Science news and information about the Sun-Earth environment.


Solar Wind

speed: 530.3 km/s
1.8 protons/cm3
explanation | more data
Updated: Today at 1625 UT

X-ray Solar Flares

6-hr max:
C1 1355 UT Sep21
24-hr: C1 0005 UT Sep21
explanation | more data
Updated: Today at 1625 UT

Daily Sun : 21 Sep '03
A large sunspot is emerging over the sun's eastern limb. It is too soon to know if it poses a threat for powerful flares. Image credit: SOHO MDI

The Far Side of the Sun

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

Sunspot Number : 72
What is the sunspot number?
Updated: 20 Sep 2003

Coronal Holes:

Earth is inside a solar wind stream flowing from the indicated coronal hole. Image credit: SOHO Extreme UV Telescope
More about coronal holes

Interplanetary Mag. Field
Btotal: 4.4 nT
0.2 nT north
explanation | more data
Updated: Today at 1627 UT


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 2003 Sep 20 2200 UTC
FLARE 0-24 hr 24-48 hr
CLASS M 20 % 20 %
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 2003 Sep 20 2200 UTC
0-24 hr 24-48 hr
ACTIVE 40 % 45 %
MINOR 25 % 20 %
SEVERE 10 % 05 %

High latitudes
0-24 hr 24-48 hr
ACTIVE 25 % 30 %
MINOR 35 % 25 %
SEVERE 20 % 15 %

What's Up in Space -- 21 Sep 2003
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SPACE STATION FLYBYS: For the next few days, the International Space Station (ISS) will appear in evening skies over North America. It's easy to see. The station moves slowly across the sky, unblinking, about as bright as the planet Mars.

Would you like a phone call to alert you when the ISS flys over your home town? Try Spaceweather PHONE.

Right: Italian amateur astronomer Paolo Beltrame captured this short video of the space station using his 8" telescope and a Toucam Pro web camera.

AURORA WATCH: Sky watchers from Alaska to Michigan have seen auroras in recent days. They were caused by a high speed solar wind stream buffeting our planet's magnetic field. Earth is exiting the stream now, so geomagnetic activity should subside tonight.

HURRICANE HALOS: "Halos around the sun often presage bad weather," says atmospheric optics expert Les Cowley. The reason: "Cirrostratus clouds on the leading edge of storm fronts contain halo-forming ice crystals." Such was the case on Sept. 18th when Hurricane Isabel hit the United States. Sky watcher Bob Colwell took this picture from Berwick, Maine:

"These halos were the brightest that I have ever witnessed in New England," says Colwell. "They included a 22° ring around the sun, a circumscribed halo, sundogs, and a complete parhelic circle. The display lasted more than 2 hours while the outer edge of the Isabel's clouds passed overhead, then the sky cleared up completely for a while." More pictures: #1, #2, #3, #4.

Isabel is gone now, but don't stop looking for halos, encourages Cowley. "Halos don't necessarily mean rain and storms--good weather cirrus can cause them, too."

SEC IN PERIL: NOAA's Space Environment Center (SEC), the source of fundamental data for and others, is facing severe budget cuts in FY2004. In the worst case, the SEC could cease to exist--a true calamity for space weather forecasters. Want to help? Contact the University of Colorado's Brad Udall.

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 are on a collision course with our planet, although astronomers are finding new ones all the time.

On 21 Sep 2003 there were 530 known Potentially
Hazardous Asteroids

September 2003 Earth-asteroid encounters



2003 RS1

Sept. 2

13 LD

2003 RB5

Sept. 4

11 LD

2003 RM10

Sept. 5

10 LD

2003 RB

Sept. 28

38 LD

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 magni

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 --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 Soft 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

Daily Solar Flare and Sunspot Data -- from the NOAA Space Environment Center.

Lists of Coronal Mass Ejections -- from 1998 to 2001

What is an Iridium flare? See also Photographing Satellites by Brian Webb.

Vandenberg AFB missile launch schedule.

What is an Astronomical Unit, or AU ?

Mirages: Mirages in Finland; An Introduction to Mirages;

NOAA Solar Flare and Sunspot Data: 1999; 2000; 2001; 2002; Jan-Mar., 2003; Apr-Jun., 2003;

Recent International Astronomical Union Circulars






Editor's Note : Space weather and other forecasts that appear on this site are formulated by Dr. Tony Phillips. They are not official statements of any government agency (including NASA) nor should they be construed as guarantees of space weather or other celestial activity.

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Dr. Tony Phillips
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