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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: 372.1 km/s
6.2 protons/cm3
explanation | more data
Updated: Today at 2255 UT

X-ray Solar Flares

6-hr max:
B3 2245 UT Sep20
24-hr: C1 0720 UT Sep20
explanation | more data
Updated: Today at 2245 UT

Daily Sun: 17 Sep '04
Sunspot 673 poses a threat for M-class solar flares. Image credit: SOHO/MDI

The Far Side of the Sun

This holographic image reveals a middling sunspot on the far side of the sun. Image credit: SOHO/MDI

Sunspot Number: 42
What is the sunspot number?
Updated: 19 Sep 2004

Interplanetary Mag. Field
Btotal: 7.1 nT
2.5 nT south
explanation | more data
Updated: Today at 2256 UT

Coronal Holes:

The indicated coronal hole might spray a solar wind stream past Earth on Sept 18th or 19th. Image credit: NOAA's Solar X-ray Imager (SXI)


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 2004 Sep 20 2200 UTC
FLARE 0-24 hr 24-48 hr
CLASS M 10 % 05 %
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 2004 Sep 20 2200 UTC
0-24 hr 24-48 hr
ACTIVE 20 % 40 %
MINOR 10 % 25 %
SEVERE 01 % 10 %

High latitudes
0-24 hr 24-48 hr
ACTIVE 30 % 50 %
MINOR 15 % 30 %
SEVERE 05 % 15 %

What's Up in Space -- 20 Sep 2004
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AURORA WATCH: There is a slim (5% to 10%) chance of high-latitude auroras after nightfall on Sept. 21st. The cause: a lopsided coronal mass ejection (CME) might deliver a glancing blow to Earth's magnetic field. The CME was hurled into space by an M1-class explosion near sunspot 672 on Sept. 19th.

CHANGING SEASONS: Northern autumn is the best time of year to see auroras. Why? Scientists aren't sure, but it's true anyway. Northern autumn--and aurora season--begins this year on Sept 22nd at 1630 UT (9:30 a.m. PDT).

Right: Auroras and a meteor over Harstad, Norway, on Sept. 14th. Photo credit: Frank S. Andreassen.

ANALEMMA: If you took a picture of the sun at the same time each day, would it remain in the same position? The answer is no, and the figure-8 shape traced out by the sun over the course of a year is called an analemma.

Greek photographer Anthony Ayiomamitis created this analemma by combining 48 exposures painstakingly collected between March 30, 2003 and March 23, 2004:

Analemma over the Temple of Zeus, Athens, Greece.

Where will the sun be this week when northern autumn begins? "At the mid-way point between the upper and lower extremities of the figure-8," answers Ayiomamitis. [more]

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 20 Sep 2004 there were 618 known Potentially
Hazardous Asteroids

Sept. 2004 Earth-asteroid encounters


2003 UX34

Sept. 9

22 LD

2004 JA27

Sept. 10

23 LD

1998 OX4

Sept. 14

25 LD


Sept. 29

4 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 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

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; 2003; Jan-Mar., 2004;

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


Editor's Note: This site is sponsored by Science@NASA. Space weather and other forecasts that appear here are formulated by Dr. Tony Phillips. They are not guarantees of space weather or other celestial activity.

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