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SpaceWeather.com -- News and information about meteor showers, solar flares, auroras, and near-Earth asteroids
SPACE WEATHER
Current conditions
Solar wind
speed: 434.1 km/sec
density: 1.7 protons/cm3
explanation | more data
Updated: Today at 2245 UT
X-ray Solar Flares
6-hr max: A0
2245 UT Apr28
24-hr: A0
2245 UT Apr28
explanation | more data
Updated: Today at: 2245 UT
Daily Sun: 28 Apr 08
The sun is blank--no sunspots. Credit: SOHO/MDI
Sunspot number: 0
What is the sunspot number?
Updated 27 Apr 2008
Far side of the Sun:
This holographic image reveals no sunspots on the farside of the sun. Image credit: SOHO/MDI
Planetary K-index
Now: Kp= 3 quiet
24-hr max: Kp= 3
quiet
explanation | more data
Current Auroral Oval:
Switch to: Europe, USA, New Zealand, Antarctica
Credit: NOAA/POES
What is the auroral oval?
Interplanetary Mag. Field
Btotal: 4.2 nT
Bz: 2.1 nT south
explanation | more data
Updated: Today at 2246 UT
Coronal Holes:
A minor solar wind stream flowing from this small coronal hole could reach Earth on or about April 30th. Credit: SOHO Extreme UV Telescope
SPACE WEATHER
NOAA Forecasts
Updated at: 2008 Apr 28 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: 2008 Apr 28 2203 UTC
Mid-latitudes
0-24 hr
24-48 hr
ACTIVE
20 %
30 %
MINOR
05 %
05 %
SEVERE
01 %
05 %
High latitudes
0-24 hr
24-48 hr
ACTIVE
40 %
45 %
MINOR
10 %
15 %
SEVERE
05 %
05 %
What's up in Space
April 28, 2008
FLYBY ALERT! Would you like a phone call when the International Space Station (ISS) is about to fly over your back yard? Sign up for Space Weather PHONE.  

SATURN AND REGULUS: When the sun sets tonight, go outside and look south. You'll find a pair of starry eyes staring back at you. On the left is Saturn, on the right Regulus. The ringed planet and the first-magnitude star are only 2o apart--a pretty pair: sky map.

SOLAR BLAST: No sunspots? No problem. On April 26th the blank sun unleashed a solar flare without the usual aid of a sunspot. At 1408 UT, Earth-orbiting satellites detected a surge of X-rays registering B3.8 on the Richter scale of solar flares. Shortly thereafter, SOHO coronagraphs recorded a coronal mass ejection (CME) billowing away from the sun:

The expanding cloud could deliver a glancing blow to Earth's magnetic field late on April 28th or 29th. High-latitude sky watchers should be alert for auroras when it arrives.

This strange solar flare came from a patch of sun (N08,E08) where magnetic fields were not intense enough to form a visible sunspot (sunspots are made of magnetism). Nevertheless, magnetic fields were present with sufficient energy and instability to produce a powerful explosion. NASA's twin STEREO spacecraft, observing the sun from widely separated vantage points, recorded a million mph shock wave or "solar tsunami" spreading from the blast site through the sun's atmosphere: movie.

Not bad for a "blank sun." Stay tuned for updates.

more images: from David Strange of Branscombe, Devon, UK; from Emiel Veldhuis of Zwolle, the Netherlands; from Stephen Ames of Hodegenville, KY; from Will Gater of Bristol, UK; from Patricia Cannaerts of Belgium; from Joel Bavais of Anvaing, Belgium;

IRIDIUM FLARES 24-7: Anyone who's ever seen an Iridium satellite flaring in the night sky knows what it must be like to witness a supernova. Sudden. Breath-taking. Unforgettable.

At the South Pole, the unforgettable happens 160 times a day. R. Dana Hrubes sends this report from the Amundsen-Scott South Pole Station where all six orbital planes of the polar orbiting Iridium satellites cross: "The sun has set here for 6 months and we get Iridium flares every 9 minutes and 8 seconds for 4 to 5 days at a time." Indeed, such a "flare session" is underway now.

This April 28th self-portrait shows Hrubes with a flare in the background near the Southern Cross. The brilliant flash of light occurred when sunlight glinted off one of the satellite's flat surfaces. "I took this picture and three others using my Canon Rebel XTI 400D," says Hrubes. "The brightest magnitude -8 flares occur every 9 min for an entire day! We routinely use the Iridium satellites for communication from the Pole."


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. [comment]
On April 28, 2008 there were 946 potentially hazardous asteroids.
April-May 2008 Earth-asteroid encounters:
Asteroid
Date(UT)
Miss Distance
Mag.
Size
2008 FH5
Apr. 2
7.6 LD
20
17 m
2001 QO142
Apr. 6
34 LD
17
685 m
2008 GF1
Apr. 7
0.8 LD
18
10 m
2005 BE2
Apr. 10
62 LD
18
1.0 km
2005 NB7
Apr. 17
16 LD
16
705 m
2008 FU6
Apr. 22
62 LD
16
1.4 km
2005 TB
Apr. 28
47 LD
18
1.3 km
2008 HJ
Apr. 29
2.8 LD
16
34 m
2001 DQ8
Apr. 30
74 LD
17
1.1 km
2008 HG
May 5
17 LD
18
90 m
2008 DE
May 9
17 LD
16
550 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 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.
Daily Sunspot Summaries
  From the NOAA Space Environment Center
Current Solar Images
  from the National Solar Data Analysis Center
  more links...
©2008, SpaceWeather.com -- This site is penned daily by Dr. Tony Phillips.
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