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<<back forward>> -- News and information about meteor showers, solar flares, auroras, and near-Earth asteroids
Science news and information about the Sun-Earth environment.


Solar Wind
speed: 329.1 km/s
5.6 protons/cm3
explanation | more data
Updated: Today at 2245 UT

X-ray Solar Flares
6-hr max:
A0 2245 UT Apr20
24-hr: A0 2245 UT Apr20
explanation | more data
Updated: Today at 2245 UT

Daily Sun: 20 Apr '07

The sun is blank--no sunspots. Credit: SOHO/MDI

Sunspot Number: 0
What is the sunspot number?
Updated: 19 Apr 2007

Far Side of the Sun

This holographic image revealsno sunspots on the far side of the sun. Image credit: SOHO/MDI

Interplanetary Mag. Field
Btotal: 2.7 nT
0.8 nT south
explanation | more data
Updated: Today at 2246 UT

Coronal Holes:

A solar wind stream flowing from the indicated coronal hole should reach Earth on April 21st or 22nd. 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 2007 Apr 20 2203 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 2007 Apr 20 2203 UTC
0-24 hr 24-48 hr
ACTIVE 35 % 25 %
MINOR 15 % 10 %
SEVERE 05 % 01 %

High latitudes
0-24 hr 24-48 hr
ACTIVE 40 % 30 %
MINOR 25 % 15 %
SEVERE 10 % 05 %

What's Up in Space -- 20 Apr 2007
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AURORA WATCH: A solar wind stream is heading for Earth and it could cause a geomagnetic storm when it arrives on April 21st or 22nd. Sky watchers from Scandinavia to Alaska should be alert for auroras.

GET READY FOR 3D: On Monday, April 23rd, NASA will release, for the first time, 3-dimensional photos of the sun taken by the STEREO spacecraft. Magnetic loops, prominences and plumes will practically leap out of your computer screen. (continued below)

These images will be displayed on big screens at science centers around the USA (list) and posted on the internet. Get ready this weekend by buying or building some 3D glasses--and stay tuned for Monday!

WESTERN LIGHTS: The crescent Moon and Venus are so bright, you can see them while the sky is still blue. Step outside this evening at sunset and look west into the twilight:

Photo details: Canon 30D, 28mm lens, ISO 500, 30 seconds, Spectralstar filter

Kim L. Graham took this picture on April 19th from Madison Lake, Ohio. She used a SpectralStar filter to give the Moon and Venus added flourish.

Later tonight when the sky fades to black and the stars come out, watch the crescent Moon glide by Elnath, a dying star in Taurus: sky map.

more images: from Pete Lawrence of Selsey, West Sussex, UK; from Babak A. Tafreshi near Tehran, Iran; from Dan Bush of Albany, Missouri; from Szymon Kozlowski at the Jodrell Bank Observatory in Cheshire, UK; from Guillaume Bertrand of Saint Laurent sur Sèvre, France; from Maximilian Teodorescu of Magurele, Romania; from Ronan Newman at the Turlough Round Tower, an 800-year-old Celtic monastery; from Mohammad Taher Pilevar of Hamedan, Iran.

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 20 Apr 2007 there were 858 known Potentially
Hazardous Asteroids

April 2007 Earth-asteroid encounters




2006 VV2

Mar. 31

8.8 LD


2 km
2007 FY20

Apr. 2

5.3 LD


50 m
2007 DS84

Apr. 14

16 LD


325 m
2007 GU1

Apr. 16

2.1 LD


45 m
2007 HA

Apr. 17

6.5 LD


300 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.

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 -- from the National Solar Data Analysis Center

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

What is the Magnetosphere?

The Lion Roars -- visit this site to find out what the magnetosphere sounds like.

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

Observable Comets -- from the Harvard Minor Planet Center.

Real-time Solar Wind Data -- from NASA's ACE spacecraft.

How powerful are solar wind gusts? Not very! Read this story from Science@NASA.

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

Lists of Coronal Mass Ejections -- from 1996 to 2006

Mirages: Mirages in Finland; An Introduction to Mirages;

NOAA Solar Flare and Sunspot Data: 1994, 1995, 1996, 1997, 1998, 1999; 2000; 2001; 2002; 2003; 2004; 2005; Jan-Mar 2006; Apr-Jun 2006; Jul-Sep 2006; Oct-Dec 2006.

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

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