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<<back forward>> -- News and information about meteor showers, solar flares, auroras, and near-Earth asteroids
Current conditions
Solar wind
speed: 449.9 km/sec
density: 0.8 protons/cm3
explanation | more data
Updated: Today at 2346 UT
X-ray Solar Flares
6-hr max: A0
2340 UT Apr20
24-hr: A0
2340 UT Apr20
explanation | more data
Updated: Today at: 2340 UT
Daily Sun: 20 Apr 09
The sun is blank--no sunspots. Credit: SOHO/MDI
Sunspot number: 0
What is the sunspot number?
Updated 20 Apr 2009

NEW: Spotless Days
Current Stretch: 25 days
2009 total: 97 days (88%)
Since 2004: 608 days
Typical Solar Min: 485 days
explanation | more info
Updated 20 Apr 2009

Far side of the Sun:
This holographic image reveals no sunspots on the far side of the sun. Image credit: SOHO/MDI
Planetary K-index
Now: Kp= 0 quiet
24-hr max: Kp= 2
explanation | more data
Current Auroral Oval:
Switch to: Europe, USA, New Zealand, Antarctica
What is the auroral oval?
Interplanetary Mag. Field
Btotal: 3.4 nT
Bz: 0.6 nT south
explanation | more data
Updated: Today at 2347 UT
Coronal Holes:
There are no large coronal holes on the Earth-facing side of the sun. Credit: SOHO Extreme UV Telescope
NOAA Forecasts
Updated at: 2009 Apr 20 2201 UTC
0-24 hr
24-48 hr
01 %
01 %
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: 2009 Apr 20 2201 UTC
0-24 hr
24-48 hr
10 %
10 %
05 %
05 %
01 %
01 %
High latitudes
0-24 hr
24-48 hr
15 %
10 %
05 %
05 %
01 %
01 %
What's up in Space
April 20, 2009

AURORA ALERT: Did you sleep through the Northern Lights? Next time get a wake-up call: Spaceweather PHONE.


MORNING SPACECRAFT: The International Space Station (ISS) is about to perform a series of early-morning flybys over North America. The recently-expanded station is even brighter than the planet Venus and it looks marvelous gliding silently through the rosy glow of dawn. Check the Simple Satellite Tracker for viewing times.

MORNING PLANETS: The ISS is not alone. The Moon, Venus, Mars and Jupiter are also up at dawn: sky map. Photographer Liz Gleeson sends this picture of Venus and Mars rising over Magnetic Island in North Queensland, Australia on April 18th:

"Venus was so bright, it was visible through clouds," she says. "To take the picture I used a Canon 450D set at ISO 400 for four seconds."

Readers, keep an eye on Venus this week. The crescent Moon is converging on the planet for a spectacular close encounter at dawn on Wednesday, April 22nd. Viewed from western parts of North America, the Moon will actually eclipse Venus. The event begins just after 5 am Pacific Daylight Time. Science@NASA has the full story.

morning sky maps: April 20, 21, 22.

MORNING METEORS: Earth is entering a stream of dusty debris from Comet Thatcher, source of the annual Lyrid meteor shower. Forecasters expect the shower to peak during the dark hours before dawn on Wednesday, April 22nd, when observers should count 10 to 20 meteors per hour: more information.

Got clouds? No problem. If you can't see the shower, you can listen to it on Space Weather Radio. We are streaming live signals from the Air Force Space Surveillance Radar in Texas. Whenever a meteor passes overhead--ping!--there is an echo. The Lyrids should produce a surge of activity on April 22nd.

On April 2nd, ham radio operator Stan Nelson of Roswell, New Mexico, was listening to the radar's signals when the International Space Station and a meteor passed through the beam in quick succession. Click on the dynamic spectrum to listen:

audio: with noise reduction | w/o noise reduction

The slowly descending tone at the beginning of the soundtrack is the radar's doppler-shifted reflection from the ISS. It sounds like the whistle of a train racing past a stationary bystander. Indeed, the basic physics of the doppler shift is the same in both cases.

The rapidly descending tone near the end of the soundtrack is the radar's doppler-shifted reflection from a meteor. Because meteors travel through space some two to ten times faster than Earth-orbiting spacecraft, their radar reflections are much more sharply doppler shifted.

On April 22nd you might hear both kinds of reflections as Lyrid meteors and various Earth-orbiting satellites pass over the radar facility. Tune in!

April 2009 Aurora Gallery
[previous Aprils: 2008, 2007, 2006, 2005, 2004, 2003, 2002]

Explore the Sunspot Cycle

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.
On April 20, 2009 there were 1049 potentially hazardous asteroids.
April 2009 Earth-asteroid encounters:
Miss Distance
2009 FU30
Apr. 2
8.8 LD
44 m
2004 VC
Apr. 3
51.3 LD
785 m
2002 EB3
Apr. 10
41.3 LD
1.3 km
2003 SG170
Apr. 19
57.7 LD
1.2 km
2009 FJ30
Apr. 24
9.7 LD
130 m
2001 VG5
Apr. 26
58.5 LD
2.1 km
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 space weather bureau
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.
  3D views of the sun from NASA's Solar and Terrestrial Relations Observatory
Daily Sunspot Summaries
  from the NOAA Space Environment Center
Current Solar Images
  from the National Solar Data Analysis Center
Science Central
  more links...
©2008, -- This site is penned daily by Dr. Tony Phillips.
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