Solar Wind
speed: 350.6 km/s
0.3 protons/cm3
explanation | more data
Updated: Today at 2345 UT

X-ray Solar Flares

6-hr max:
B6 2105 UT Dec23
24-hr: B8 0240 UT Dec23
explanation | more data
Updated: Today at 2345 UT

Daily Sun: 23 Dec '05

Sunspot 838 is growing quickly, but it does not yet pose a threat for strong solar flares. Credit: SOHO/MDI

Sunspot Number: 77
What is the sunspot number?
Updated: 22 Dec 2005

Far Side of the Sun

This holographic image reveals no large sunspots on the far side of the sun. Image credit: SOHO/MDI

Interplanetary Mag. Field
Btotal: 4.1 nT
2.5 nT north
explanation | more data
Updated: Today at 2346 UT

Coronal Holes:

A solar wind stream flowing from the indicated coronal hole could reach Earth on or about Dec. 28th or 29th. Image credit: SOHO Extreme UV Telescope.


Solar Flares: Probabilities for a medium-sized (M-class) or a major (X-class) solar flare during the next 24/48 hours are tabulated below.
Updated at 2005 Dec 23 2202 UTC
FLARE 0-24 hr 24-48 hr
CLASS M 05 % 10 %
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 2005 Dec 23 2202 UTC
0-24 hr 24-48 hr
ACTIVE 15 % 15 %
MINOR 05 % 05 %
SEVERE 01 % 01 %

High latitudes
0-24 hr 24-48 hr
ACTIVE 20 % 25 %
MINOR 10 % 10 %
SEVERE 01 % 05 %

What's Up in Space -- 23 Dec 2005
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Auroras for Christmas? It could happen... Sign up for SpaceWeather PHONE.

CHRISTMAS MORNING: Mom, dad, wake up, it's Christmas! If this happens to you at 5:30 a.m. on Dec. 25th, steal a glance out the window on your way to the tree. The crescent moon will be gliding by the bright star Spica--a pretty close encounter. In some places the moon will actually blot out the star. It's a nice way to start the day: sky map.

AN EXPLOSION ON THE MOON: So you thought nothing ever happens on the moon? Think again. NASA scientists have observed a surprising and powerful explosion in the lunar Sea of Rains: full story.

EXPANDING SUNSPOT: It's happening again: For the second time in less than a week, a sunspot is materializing before our very eyes. Just yesterday sunspot 838 was a barely-visible speck. Now it is wider than the planet Neptune:

Sunspot 838: Dec. 21-22, 2005. Credit: SOHO

Sometimes, the magnetic fields of fast-growing sunspots become unstable and explode. The magnetic field of sunspot 838, however, does not appear to harbor energy for strong flares. Stay tuned for updates.

SHRINKING PLANET: If you get a telescope for Christmas, point it at Mars--fast! The red planet is receding from Earth at a speed of 30,000 mph and shrinking as it goes. Using an 8-inch telescope, Joel Warren of Amarillo, Texas, took these two pictures of Mars five weeks apart:

What a difference: By mid-January, Mars will be only half as bright as it is tonight, and its apparent diameter will have decreased from 13 to 9 arcseconds. So now is the time to observe Mars. Look for it straight overhead after sunset: sky map.

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 23 Dec 2005 there were 750 known Potentially
Hazardous Asteroids
December 2005 Earth-asteroid encounters




2005 XA8

Dec. 5

0.6 LD


~35 m
2005 XX

Dec. 9

2.2 LD


~20 m
2005 WC1

Dec. 14

7.9 LD


~370 m
2005 XO66

Dec. 19

5.0 LD


~50 m
Notes: LD is a "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 Web Links

NOAA Space Environment Center -- The official U.S. government bureau for real-time monitoring of solar and geophysical events, research in solar-terrestrial physics, and forecasting solar and geophysical disturbances.

Atmospheric Optics -- the first place to look for information about sundogs, pillars, rainbows and related phenomena. See also Snow Crystals.

Solar and Heliospheric Observatory -- Realtime and archival images of the Sun from SOHO. (European Mirror Site)

Daily Sunspot Summaries -- from the NOAA Space Environment Center.

Current Solar Images --a gallery of up-to-date solar pictures from the National Solar Data Analysis Center at the Goddard Space Flight Center. See also the GOES-12 Solar X-ray Imager.

Recent Solar Events -- a nice summary of current solar conditions from

SOHO Farside Images of the Sun from SWAN and MDI.

The Latest SOHO Coronagraph Images -- from the Naval Research Lab

The Sun from Earth -- daily images of our star from the Big Bear Solar Observatory

List of Potentially Hazardous Asteroids -- from the Harvard Minor Planet Center.

Observable Comets -- from the Harvard Minor Planet Center.

What is the Interplanetary Magnetic Field? -- A lucid answer from the University of Michigan. See also the Anatomy of Earth's Magnetosphere.

Real-time Solar Wind Data -- from NASA's ACE spacecraft. How powerful are solar wind gusts? Read this story from Science@NASA.

More Real-time Solar Wind Data -- from the Solar and Heliospheric Observatory Proton Monitor.

Aurora Forecast --from the University of Alaska's Geophysical Institute

Lists of Coronal Mass Ejections -- from 1998 to 2001

Mirages: Mirages in Finland; An Introduction to Mirages;

NOAA Solar Flare and Sunspot Data: 1996, 1997, 1998, 1999; 2000; 2001; 2002; 2003; 2004; Jan-Mar 2005; Apr-Jun 2005; Jul-Sep 2005; Oct-Dec 2005;

Space Audio Streams: (University of Florida) 20 MHz radio emissions from Jupiter: #1, #2, #3, #4; (NASA/Marshall) INSPIRE: #1; (Stan Nelson of Roswell, New Mexico) meteor radar: #1, #2;

Recent International Astronomical Union Circulars


This site is penned daily by Dr. Tony Phillips: email
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