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Solar wind
speed: 517.9 km/sec
density: 2.6 protons/cm3
explanation | more data
Updated: Today at 2347 UT
X-ray Solar Flares
6-hr max: B7
1713 UT Aug21
24-hr: C2
0743 UT Aug21
explanation | more data
Updated: Today at: 2300 UT
Daily Sun: 21 Aug 13
New sunspot AR1827 has a 'beta-gamma' magnetic field that poses a threat for M-class solar flares. Credit: SDO/HMI
Sunspot number: 115
What is the sunspot number?
Updated 21 Aug 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

Update
21 Aug 2013

The Radio Sun
10.7 cm flux: 132 sfu
explanation | more data
Updated 21 Aug 2013

Current Auroral Oval:
Switch to: Europe, USA, New Zealand, Antarctica
Credit: NOAA/POES
Planetary K-index
Now: Kp= 4 unsettled
24-hr max: Kp= 4
unsettled
explanation | more data
Interplanetary Mag. Field
Btotal: 8.2 nT
Bz: 0.9 nT north
explanation | more data
Updated: Today at 2347 UT
Coronal Holes: 21 Aug 13
Solar wind flowing from the indicated coronal hole should reach Earth on Aug. 23-24. Credit: SDO/AIA.

Spaceweather.com is now posting daily satellite images of noctilucent clouds (NLCs), which hover over Earth's poles at the edge of space. The data come from NASA's AIM spacecraft. The north polar "daisy" pictured below is a composite of near-realtime images from AIM assembled by researchers at the University of Colorado's Laboratory for Atmospheric and Space Physics (LASP).
Noctilucent Clouds
Switch view: Europe, USA, Asia, Polar
Updated at: 08-21-2013 14:55:03
SPACE WEATHER
NOAA Forecasts
Updated at: 2013 Aug 21 2200 UTC
FLARE
0-24 hr
24-48 hr
CLASS M
10 %
10 %
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: 2013 Aug 21 2200 UTC
Mid-latitudes
0-24 hr
24-48 hr
ACTIVE
25 %
30 %
MINOR
05 %
10 %
SEVERE
01 %
01 %
High latitudes
0-24 hr
24-48 hr
ACTIVE
15 %
15 %
MINOR
25 %
30 %
SEVERE
30 %
45 %
 
Wednesday, Aug. 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

ANOTHER CME IS ON THE WAY: As Earth passes through the wake of one CME, which did little to stir geomagnetic activity on Aug. 20th, another CME is on the way. NOAA forecasters expect a coronal mass ejection hurled into space yesterday by an erupting magnetic filament to deliver a glancing blow to Earth's magnetic field on Aug. 23rd. High-latitude sky watchers should be alert for auroras. Aurora alerts: text, voice.

SUNDIVING COMET AND FULL-HALO CME: A small comet plunged into the sun on August 20th. Just before it arrived, the sun expelled a magnificent full-halo CME. Click to view a movie from the Solar and Heliospheric Observatory (SOHO):

In the final frames of the movie, the comet can be seen furiously vaporizing. Indeed, those were the comet's final frames. It did not emerge again from its flyby of the hot sun. "With a diameter of perhaps a few tens of meters, this comet was clearly far too small to survive the intense bombardment of solar radiation," comments Karl Battams of the Naval Research Lab, who studies sungrazing comets.

The CME (coronal mass ejection) came from an explosion on the farside of the sun. Although the CME and the comet appear to intersect, there was probably no interaction between the two. The comet is in the foreground and the farside CME is behind it.

Occasionally, readers ask if sundiving comets can trigger solar explosions. There's no known mechanism for comets to spark solar flares. Comets are thought to be too small and fragile to destabilize the sun's magnetic field. Plus, this comet was still millions of kilometers from the sun when the explosion unfolded.

The comet, R.I.P., was a member of the Kreutz family. Kreutz sungrazers are fragments from the breakup of a single giant comet many centuries ago. They get their name from 19th century German astronomer Heinrich Kreutz, who studied them in detail. Several Kreutz fragments pass by the sun and disintegrate every day. Most, measuring less than a few meters across, are too small to see, but occasionally a bigger fragment like this one attracts attention.

TRUE BLUE MOON? Was last night's full Moon a "Blue Moon?" Some observers say "yes," but not because the Moon turned blue. Behold this picture of last night's moonrise over Volterraio Castle on the Island of Elba, Italy, then scroll down for further discussion:

"The Full Moon of Aug. 20-21 is a 'seasonal Blue Moon,'" explains photographer Stefano De Rosa, "because it is the third of four full moons in a single season."

But wait--isn't a Blue Moon the second full Moon in a calendar month? That would be the modern definition, which became popular in the late 20th century. De Rosa's definition is an older and, some would say, truer definition of "Blue Moon."

Which definition is correct? Both and neither. It's all folklore! The only true-blue Moon is a Moon that actually turns blue. And, yes, that can happen. Under certain circumstances volcanic dust and ash from forest fires can scatter the reds out of moonlight, leaving only a blue-cratered disk behind.

Realtime Space Weather Photo Gallery


Realtime Aurora Photo Gallery


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


Realtime Comet Photo Gallery

  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 August 21, 2013 there were 1397 potentially hazardous asteroids.
Recent & Upcoming Earth-asteroid encounters:
Asteroid
Date(UT)
Miss Distance
Size
1999 CF9
Aug 23
24.7 LD
1.1 km
2013 QR1
Aug 25
8.3 LD
225 m
2002 JR9
Aug 31
63.5 LD
1.4 km
2013 PX6
Sep 21
68.6 LD
1.0 km
1992 SL
Sep 23
70 LD
1.0 km
2000 DK79
Nov 10
49.1 LD
3.2 km
2011 JY1
Nov 13
8.2 LD
57 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 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.
STEREO
  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
Heliophysics
  the underlying science of space weather
Space Weather Alerts
   
  more links...
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