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Solar wind
speed: 360.0 km/sec
density: 1.6 protons/cm3
explanation | more data
Updated: Today at 2347 UT
X-ray Solar Flares
6-hr max: B3
2228 UT Jul23
24-hr: B6
0244 UT Jul23
explanation | more data
Updated: Today at: 2300 UT
Daily Sun: 23 July 13
None of these sunspots is actively flaring. Solar activity is very low. Credit: SDO/HMI
Sunspot number: 53
What is the sunspot number?
Updated 23 Jul 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 Jul 2013

The Radio Sun
10.7 cm flux: 110 sfu
explanation | more data
Updated 23 Jul 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: 3.2 nT
Bz: 2.2 nT south
explanation | more data
Updated: Today at 2347 UT
Coronal Holes: 23 Jul 13
Solar wind flowing from the indicated coronal hole should reach Earth on July 25-26. 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: 07-23-2013 12:55:02
NOAA Forecasts
Updated at: 2013 Jul 23 2200 UTC
0-24 hr
24-48 hr
10 %
10 %
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 Jul 23 2200 UTC
0-24 hr
24-48 hr
10 %
10 %
01 %
01 %
01 %
01 %
High latitudes
0-24 hr
24-48 hr
15 %
15 %
20 %
20 %
10 %
10 %
Tuesday, Jul. 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

VERY QUIET SUN: Solar activity has shifted from low to very low. None of the sunspots on the Earthside of the sun is actively flaring. NOAA forecasters expect this situation to continue for the next 24 hours. They estimate a slim 10% chance of M-class flares and no more than a 1% chance of X-flares on July 23rd. Solar flare alerts: text, voice.

PALE BLUE DOT: Last Friday, NASA's Cassini spacecraft photographed Earth through the rings of Saturn. Our planet has been photographed twice before from the outer solar system, but this is the first time it has been recorded in natural color, as human eyes would see it. In the image, just released by NASA, Earth is a pale blue dot:

Normally, distant spacecraft cannot photograph Earth because Earth is so close to the sun. Glare prevents imaging. Cassini took advantage of a rare eclipse of the sun by Saturn itself. With the sun blocked by the body of the ringed planet, Earth became visible to Cassini's cameras.

The picture of Earth is only one footprint in a mosaic of 33 footprints covering the entire Saturn ring system. "Seeing the whole mosaic of the backlit rings when it is put together will be incredible," says Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory. Researchers are working on the ensemble now, and they expect it to be ready in a few weeks.

Realtime Space Weather Photo Gallery

MAMMATUS OVER MICHIGAN: Yesterday, a rain squall blew through Iron Mountain, Michigan, and left some unusual clouds in its wake. Laura Tappy snapped this picture:

"There was heavy rain for about five minutes," describes Tappy. "When it ended, the sky turned an eerie yellow color and these mammatus clouds appeared."

Named for their resemblance to a cow's underbelly, mammatus clouds sometimes appear at the end of severe thunderstorms when the thundercloud is breaking up. Researchers have called them an "intriguing enigma," because no one knows exactly how and why they form. The clouds are fairly common but often go unnoticed because potential observers have been chased indoors by the rain. If you are one of them, go back outside when the downpour stops; you could witness a beautiful mystery in the sky.

Realtime Space Weather Photo Gallery

PETUNIAS AT THE EDGE OF SPACE: The students of Earth to Sky Calculus have recovered the petunias they sent to the stratosphere last Friday. The flowers left Earth July 19th onboard a helium research balloon, ascended to 110,570 feet, then parachuted back to Earth on the same day. These four screenshots, culled from more than 2 hours of high-definition video, summarizes what happened:

(1) The flowers were pink and alert when they left Earth. (2) An hour later, in the stratosphere, the flowers appear limp and wilted, but they were not. Actually, the flowers were frozen. The petals were bent downward by onrushing wind during the ascent, and they froze in place as the petunias passed through the tropopause where the temperature was -63 C. (3) You can see that the flowers were frozen stiff because when the balloon exploded, they did not move at all. (4) Finally, as the payload parachuted back to Earth the flowers thawed and turned deep purple.

The petunias were just one of several experiments flown to the stratosphere on July 19th during Cassini's historic photo-shoot of Earth through the rings of Saturn. Other items on board were selected competitively from more than 1056 entries suggested by readers. First place winners of the competition received free telescopes from Explore Scientific.

For updates about data from this flight, please follow the Earth to Sky Calculus Twitter feed.

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 July 23, 2013 there were 1397 potentially hazardous asteroids.
Recent & Upcoming Earth-asteroid encounters:
Miss Distance
2006 BL8
Jul 26
9.3 LD
48 m
2003 DZ15
Jul 30
9.1 LD
152 m
2005 WK4
Aug 9
8.1 LD
420 m
1999 CF9
Aug 23
24.7 LD
1.1 km
2002 JR9
Aug 31
63.5 LD
1.4 km
1992 SL
Sep 23
70 LD
1.1 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 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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