You are viewing the page for Jan. 21, 2004
  Select another date:
<<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: 446.3 km/s
3.1 protons/cm3
explanation | more data
Updated: Today at 2243 UT

X-ray Solar Flares

6-hr max:
B7 1720 UT Jan21
24-hr: C2 0035 UT Jan21
explanation | more data
Updated: Today at 2245 UT

Daily Sun: 21 Jan '04
Sunspot 540 poses a slim threat for X-class solar flares. Image credit: SOHO/MDI

The Far Side of the Sun

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

Sunspot Number: 94
What is the sunspot number?
Updated: 20 Jan 2004

Interplanetary Mag. Field
Btotal: 5.3 nT
1 nT south
explanation | more data
Updated: Today at 2255 UT

Coronal Holes:

There are no big coronal holes on the Earth-facing side of the sun today. 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 2004 Jan 21 2200 UTC
FLARE 0-24 hr 24-48 hr
CLASS M 25 % 25 %
CLASS X 05 % 05 %

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 Jan 21 2200 UTC
0-24 hr 24-48 hr
ACTIVE 45 % 30 %
MINOR 25 % 15 %
SEVERE 15 % 05 %

High latitudes
0-24 hr 24-48 hr
ACTIVE 45 % 35 %
MINOR 30 % 20 %
SEVERE 15 % 10 %

What's Up in Space -- 21 Jan 2004
Subscribe to Space Weather News!

Would you like a call when auroras appear in your area? Sign up for Spaceweather PHONE.

AURORA OUTLOOK: A coronal mass ejection (CME, pictured right) is heading for Earth, and it will probably arrive on Jan. 22nd UT. North American sky watchers should be alert for auroras after nightfall on Jan. 21st. The approaching cloud was hurled into space by an C6-category explosion near sunspot 540 on Jan. 20th.

UPDATE: Another coronal mass ejection (movie) left the sun today, Jan. 21st at approximately 0530 UT, and it will sweep past Earth on Jan. 23rd or 24th. More auroras are possible then.

FALSE AURORAS: "I was just about to retire for the night when I looked outside and thought I saw auroras," says Canadian Lauri Kangas, "so I bundled up, grabbed my camera and headed outside." This is what he photographed:

In fact, these are not auroras. They are light pillars caused by city lights glinting through ice crystals in the air. "The temperature was -24C," continues Lauri, "but there was no wind and I could feel the ice crystals falling from the sky like drizzle. When I looked straight up the pillars almost converged. These were the tallest light pillars I have ever seen or photographed." More images: #1, #2, #3, #4.

As lovely as light pillars can be, they are also troubling. Reader Scott Griswald notes that "these pillars show how much light is shining up into the air rather than down on the ground where it is needed." Light pollution wipes out stars and meteor showers, and overwhelms genuine auroras. "The loss of our night sky will mean the eventual loss of wonder for future generations."

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 Jan 2004 there were 569 known Potentially
Hazardous Asteroids

December 2003 Earth-asteroid encounters


2003 YS17

Jan 14

14 LD

2001 BE10

Jan 15

23 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.

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: This site is sponsored by Science@NASA. Space weather and other forecasts that appear here are formulated by Dr. Tony Phillips. They should not be construed as guarantees of space weather or other celestial activity.

You are visitor number 29451447 since January 2000.
©2013 All rights reserved.