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Solar wind
speed: 358.0 km/sec
density: 2.6 protons/cm3
explanation | more data
Updated: Today at 2350 UT
X-ray Solar Flares
6-hr max: B3
1940 UT Aug31
24-hr: C2
0522 UT Aug31
explanation | more data
Updated: Today at: 2300 UT
Daily Sun: 31 Aug 15
With the departure of huge sunspot AR2403, the Earth-facing side of the sun is almost blank.. Credit: SDO/HMI

Sunspot number: 50
What is the sunspot number?
Updated 31 Aug 2015

Spotless Days
Current Stretch: 0 days
2015 total: 0 days (0%)

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%)

Updated 31 Aug 2015

The Radio Sun
10.7 cm flux: 92 sfu
explanation | more data
Updated 31 Aug 2015

Current Auroral Oval:
Switch to: Europe, USA, New Zealand, Antarctica
Credit: NOAA/Ovation
Planetary K-index
Now: Kp= 2 quiet
24-hr max: Kp= 2
explanation | more data
Interplanetary Mag. Field
Btotal: 4.3 nT
Bz: 0.9 nT north
explanation | more data
Updated: Today at 2350 UT
Coronal Holes: 31 Aug 15

A stream of solar wind flowing from the indicated coronal hole should reach Earth on or about Sept. 3rd. Credit: SDO/AIA.
Noctilucent Clouds The northern season for NLCs is underway--but not for much longer. According to NASA's AIM spacecraft, noctilucent clouds are waning as August comes to a close.
Switch view: Europe, USA, Asia, Polar
Updated at: 08-31-2015 06:00:00
NOAA Forecasts
Updated at: 2015 Aug 31 2200 UTC
0-24 hr
24-48 hr
05 %
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: 2015 Aug 31 2200 UTC
0-24 hr
24-48 hr
45 %
45 %
25 %
25 %
05 %
05 %
High latitudes
0-24 hr
24-48 hr
10 %
10 %
25 %
25 %
65 %
70 %
Monday, Aug. 31, 2015
What's up in space

Learn to photograph Northern Lights like a pro. Sign up for Peter Rosen's Aurora Photo Courses in Abisko National Park, winner of the TripAdvisor Certificate of Excellence Award 2015.

Lapland tours

NOCTILUCENT CLOUDS VANISH: Summer is the season for noctilucent clouds (NLCs), and now that northern summer is coming to an end, so are the clouds. NASA's AIM spacecraft may have spotted the last wisp of electric blue over Greenland on Aug. 27th. Data from Aug. 28th show no NLCs around the Arctic Circle. If the deficit continues, attention will shift to the southern hemisphere where Antarctic noctilucent cloud season begins in November. Stay tuned for updates.

ALMOST-BLANK SUN: The sunspot number is plummeting, and the Earth-facing side of the sun is almost blank. Scan this image, taken on Sept. 1st by NASA's Solar Dynamics Observatory, to see how many dark cores you can find:

There are only a few tiny spots, circled here. Not one of them has the type of unstable magnetic field that harbors energy for strong flares. As a result, the sun's X-ray output is flatlining. NOAA forecasters estimate a 5% chance of M-flares and no more than a 1% chance of X-flares during the next 24 hours. Solar flare alerts: text or voice

Realtime Space Weather Photo Gallery

NORTHERN LIGHTS, NO PARKA REQUIRED: Arctic skies are dimming again after a rare burst of summer auroras. From Aug. 26th to 29th, Earth passed through a region of space where the interplanetary magnetic field (IMF) connected with our own magnetic field, opening a crack in Earth's magnetosphere. Solar wind poured in to fuel displays like this one over Anchorage, Alaska:

"The sky was full of lights," says Anthony Madden, who took the picture from Lake Hood Airport on Aug. 28th. "The best part was, it was warm enough that I did not need a parka."

The storms are subsiding now, but they could return on Sept. 2nd when Earth crosses through a fold in the heliospheric current sheet. This is called a "solar sector boundary crossing," and NOAA forecasters estimate a 70% chance of polar geomagnetic storms when it occurs. Aurora alerts: text or voice

Realtime Aurora Photo Gallery

THE EDGE OF THE SUN: Giant sunspot AR2403 has departed, leaving the face of the sun mostly blank. Amateur astronomer Sergio Castillo of Corona, CA, decided to look for something else to photograph. "My search didn't take long," he says, "because there are plenty of beautiful prominences on the solar limb." This is what he saw on Aug. 29th:

The massive structure is more than 30,000 km tall and 100,000 km wide. Planet Earth could fit through the central arch with room to spare. (Croquette, anyone?)

Prominences are plumes of hot plasma held aloft by magnetic fields on the sun. Typical prominences last a few days, until the underlying magnetic supports become unstable and collapse. This one has already been visible for several days, so a photogenic explosion could be in the offing. Amateur astronomers with solar telescopes and filters are encouraged to monitor developments.

THE SUN SWALLOWS A COMET: On Friday, Aug.28th, the sun swallowed a comet. The Solar and Heliospheric Observatory (SOHO) spotted the icy vistor from the outer solar system making a headlong plunge into our star. One comet went in; none came out. Click to play the movie:

Heated by the sun at point blank range, the comet's fragile ices vaporized, leaving at most a "rubble pile" of rock and gravel scattered along its sungrazing orbit. Any remains are invisible from Earth.

The comet, R.I.P., was probably a member of the Kreutz family. Kreutz sungrazers are fragments from the breakup of a single giant comet many centuries ago. They get their name from 19th century German astronomer Heinrich Kreutz, who studied them in detail. Several Kreutz fragments pass by the sun and disintegrate every day. Most, measuring less than a few meters across, are too small to see, but occasionally a bigger fragment like this one (~10 m to 50 m) attracts attention.

Because of their common parentage, sungrazers often come in clusters. For this reason, it wouldn't be surprising to find yet another one in the offing. Monitor Karl Battam's Sungrazing Comet twitter feed for more sightings.

Realtime Space Weather Photo Gallery

Realtime Sprite Photo Gallery

Realtime Venus Photo Gallery

Realtime NLC 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 Aug. 31, 2015, the network reported 17 fireballs.
(16 sporadics, 1 alpha Aurigid)

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 August 31, 2015 there were potentially hazardous asteroids.
Recent & Upcoming Earth-asteroid encounters:
Miss Distance
2015 QT3
Aug 28
4.2 LD
71 m
2015 PT227
Aug 29
9.7 LD
69 m
2004 BO41
Aug 31
57.3 LD
1.2 km
1991 CS
Sep 4
62.1 LD
1.4 km
2014 KS76
Sep 14
8.7 LD
22 m
2004 TR12
Sep 15
58.8 LD
1.0 km
2000 FL10
Oct 10
65.7 LD
1.9 km
2011 QD48
Oct 17
67.5 LD
1.0 km
2014 UR
Oct 18
3.8 LD
21 m
2011 SE97
Oct 18
12 LD
50 m
2001 UY4
Oct 21
58.2 LD
1.0 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
Columbia Northern High School
  Web-based high school science course with free enrollment
  more links...
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