is the sunspot number?
Updated 18 Dec. 2008
Far side of the Sun:
This holographic image reveals no sunspots on the far side of the sun. Image credit: SOHO/MDI
Planetary K-index
Now: Kp= 0 quiet
24-hr max: Kp= 1
quiet
explanation | more data
Current Auroral Oval:
Switch to: Europe, USA, New Zealand, Antarctica
Credit: NOAA/POES
What is the auroral oval?
Interplanetary Mag. Field
Btotal: 5.7 nT
Bz: 0.3 nT south
explanation | more data
Updated: Today at 2247 UT
Coronal Holes:
A solar wind stream flowing from the indicated coronal hole should reach Earth on or about Dec. 22nd. Credit: SOHO Extreme UV Telescope
SPACE WEATHER
NOAA Forecasts
Updated at: 2008 Dec 20 2201 UTC
FLARE
0-24 hr
24-48 hr
CLASS M
01 %
01 %
CLASS X
01 %
01 %
Geomagnetic Storms:
Probabilities for significant disturbances in Earth's magnetic field are given for three activity levels: active, minor storm, severe storm
Updated at: 2008 Dec 20 2201 UTC
Mid-latitudes
0-24 hr
24-48 hr
ACTIVE
10 %
20 %
MINOR
01 %
05 %
SEVERE
01 %
01 %
High latitudes
0-24 hr
24-48 hr
ACTIVE
10 %
20 %
MINOR
01 %
05 %
SEVERE
01 %
01 %
What's up in Space
December 20, 2008

For less than the cost of a night at the movies, you can give someone the heavens for Christmas. Now available: gift subscriptions to Spaceweather PHONE.

 

RADIO METEORS: The Ursid meteor shower caused by Comet 8P/Tuttle peaks this year on Dec. 22nd. About a dozen meteors per hour will fly out of the Little Dipper (Ursa Minor) as Earth passes through the comet's debris stream. Watching these northern meteors can be a chilling experience, so why not stay inside and listen to them instead? Spaceweather.com is broadcasting live audio from the Air Force Space Surveillance Radar in Texas. When a meteor passes over the radar--"ping"--there is an echo. Give it a try; feedback is welcomed.

NACREOUS CLOUDS: For the second time in a week, nacreous clouds have made an appearance over Scandinavia. On Dec. 17th they were sighted over Trondheim, Norway. Yesterday, the clouds came to Kittila, Finland:


Photo details: Nikon D3, 1/160 sec, ISO 200

"These were our first nacreous clouds of the season," says photographer Sauli Koski. "I could watch them all day!"

Nacreous clouds are located in the stratosphere some 9 to 16 miles high. Their iridescent "mother of pearl" colors come from sunlight striking tiny ice crystals inside the clouds. Very low temperatures near -85o C are required to form the crystals, which is why nacreous clouds are seen mainly during winter over places like Alaska, Iceland and Scandinavia.

These clouds are supposed to be rare, yet earlier this year Scandinavians witnessed a veritable "nacreous storm." For more than a week in January 2008, hardly a night went by without someone spotting mother-of-pearl colors in the sky. No one knows what caused the storm or if it could happen again. One thing is sure: northern sky watchers should be alert for more. The best time to look is during the twilight hours before dawn or after sunset.

2008 Nacreous Cloud Photo Gallery
[Nacreous cloud tutorial] [Night-sky cameras]

SATURN'S RINGS: You might never see Saturn's rings this skinny again. Since 2008 began, the rings have been tilting toward Earth and now they are nearly edge-on with an opening angle of only 0.8o. A composite image submitted by Efrain Morales Rivera of Aguadilla, Puerto Rico, shows how the geometry has changed:

As Saturn goes around the sun, it periodically turns its rings edge-on to Earth—once every 14-to-15 years. That's what is happening now. Earth is approaching Saturn's "ring plane," a vantage that transforms the normally wide and bright rings into a dark line bisecting Saturn's two hemispheres.

The rings will completely disappear on Sept. 4, 2009, when Earth crosses through the ring plane. Unfortunately, no one will be able to see it because Saturn will be so close to the Sun. The next ring plane crossing in plain view of Earth won't come until the year 2038.

Until then, the skinniest you're likely to see Saturn's rings is now. Saturn is easy to find in the constellation Leo just before dawn. Point your backyard telescope and behold the edge: sky map.


Dec. 2008 Aurora Gallery
[Previous Decembers: 2007, 2006, 2005, 2001, 2000]

       
Near-Earth Asteroids
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 20, 2008 there were 1010 potentially hazardous asteroids.
Dec. 2008 Earth-asteroid encounters:
Asteroid
Date(UT)
Miss Distance
Mag.
Size
2008 WY94
Dec. 5
3.2 LD
19
35 m
2008 WG14
Dec. 5
4.8 LD
17
49 m
2008 XK
Dec. 6
1.7 LD
17
15 m
2008 XC1
Dec. 12
4.3 LD
16
102 m
2008 XB2
Dec. 13
5.8 LD
18
47 m
2006 VB14
Dec. 14
36 LD
15
795 m
2008 EV5
Dec. 23
8.4 LD
13
435 m
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.
Essential Links
NOAA Space Weather Prediction Center
  The official U.S. government space weather bureau
Atmospheric Optics
  The first place to look for information about sundogs, pillars, rainbows and related phenomena.
Solar and Heliospheric Observatory
  Realtime and archival images of the Sun from SOHO.
STEREO
  3D views of the sun from NASA's Solar and Terrestrial Relations Observatory
Daily Sunspot Summaries
  from the NOAA Space Environment Center
Current Solar Images
  from the National Solar Data Analysis Center
Science Central
  a one-stop hub for all things scientific
  more links...
   
©2008, SpaceWeather.com -- This site is penned daily by Dr. Tony Phillips.
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