You are viewing the page for Jul. 23, 2011
  Select another date:
<<back forward>> -- News and information about meteor showers, solar flares, auroras, and near-Earth asteroids
Solar wind
speed: 500.7 km/sec
density: 1.6 protons/cm3
explanation | more data
Updated: Today at 2341 UT
X-ray Solar Flares
6-hr max: B2
1722 UT Jul23
24-hr: B5
1449 UT Jul23
explanation | more data
Updated: Today at: 2300 UT
Daily Sun: 23 Jul 11
None of these sunspots poses an immediate threat for strong flares. Solar activity remains low. Credit: SDO/HMI
Sunspot number: 54
What is the sunspot number?
Updated 22 Jul 2011

Spotless Days
Current Stretch: 0 days
2011 total: 1 day (<1%)
2010 total: 51 days (14%)
2009 total: 260 days (71%)
Since 2004: 820 days
Typical Solar Min: 486 days

Updated 22 Jul 2011

The Radio Sun
10.7 cm flux: 92 sfu
explanation | more data
Updated 22 Jul 2011

Current Auroral Oval:
Switch to: Europe, USA, New Zealand, Antarctica
Planetary K-index
Now: Kp= 2 quiet
24-hr max: Kp= 3
explanation | more data
Interplanetary Mag. Field
Btotal: 2.4 nT
Bz: 1.1 nT north
explanation | more data
Updated: Today at 2344 UT
Coronal Holes: 23 Jul 11
A new coronal hole is emerging over the sun's NE limb. Credit: SDO/AIA.
NOAA Forecasts
Updated at: 2011 Jul 23 2200 UTC
0-24 hr
24-48 hr
01 %
01 %
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: 2011 Jul 23 2200 UTC
0-24 hr
24-48 hr
10 %
10 %
05 %
05 %
01 %
01 %
High latitudes
0-24 hr
24-48 hr
10 %
10 %
05 %
05 %
01 %
01 %
Saturday, Jul. 23, 2011
What's up in space

Turn your cell phone into a field-tested satellite tracker. Works for Android and iPhone.

Satellite flybys

ELECTRON WARNING: Analysts at the GSFC Space Weather Lab report elevated levels of energetic electrons around Earth. ("GOES 13 > 0.8 MeV integral electron flux is above 105 pfu." ) This is caused by the high-speed solar stream now blowing around our planet. Spacecraft with orbits passing through or in the vicinity of the Earth's outer radiation belt could be affected by these charged particles.

COLORFUL SOUTHERN LIGHTS: Oh to be in Antarctica. The skies over the polar continent have filled with colorful lights in response to a solar wind stream now buffeting Earth's magnetic field. J. Dana Hrubes sends this snapshot from the Amundsen-Scott research station at the geographic South Pole:

"The auroras last night were just amazing--some of the best we've seen this winter," says Hrubes. The frosty scaffolding in the image is attached to the South Pole Telescope (SPoT), a millimeter wave radio telescope used to study the early evolution of the Universe. Hrubes operates SPoT during Antarctica's winter months. "It's a little cold," he allows, "but the view is out of this world."

High-latitude sky watchers should remain alert for auroras as the solar wind continues to blow.

LAST RE-ENTRY: On July 21st, the crew of the International Space Station photographed an event that will never be repeated: the re-entry of a space shuttle. Marking the end of NASA's 30-year shuttle program, Atlantis dove Earthward in a fiery arc that only six lucky space travelers could see from above:

The green band of light in the background is called "airglow." Airglow is a luminous bubble that surounds our entire planet, decorating the top of the atmosphere with aurora-like color. Although airglow resembles the aurora borealis, its underlying physics is different. Airglow is caused by an assortment of chemical reactions in the upper atmosphere driven mainly by solar ultraviolet radiation; auroras, on the other hand, are prompted by gusts of solar wind.

More pictures from the last flight of Atlantis may be found here.

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

June 2011 Aurora Gallery
[Aurora alerts: text, voice] [previous Junes: 2010, 2008, 2001]

  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, 2011 there were 1237 potentially hazardous asteroids.
Recent & Upcoming Earth-asteroid encounters:
Miss Distance
2003 YS117
Jul 14
73.9 LD
1.0 km
2007 DD
Jul 23
9.3 LD
31 m
2003 BK47
Jul 26
77.6 LD
1.1 km
2009 AV
Aug 22
49.7 LD
1.1 km
2003 QC10
Sep 18
50 LD
1.2 km
2004 SV55
Sep 19
67.5 LD
1.2 km
2007 TD
Sep 23
3.8 LD
58 m
2002 AG29
Oct 9
77.1 LD
1.0 km
2000 OJ8
Oct 13
49.8 LD
2.5 km
2009 TM8
Oct 17
1.1 LD
8 m
2011 FZ2
Nov 7
75.9 LD
1.6 km
2005 YU55
Nov 8
0.8 LD
175 m
1994 CK1
Nov 16
68.8 LD
1.5 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
Science Central
Conquest Graphics
  for out-of-this-world printing and graphics
Trade Show Displays
  more links...
©2010 All rights reserved. This site is penned daily by Dr. Tony Phillips.
©2013 All rights reserved.