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Solar wind
speed: 358.0 km/sec
density: 4.6 protons/cm3
explanation | more data
Updated: Today at 2347 UT
X-ray Solar Flares
6-hr max: B6
2239 UT Sep23
24-hr: B6
2239 UT Sep23
explanation | more data
Updated: Today at: 2300 UT
Daily Sun: 23 Sep 13
Solar activity is low. Only sunspot AR1850 is crackling with low-level B- and C-class flares. Credit: SDO/HMI
Sunspot number: 98
What is the sunspot number?
Updated 23 Sep 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

23 Sep 2013

The Radio Sun
10.7 cm flux: 111 sfu
explanation | more data
Updated 23 Sep 2013

Current Auroral Oval:
Switch to: Europe, USA, New Zealand, Antarctica
Planetary K-index
Now: Kp= 2 quiet
24-hr max: Kp= 2
explanation | more data
Interplanetary Mag. Field
Btotal: 3.9 nT
Bz: -0.0 nT
explanation | more data
Updated: Today at 2347 UT
Coronal Holes: 23 Sep 13
Solar wind flowing from this coronal hole could reach Earth on Sept. 23-24. Credit: SDO/AIA. 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: 09-02-2013 11:55:02
NOAA Forecasts
Updated at: 2013 Sep 23 2200 UTC
0-24 hr
24-48 hr
05 %
05 %
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 Sep 23 2200 UTC
0-24 hr
24-48 hr
10 %
05 %
01 %
01 %
01 %
01 %
High latitudes
0-24 hr
24-48 hr
15 %
15 %
25 %
15 %
10 %
05 %
Monday, Sep. 23, 2013
What's up in space

Listen to radar echoes from satellites and meteors, live on listener-supported Space Weather Radio.

Spaceweather Radio is on the air

SLIGHT CHANCE OF STORMS: NOAA forecasters estimate a 10% chance of polar geomagnetic storms on Sept. 23-24. That's when a minor CME could deliver a glancing blow to Earth's magnetic field. Arctic sky watchers should be alert for auroras. Aurora alerts: text, voice.

COMET ISON IN MOTION: Comet ISON is falling toward the sun for a close encounter on Thanksgiving Day 2013. If it survives, it could become one of the finest comets in years. At the moment ISON is still far away and faint, but its sunward velocity is impressive--more than 72,000 mph on Sept. 22nd. Click on the image to see the comet in motion:

Alberto Quijano Vodniza of Pasto, Narino, Colombia, obtained the 35-minute video on Sept 22nd. "The motion of the comet was clearly visible," he says. "I used a 14-inch Celestron telescope and a STL-1001E SBIG camera."

Comet ISON is now approaching Mars in the eastern sky before sunrise. On Oct. 1st it will fly past the Red Planet at a distance on only 0.07 AU. Mars satellites and rovers are in position to snap the first close-up pictures of the comet. Until then, browse the Comet ISON Photo Gallery where pictures from Earth are already pouring in.

Realtime Comet ISON Photo Gallery

AURORAS LOVE EQUINOXES: Northern autumn and southern spring began yesterday, Sept. 22nd, when the Sun crossed the equator heading south. The crossing also marked the beginning of aurora season. For reasons researchers do not fully understand, auroras love equinoxes. At this time of year, even gentle gusts of solar wind can spark a nice display of Northern Lights:

Marianne Bergli of Tromsø, Norway, took the picture on September 20th. A geomagnetic storm was not underway. It was just a typical night around the beginning of autumn.

"With almost gale force winds it very difficult to stop the camera shaking," says Bergli. "Fortunately the temperature was a very warm 14 C. Auroras filled the sky for about a half-hour before midnight. It was an incredible night with the moon just starting to wane over the mountains at Rekvikeidet."

Realtime Aurora Photo Gallery

CORONAL HOLE: NASA's Solar Dynamics Observatory is monitoring a coronal hole in the sun's northern hemisphere. It is the UV-dark region in this image taken during the early hours of Sept. 21st:

The white lines in the image trace the sun's magnetic field. A coronal hole is a place where the magnetic field spreads apart, allowing solar wind to escape. A stream of solar wind flowing from this particular coronal hole is heading for Earth, due to arrive on Sept. 23-24. Its arrival could add to the impact of a minor CME expected to reach Earth at about the same time. Polar geomagnetic storms are possible early next week. Aurora alerts: text, voice.

Realtime Space Weather 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 September 23, 2013 there were 1429 potentially hazardous asteroids.
Recent & Upcoming Earth-asteroid encounters:
Miss Distance
2013 RF74
Sep 18
5.5 LD
26 m
2013 RZ53
Sep 18
0.6 LD
3 m
2000 DK79
Nov 10
49.1 LD
3.0 km
2011 JY1
Nov 13
8.2 LD
57 m
2001 AV43
Nov 18
3 LD
52 m
2010 CL19
Nov 25
37.6 LD
1.3 km
2013 NJ
Nov 26
2.5 LD
190 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.
  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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