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Solar wind
speed: 413.6 km/sec
density: 5.2 protons/cm3
explanation | more data
Updated: Today at 2347 UT
X-ray Solar Flares
6-hr max: B9
1843 UT Sep23
24-hr: C1
1536 UT Sep23
explanation | more data
Updated: Today at: 2300 UT
Daily Sun: 23 Sept 14
Sunspot AR2172 is quiet yet poses a growing threat for strong flares. Credit: SDO/HMI
Sunspot number: 87
What is the sunspot number?
Updated 23 Sep 2014

Spotless Days
Current Stretch: 0 days
2014 total: 1 day (<1%)
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%)

Update 23
Sep 2014

The Radio Sun
10.7 cm flux: 130 sfu
explanation | more data
Updated 23 Sep 2014

Current Auroral Oval:
Switch to: Europe, USA, New Zealand, Antarctica
Planetary K-index
Now: Kp= 3 quiet
24-hr max: Kp= 3
explanation | more data
Interplanetary Mag. Field
Btotal: 7.3 nT
Bz: 3.9 nT south
explanation | more data
Updated: Today at 2347 UT
Coronal Holes: 22 Sep 14
A stream of solar wind flowing from the indicated coronal hole could reach Earth on Sept. 26-27. Credit: SDO/AIA. posts 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: 09-02-2014 12:55:12
NOAA Forecasts
Updated at: 2014 Sep 23 2200 UTC
0-24 hr
24-48 hr
30 %
30 %
05 %
05 %
Geomagnetic Storms:
Probabilities for significant disturbances in Earth's magnetic field are given for three activity levels: active, minor storm, severe storm
Updated at: 2014 Sep 23 2200 UTC
0-24 hr
24-48 hr
25 %
20 %
10 %
05 %
01 %
01 %
High latitudes
0-24 hr
24-48 hr
15 %
15 %
30 %
25 %
40 %
30 %
Tuesday, Sep. 23, 2014
What's up in space

When is the best time to see auroras? Where is the best place to go? And how do you photograph them? These questions and more are answered in a new book, Northern Lights - a Guide, by Pal Brekke & Fredrik Broms.

Northern Lights - a Guide

AUTUMNAL EQUINOX: Today, Sept. 23rd at 0229 UT, the sun crossed the celestial equator heading south. The crossing marks the beginning of fall in the northern hemisphere--a.k.a. the autumnal equinox. Equinox means equal night. With the sun near the celestial equator, we experience equal amounts of daylight and darkness, 12 hours of each. Aurora alerts: text, voice

AURORA SEASON: The beginning of northern autumn is good news for sky watchers: It's also the beginning of aurora season. For reasons researchers do not fully understand, geomagnetic storms happen most often around the time of equinoxes. Last night, just as the sun was crossing the celestial equator, auroras exploded through the clouds over Sortland, Norway:

"There were no auroras in the forecast," says photographer Frank Olsen, "but I decided to head out anyway. As soon as it was dark enough there was quite a show."

Olsen's story is typical of autumn in the Arctic. The forecast calls for no auroras, but a gentle gust of solar wind produces some anyway. Mindful of the season, NOAA forecasters estimate a 40% chance of polar geomagnetic storms on Sept. 23rd as a minor stream of solar wind blows around Earth. Aurora alerts: text, voice

Realtime Aurora Photo Gallery

BROODING GIANT: Solar activity is low. However, new sunspot AR2172 threatens to break the quiet. Karzaman Ahmad photographed the behemoth active region on Sept. 22nd from the Langkawi National Observatory in Maylasia:

The sunspot's primary dark cores are nearly as wide as Earth, and the entire group stretches more than 80,000 km from end to end. These dimensions make AR2172 an easy target for small solar telescopes. "I took the picture using an 11-inch telescope," says Ahmad.

Yesterday, for a while, the sunspot's magnetic field displayed an unstable mixture of polarities that harbored energy for strong explosions. Now the threat has subsided. As the situation shifts back and forth, NOAA forcasters estimate a 30% chance of M-class flares and a 5% chance of X-flares on Sept. 23rd. Solar flare alerts: text, voice

Realtime Space Weather Photo Gallery

STUDENTS MEASURE 'FORBUSH DECREASE': On Sept. 12th, a CME hit Earth's magnetic field, igniting the most intense geomagnetic storm of the year. The students of Earth to Sky Calculus quickly launched a helium balloon to the stratosphere to see what effect the storm was having on Earth's upper atmosphere. They expected to measure more radiation than usual. Instead, they measured less. This plot shows a sharp drop in high-energy radiation on Sept. 12th compared to previous flights in May, June, and August:

What caused this counterintuitive drop? Answer: When the CME swept past Earth, it swept aside many of the cosmic rays that normally surround our planet. The effect is called a "Forbush Decrease," named after physicist Scott E. Forbush who first described it in the 20th century.

Wherever CMEs go, cosmic rays are deflected by magnetic fields inside the CME. Forbush decreases have been observed on Earth and in Earth orbit onboard Mir and the ISS. The Pioneer 10 and 11 and Voyager 1 and 2 spacecraft have experienced them, too, beyond the orbit of Neptune. Now high school students have detected a Forbush Decrease in the stratosphere using little more than an insulated lunchbox and a helium balloon.

The balloon's lunchbox-payload is shown here suspended more than 100,000 feet above the Sierras of central California:

Inside the payload, there was an ionizing radiation sensor (energy range: 10.0 KeV to 20.0 MeV), a cryogenic thermometer, multiple GPS altimeters and trackers, and three cameras. During the 2.5 hour flight, the buoy collected more than 50 gigabytes of video and science data ranging in altitude from 8500 ft to 113,700 ft above sea level. The analysis is still underway.

The students wish to thank Caisson Biotech LLC for sponsoring this flight. Note their logo on the upper right corner of the payload!

Readers, if you would like to sponsor an upcoming balloon launch and have your logo flown to the edge of space, please contact Dr. Tony Phillips to make arrangements. The cost of sponsorship is $500. Sponsors receive a complete video of the flight along with advertising exposure on

Realtime Space Weather Photo Gallery

Realtime Comet Photo Gallery

  All Sky Fireball Network

Every night, a network of NASA all-sky cameras scans the skies above the United States for meteoritic fireballs. Automated software maintained by NASA's Meteoroid Environment Office calculates their orbits, velocity, penetration depth in Earth's atmosphere and many other characteristics. Daily results are presented here on

On Sep. 23, 2014, the network reported 32 fireballs.
(32 sporadics)

In this diagram of the inner solar system, all of the fireball orbits intersect at a single point--Earth. The orbits are color-coded by velocity, from slow (red) to fast (blue). [Larger image] [movies]

  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, 2014 there were potentially hazardous asteroids.
Recent & Upcoming Earth-asteroid encounters:
Miss Distance
2006 GQ2
Sep 19
65.9 LD
1.1 km
2014 RW18
Sep 20
6.3 LD
28 m
2014 SG1
Sep 20
0.2 LD
7 m
2014 SN142
Sep 23
1.1 LD
10 m
2009 FG19
Sep 26
34.6 LD
1.1 km
2014 SS143
Sep 29
3.6 LD
16 m
2014 NE52
Sep 30
61.2 LD
1.1 km
2001 EA16
Oct 7
35.5 LD
1.9 km
2011 TB4
Oct 9
5.8 LD
34 m
2010 FV9
Oct 11
8.7 LD
36 m
2003 UC20
Oct 31
52.4 LD
1.0 km
2004 JN13
Nov 18
52.4 LD
4.1 km
1998 SS49
Nov 18
73.9 LD
3.2 km
2005 UH3
Nov 22
44.4 LD
1.3 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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