You are viewing the page for Sep. 23, 2011
  Select another date:
<<back forward>>
SpaceWeather.com -- News and information about meteor showers, solar flares, auroras, and near-Earth asteroids
 
Solar wind
speed: 373.4 km/sec
density: 0.3 protons/cm3
explanation | more data
Updated: Today at 2344 UT
X-ray Solar Flares
6-hr max: M1
2217 UT Sep23
24-hr: M1
2217 UT Sep23
explanation | more data
Updated: Today at: 2300 UT
Daily Sun: 23 Sep 11
Sunspot 1302 poses a threat for X-class solar flares. Credit: SDO/HMI

more images: from David Maidment of Sohar, Oman; from Enrico Colzani et al of Sormano Astronomical Observatory, Italy: from Peter Paice of Belfast, Northern Ireland;
Sunspot number: 86
What is the sunspot number?
Updated 22 Sep 2011

Spotless Days
Current Stretch: 0 days
2011 total: 2 days (<1%)
2010 total: 51 days (14%)
2009 total: 260 days (71%)
Since 2004: 821 days
Typical Solar Min: 486 days

Updated 22 Sep 2011


The Radio Sun
10.7 cm flux: 151 sfu
explanation | more data
Updated 22 Sep 2011

Current Auroral Oval:
Switch to: Europe, USA, New Zealand, Antarctica
Credit: NOAA/POES
Planetary K-index
Now: Kp= 1 quiet
24-hr max: Kp= 1
quiet
explanation | more data
Interplanetary Mag. Field
Btotal: 2.8 nT
Bz: 2.7 nT north
explanation | more data
Updated: Today at 2346 UT
Coronal Holes: 23 Sep 11
There are no large coronal holes on the Earth-facing side of the sun. Credit: SDO/AIA.
SPACE WEATHER
NOAA Forecasts
Updated at: 2011 Sep 23 2200 UTC
FLARE
0-24 hr
24-48 hr
CLASS M
70 %
70 %
CLASS X
20 %
20 %
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 Sep 23 2200 UTC
Mid-latitudes
0-24 hr
24-48 hr
ACTIVE
05 %
10 %
MINOR
01 %
01 %
SEVERE
01 %
01 %
High latitudes
0-24 hr
24-48 hr
ACTIVE
10 %
15 %
MINOR
01 %
01 %
SEVERE
01 %
01 %
 
Friday, Sep. 23, 2011
What's up in space
 

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

 
Satellite flybys

UARS RE-ENTRY UPDATE: NASA's UARS satellite is making its last orbits around Earth. Orbital elements published today by the US Strategic Command suggest that re-entry could occur during the early hours of Saturday morning. "For now, it looks like 00:00 - 04:00 UTC on Sept. 24," says satellite tracking expert Ted Molczan, "but it could well happen even later. UARS will pass over North America and Europe several times during this period, but it will spend most of its time over oceans and sparsely populated land." Stay tuned for updates and meanwhile keep an eye out for the doomed satellite. [latest NASA statement]

The Federal Aviation Administration has issued the following Notice to Airmen (NOTAM): "Aircraft are advised that a potential haard may occur due to reentry of satellite UARS into Earth's atmosphere. FAA is working with the Department of Defense and NASA to ensure the most current re-entry information is provided to operators as quickly as possible. Further NOTAMS will be issued if specific information becomes available indicating a United States airspace impact. It is critical that all pilots/flight crew members report any fallinf space debris to the appropriate ATC facility. The Domestic Events Network telephone 202-493-5107 is the FAA coordination facility. CREATED: 23 SEP 18:33 2011"

EQUINOX SUNRISE: The seasons changed this morning at 5:05 a.m. EDT when the Sun crossed the celestial equator heading south. Fall began in the Northern Hemisphere, spring in the Southern Hemisphere. Geoffrey Wyatt of Sydney, Australia, woke up early to watch the equinox sun rise over Watson's Bay:

"This is how the first day of spring began in Australia," says Wyatt. "Recent fires in the Sydney area have contributed to redder than usual sunrises and sunsets. Temperature gradiants over the water produced the added bonus of a miraged sun."

Happy Equinox!

more images: from Monika Landy-Gyebnar of Balatonfured, Hungary

AURORAS UNDERFOOT: Solar activity is picking up, and no one has a better view of its effect on Earth than the crew of the International Space Station. During a geomagnetic storm on Sept. 17th, astronauts recorded a must-see movie of auroras dancing underfoot:


Taken over the southern Indian Ocean, the movie spans a 23-min period from 17:22:27 to 17:45:12 GMT on Sept. 17.

Note how the underbelly of the space station glows green from the reflected light of the auroras below. Also, in the distance, Sirius the dog star and Orion the Hunter can be seen rising feet-first into the night sky.

The storm, which registered a moderate 6 on the 0-to-9 K-index scale of geomagnetic disturbances, was caused by a coronal mass ejection (CME) hitting Earth's magnetic field. It was just a glancing blow, but with CMEs that is often enough to spark bright auroras over both ends of Earth. The space station was flying over the southern hemisphere at the time of the display. Observers in the northern hemisphere saw it too.

A similar storm could be in the offing this week. Another CME is heading toward Earth, and it appears likely to deliver a glancing blow on Sept. 22nd around 23:00 UT. Sky watchers above and below should be alert for auroras. Aurora alerts: text, voice.

September 2011 Aurora Gallery
[previous Septembers: 2010, 2009, 2008, 2007, 2006, 2005, 2004]

MAJOR X-FLARE + CME: Yesterday, Earth-orbiting satellites detected a long-duration X1.4-class solar flare coming from sunspot 1302 on the sun's eastern limb. The blast, which peaked at 1100 UT on Sept. 22nd, produced a significant coronal mass ejection (CME). Using data from the SOHO-STEREO fleet of spacecraft, analysts at the Goddard Space Weather Lab have modeled the trajectory of the CME and concluded that the body of the cloud will not hit Earth. A minor glancing encounter with the outskirts of the CME is, however, possible on Sept. 25th. [CME: movie, forecast track]

X-flares of Solar Cycle 24: There have been only a half-dozen X-flares since the beginning of new Solar Cycle 24. Here is a complete list so far, all in 2011: Feb. 15 (X2), March 9 (X1), Aug. 9 (X7), Sept. 6 (X2), Sept. 7 (X2), Sept. 22 (X1). Before these six, the previous X-flare occured on Dec.14, 2006, (X1) during old Solar Cycle 23.

  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, 2011 there were 1244 potentially hazardous asteroids.
Recent & Upcoming Earth-asteroid encounters:
Asteroid
Date(UT)
Miss Distance
Mag.
Size
2003 QC10
Sep 18
50 LD
--
1.2 km
2004 SV55
Sep 19
67.5 LD
--
1.2 km
2007 TD
Sep 22
6.2 LD
--
58 m
2011 SO5
Sep 29
5.6 LD
--
35 m
2002 AG29
Oct 9
77.1 LD
--
1.0 km
2011 SS25
Oct 13
70.2 LD
--
1.2 km
2000 OJ8
Oct 13
49.8 LD
--
2.4 km
2009 TM8
Oct 17
0.9 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
1996 FG3
Nov 23
39.5 LD
--
1.1 km
2003 WM7
Dec 9
47.6 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.
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
Science Central
 
Conquest Graphics
  for out-of-this-world printing and graphics
Trade Show Displays
   
  more links...
©2010 Spaceweather.com. All rights reserved. This site is penned daily by Dr. Tony Phillips.
©2013 Spaceweather.com. All rights reserved.