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Solar wind
speed: 402.4 km/sec
density: 4.0 protons/cm3
explanation | more data
Updated: Today at 2347 UT
X-ray Solar Flares
6-hr max: B4
2040 UT Jul21
24-hr: C3
0844 UT Jul21
explanation | more data
Updated: Today at: 2300 UT
Daily Sun: 21 July 13
Sunspot AR1793 has a beta-gamma magnetic field that harbors energy for M-class solar flares. However, the sunspot is quiet. Credit: SDO/HMI
Sunspot number: 57
What is the sunspot number?
Updated 21 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

21 Jul 2013

The Radio Sun
10.7 cm flux: 113 sfu
explanation | more data
Updated 21 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: 5.1 nT
Bz: 2.3 nT north
explanation | more data
Updated: Today at 2347 UT
Coronal Holes: 21 Jul 13
Earth is inside a solar wind stream flowing from the indicated coronal hole. 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: 07-21-2013 11:55:02
NOAA Forecasts
Updated at: 2013 Jul 21 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 21 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 %
Sunday, Jul. 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

QUIET SUN: Solar activity is low. The biggest sunspot on the Earthside of the sun, AR1783, has been quiet for days even though it has a 'beta-gamma' magnetic field that harbors energy for M-class solar flares. NOAA forecasters estimate a slim 10% chance that AR1783 will break the quiet with an M-flare on July 21st. Solar flare alerts: text, voice.

BRIGHT NOCTILUCENT CLOUDS: Last night, sky watchers in Europe witnessed a bright display of noctilucent clouds. "Noctilucent clouds were shining from midnight to dawn," says Marek Nikodem, who sends this picture from ┼╗nin Lake near Szubin, Poland:

Nikodem is a veteran photographer of noctilucent clouds. "It was the most beautiful display of NLCs [I've seen] in July."

Noctilucent clouds are an early-summer phenomenon. Often, they begin to wane in late July, but this July the clouds are shining as brightly as ever as August approaches. This fits in with the emerging picture of 2013 as an unusually good year for NLCs.

Moreover, this could be an unusually good century for NLCs. Long ago, the clouds were confined to the Arctic, but in recent years NLCs have been sighted as far south as Utah, Colorado, and Nebraska. They might spread even farther south in 2013. Observing tips: Look west 30 to 60 minutes after sunset when the sun has dipped 6o to 16o below the horizon. If you see luminous blue-white tendrils spreading across the sky, you've probably spotted a noctilucent cloud.

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

PETUNIAS FALL FROM THE EDGE OF SPACE: On Friday, July 19th, Caleb Smith was hiking along the John Muir Trail in California's Sierra Nevada mountains when something unprecedented happened. A vase of petunias parachuted out of the sky. "They landed about 50 feet away from me," he reports. The flowers were returning from the stratosphere, where the students of Earth to Sky Calculus had sent them hours earlier to honor Cassini's historic photography of Earth through the rings of Saturn. Scroll past this pre-launch picture of the petunias to learn more about the mission:

The balloon was launched to photobomb Cassini's picture of Earth from the highest possible altitude. In addition to the petunias, the payload contained three scientific experiments, a copy of the Hitchhikers Guide to the Galaxy, and a Galileo Bobblehead. The 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.

The petunias were a bouquet for the ringed planet. It honors Saturn's ancient mythology as a god of agriculture and also makes reference to the Hitchhikers Guide to the Galaxy. Fans of Douglas Adams will understand their significance!

In addition to the items aimed at Saturn, the balloon also carried a space weather experiment. A device combining a GPS altimeter and cryogenic thermometer was sent aloft to measure the height of the tropopause, the coldest layer of Earth's atmosphere. The students who launched the balloon want to see if this changes in response to solar flares and radiation storms.

Stay tuned for more information about the balloon's recovery. Updates are available on Twitter.

Realtime Space Weather Photo Gallery

Realtime Aurora Photo Gallery

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 21, 2013 there were 1397 potentially hazardous asteroids.
Recent & Upcoming Earth-asteroid encounters:
Miss Distance
2001 PJ9
Jul 17
29.2 LD
1.1 km
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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