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Solar wind
speed: 278.6 km/sec
density: 2.1 protons/cm3
explanation | more data
Updated: Today at 2347 UT
X-ray Solar Flares
6-hr max: C4
1839 UT Apr21
24-hr: C4
1839 UT Apr21
explanation | more data
Updated: Today at: 2300 UT
Daily Sun: 21 Apr 13
Sunspot AR1726 poses a growing threat for Earth-directed flares, probably M-class. Credit: SDO/HMI
Sunspot number: 101
What is the sunspot number?
Updated 21 Apr 2013

Spotless Days
Current Stretch: 0 days
2013 total: 0 days (0%)
2012 total: 0 days (0%)
2011 total: 2 days (<1%)
2010 total: 51 days (14%)
2009 total: 260 days (71%)
Since 2004: 821 days
Typical Solar Min: 486 days

21 Apr 2013

The Radio Sun
10.7 cm flux: 105 sfu
explanation | more data
Updated 21 Apr 2013

Current Auroral Oval:
Switch to: Europe, USA, New Zealand, Antarctica
Planetary K-index
Now: Kp= 1 quiet
24-hr max: Kp= 2
explanation | more data
Interplanetary Mag. Field
Btotal: 4.7 nT
Bz: 0.3 nT south
explanation | more data
Updated: Today at 2347 UT
Coronal Holes: 21 Apr 13
Solar wind flowing from this major coronal hole could reach Earth on April 25-27. Credit: SDO/AIA.
NOAA Forecasts
Updated at: 2013 Apr 21 2200 UTC
0-24 hr
24-48 hr
40 %
40 %
15 %
15 %
Geomagnetic Storms:
Probabilities for significant disturbances in Earth's magnetic field are given for three activity levels: active, minor storm, severe storm
Updated at: 2013 Apr 21 2200 UTC
0-24 hr
24-48 hr
15 %
25 %
05 %
05 %
01 %
01 %
High latitudes
0-24 hr
24-48 hr
15 %
15 %
20 %
30 %
20 %
30 %
Sunday, Apr. 21, 2013
What's up in space

They came from outer space--and you can have one! Genuine meteorites are now on sale in the Space Weather Store.

Own your own meteorite

LYRID METEOR SHOWER PEAKS TONIGHT: Earth is passing through a stream of debris from ancient Comet Thatcher, source of the annual Lyrid Meteor Shower. Usually the shower is mild (10-20 meteors per hour) but unmapped filaments of dust in the comet's tail sometimes trigger outbursts ten times stronger. Forecasters say the best time to look is during the dark hours before local dawn on Monday, April 22nd. [photo gallery]

BIG SUNSPOT BOOSTS ODDS FOR FLARES: The rapid growth of sunspot AR1726 continues. Invisible only two days ago, it is now a behemoth more than 150,000 km (a dozen Earth diameters) wide. A 48-hour movie from the Solar Dynamics Observatory shows the active region's development:

The sunspot has a 'beta-gamma' magnetic field that harbors energy for M-class flares. NOAA forecasters put the odds of an M-class eruption today at 10%, but that is probably an underestimate. AR1726 poses a growing threat for significant Earth-directed flares. Solar flare alerts: text, voice.

SPACE WEATHER BALLOON: Yesterday in the Sierra Nevada mountains near Bishop, California, a group of high school students launched a "space weather balloon" into the stratosphere. Their goal is to monitor the effects of solar flares on Earth's atmosphere. Scroll below the image for more information:

The silver capsule, built by Mihai Ciustea of Sammamish WA and launched by the Earth to Sky team of Bishop CA, is bristling with sensors to measure, e.g., ozone, pressure, humidity, acceleration and other variables of interest. The capsule travels to 125,000 feet--well inside Earth's ozone layer--and lingers there for approximately two hours before parachuting back to Earth with the data. The April 20th launch was a test flight to measure baseline levels when solar activity is relatively low.

The capsule also serves another purpose: It is a bacteria collector. A door at the bottom of the capsule can open, guiding air into a filter designed to capture microbes during the flight. Mihai Ciustea hopes to find ice-nucleating bacteria and other lifeforms living high above Earth's surface. Stay tuned for updates about this mission!

Realtime Space Weather Photo Gallery

Realtime Comet Photo Gallery

Realtime Noctilucent Cloud Photo Gallery
[previous years: 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2011]

  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 21, 2013 there were 1397 potentially hazardous asteroids.
Recent & Upcoming Earth-asteroid encounters:
Miss Distance
2013 GH66
Apr 15
4 LD
10 m
2013 GJ69
Apr 15
7.8 LD
23 m
2013 GH23
Apr 19
5.5 LD
33 m
2005 NZ6
Apr 29
24.9 LD
1.3 km
2001 DQ8
Apr 30
74.3 LD
1.1 km
2004 BV102
May 25
69.9 LD
1.4 km
1998 QE2
May 31
15.2 LD
2.1 km
2000 FM10
Jun 5
50.3 LD
1.3 km
2002 KL3
Jun 6
66.4 LD
1.1 km
1999 WC2
Jun 12
39.2 LD
1.9 km
2006 RO36
Jun 18
70.9 LD
1.2 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 web 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 Dynamics Observatory
  Researchers call it a "Hubble for the sun." SDO is the most advanced solar observatory ever.
  3D views of the sun from NASA's Solar and Terrestrial Relations Observatory
Solar and Heliospheric Observatory
  Realtime and archival images of the Sun from SOHO.
Daily Sunspot Summaries
  from the NOAA Space Environment Center
  the underlying science of space weather
Space Weather Alerts
  more links...
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