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<<back forward>> -- News and information about meteor showers, solar flares, auroras, and near-Earth asteroids
Current conditions
Solar wind
speed: 361.4 km/sec
density: 4.8 protons/cm3
explanation | more data
Updated: Today at 2345 UT
X-ray Solar Flares
6-hr max: B2
2335 UT Dec21
24-hr: C2
0715 UT Dec21
explanation | more data
Updated: Today at: 2340 UT
Daily Sun: 20 Dec. 09
All three of these sunspots are members of new Solar Cycle 24. The image is purple because was taken through a violet Calcium-K filter sensitive to the light emitted by magnetic froth around sunspots. Image credit: Stefano Sello of Pisa, Italy
Sunspot number: 42
What is the sunspot number?
Updated 20 Dec 2009

Spotless Days
Current Stretch: 0 days
2009 total: 259 days (73%)
Since 2004: 770 days
Typical Solar Min: 485 days
explanation | more info
Updated 20 Dec 2009

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= 2 quiet
24-hr max: Kp= 2
explanation | more data
Current Auroral Oval:
Switch to: Europe, USA, New Zealand, Antarctica
Interplanetary Mag. Field
Btotal: 4.2 nT
Bz: 1.1 nT north
explanation | more data
Updated: Today at 2345 UT
Coronal Holes:
A solar wind stream flowing from the indicated coronal hole could reach Earth on or about Dec. 22nd. Credit: SOHO Extreme UV Telescope
NOAA Forecasts
Updated at: 2009 Dec 21 2201 UTC
0-24 hr
24-48 hr
10 %
05 %
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: 2009 Dec 21 2201 UTC
0-24 hr
24-48 hr
05 %
05 %
01 %
01 %
01 %
01 %
High latitudes
0-24 hr
24-48 hr
05 %
05 %
01 %
01 %
01 %
01 %
What's up in Space
December 21, 2009

ASTRONOMY ALERTS: Looking for a unique and affordable gift? Give the heavens for Christmas at Spaceweather PHONE.


THE SEASONS ARE CHANGING: Today at 12:47 pm EST (1747 UT), the sun dipped to its lowest celestial latitude of the year. The event, called "the December solstice," marks the beginning of winter in the northern hemisphere and summer in the southern hemisphere. Happy Solstice! Stonehenge Solstice Photos: #1, #2, #3, #4, #5

SUNSET SKY SHOW: When the sun sets tonight, go outside and look up. Jupiter and the crescent Moon will be shining side-by-side in the southwestern sky. Photographer Mahdi Zamani sends this photo from Tehran, Iran:

"Jupiter and the Moon were spectacular shining through the fronds of this Middle Eastern-style Christmas tree," says Zamani. "I took the picture using a Canon 50D set at ISO 650 for six seonds."

Advice to readers: Look before the sky fades all the way to black. A bright conjunction of worlds framed by twilight blue is an especially lovely sight. [sky map]

more images: from Rafael Schmall of Hungary, Somogy, Kaposfo; from Valentin Grigore of Targoviste, Romania; from Khosro JafariZadeh of Shushtar, Khuzestan, Iran; from Alex Conu of Bucharest, Romania; from Catalin M. Timosca of Mihai Viteazul, Romania; from Tomasz Adam of Staszów, Poland; from Mohamad Soltanolkottabi of Kashan, Iran

DON'T TRY THIS AT HOME: Looking at the sun through unfiltered optics can be very dangerous. This is especially true if you're a snowman:

"He might have to wait till dark to catch any stars--if he lasts that long," says photographer Jonathan Bingham of Killead, Northern Ireland.

Today's sun is a tempting target. For the first time in a year and a half, there are three spots on the sun at the same time. With the sun in the pits of the deepest solar minimum in a century, such an outbreak is remarkable. Readers with safely-filtered solar telescopes should take a look.

more photos: from Andreas Murner of Rosenheim, Bavaria, Germany; from Rogerio Marcon of Campinas - Brasil; from Pete Lawrence of Selsey, West Sussex, UK; from Adrian Guzman of San Jose, CA; from Fabio Mariuzza of Biauzzo, Italy; from Richard Best of Lewes, Sussex, England; from Javier Temprano of Santander, Spain

December Northern Lights Gallery
[previous Decembers: 2008, 2007, 2006, 2005, 2001, 2000]

Explore the Sunspot Cycle

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 21, 2009 there were 1090 potentially hazardous asteroids.
Dec. 2009 Earth-asteroid encounters:
Miss Distance
2009 WV25
Dec. 1
2.9 LD
65 m
2009 WA52
Dec. 5
8.2 LD
23 m
2002 WP
Dec. 6
71.2 LD
950 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.
  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
  more links...
©2008, -- This site is penned daily by Dr. Tony Phillips.













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