You are viewing the page for Dec. 25, 2008
  Select another date:
<<back forward>> -- News and information about meteor showers, solar flares, auroras, and near-Earth asteroids
Current conditions
Solar wind
speed: 437.0 km/sec
density: 0.9 protons/cm3
explanation | more data
Updated: Today at 2247 UT
X-ray Solar Flares
6-hr max: A0
2245 UT Dec25
24-hr: A2
1300 UT Dec25
explanation | more data
Updated: Today at: 2245 UT
Daily Sun: 25 Dec 08
The Earth-facing side of the sun is blank--no sunspots. Credit: SOHO/MDI
Sunspot number: 0
What is the sunspot number?
Updated 24 Dec. 2008
Far side of the Sun:
This holographic image reveals a southern hemisphere sunspot on the far side of the sun. Image credit: SOHO/MDI
Planetary K-index
Now: Kp= 1 quiet
24-hr max: Kp= 2
explanation | more data
Current Auroral Oval:
Switch to: Europe, USA, New Zealand, Antarctica
What is the auroral oval?
Interplanetary Mag. Field
Btotal: 2.2 nT
Bz: 0.2 nT south
explanation | more data
Updated: Today at 2247 UT
Coronal Holes:
A solar wind stream flowing from the indicated coronal hole should arrive on or about Dec. 29th. Credit: SOHO Extreme UV Telescope
NOAA Forecasts
Updated at: 2008 Dec 25 2201 UTC
0-24 hr
24-48 hr
01 %
01 %
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 25 2201 UTC
0-24 hr
24-48 hr
05 %
01 %
01 %
01 %
01 %
01 %
High latitudes
0-24 hr
24-48 hr
10 %
05 %
01 %
01 %
01 %
01 %
What's up in Space
December 25, 2008

UNIQUE CHRISTMAS GIFT: 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.


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;

EDGE-ON FOR THE HOLIDAYS: You look through the telescope. Blink. Shake your head and look again. The planet you expected to see in the eyepiece is not the one that's actually there. Too much eggnog? No, it's just Saturn's crazy Christmas tilt:

Amateur astronomer Paulo Casquinha took the picture last night from his backyard observatory in Quinta do Anjo, Portugal. It shows how Saturn's rings are almost edge-on to Earth this holiday season. Viewed from the side, the normally wide and bright rings have become a shadowy line bisecting Saturn's two hemispheres--a scene of rare beauty.

"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)

NACREOUS CLOUDS: In the stratosphere above Scandinavia, the winter air temperature has dropped below -85 C. That's a magic value. At such temperatures, tiny crystals of ice begin to form in the desert-dry air 9 to 16 miles high. And when that happens, voilĂ --nacreous clouds:

"This one appeared after sunset on Christmas Eve," says Tor Aslesen of Oslo, Norway, who snapped the picture using his Nikon D50. "It was almost florescent, the way it stood out against the darker twilight sky."

Nacreous clouds are a polar phenomenon. They get their intense colors from sunlight striking ice crystals ~10 microns in diameter. Diffraction produces iridescence, a phenomenon familiar to daytime sky watchers around the world. Unlike the relatively pale iridescent clouds of mid-latitudes, however, polar nacreous clouds are blow-your-Christmas-socks-off bright.

Northern winter is just beginning and the polar stratosphere will grow even icier in the weeks ahead. Sky watchers in cold places like Scandinavia, Iceland and Alaska should be alert for nacreous colors; the best time to look is during the twilight hours after sunset or before sunrise.

Dec. 2008 Nacreous Cloud Gallery
[January 2008 Gallery] [Nacreous tutorial]

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 25, 2008 there were 1012 potentially hazardous asteroids.
Dec. 2008 Earth-asteroid encounters:
Miss Distance
2008 WY94
Dec. 5
3.2 LD
35 m
2008 WG14
Dec. 5
4.8 LD
49 m
2008 XK
Dec. 6
1.7 LD
15 m
2008 XC1
Dec. 12
4.3 LD
102 m
2008 XB2
Dec. 13
5.8 LD
47 m
2006 VB14
Dec. 14
36 LD
795 m
2008 EV5
Dec. 23
8.4 LD
435 m
2008 YQ2
Dec. 24
8.6 LD
49 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
  a one-stop hub for all things scientific
  more links...
©2008, -- This site is penned daily by Dr. Tony Phillips.
©2019 All rights reserved.