MINOR STORM FORECAST: NOAA forecasters estimate a 75% chance of polar geomagnetic storms on Aug. 25th in response to an expected CME impact. High-latitude sky watchers should be alert for auroras. Aurora alerts: text, voice.
TWILIGHT AURORAS: It's that time of year. As the midnight sun wanes, auroras are reappearing in Arctic skies. Sky watchers are seeing a mix of colors, twilight-blue + aurora green, that is unique to the end of northern summer:
"This was my first glimpse of Northern Lights this season," says photographer Stian Rekdal, who took the picture on Aug. 23rd from Reine, Nordland, Norway.
More twilight auroras are in the offing. NOAA forecasters estimate a 60% to 75% chance of polar geomagnetic storms this weekend in response to an incoming CME.
ONE LESS COMET: Subtract one from the Solar System's total count of comets. Yesterday a small unnamed comet dove into the sun and completely evaporated. Click on the image to see the death plunge, animated:
The icy comet, R.I.P., was a member of the Kreutz family. Kreutz sungrazers are fragments from the breakup of a single giant comet many centuries ago. They are seen falling into the sun dozens of times a year. This particular sungrazer measured a few tens of meters in diameter, too small to survive a close approach with the sun.
A much larger sungrazer is on the way. Comet ISON (not a member of the Kreutz family, but a sungrazer nevertheless) will fly through the sun's atmosphere on Thanksgiving Day 2013. Unlike yesterday's tiny comet, Comet ISON is expected to survive its brush with death. The nucleus of ISON is probably wider than 0.5 kilometers, too big to completely evaporate during its transit of the sun's atmosphere. If optimistic estimates are correct, Comet ISON could emerge post-Thanksgiving as one of the brightest comets in many years.
First, however, Comet ISON is paying a visit to Mars on Oct. 1st, giving Mars rovers and satellites a sneak preview of a potentially-Great Comet. Watch this NASA video for details.
 |
Solar wind
speed: 410.8 km/sec
density: 0.9 protons/cm3
explanation | more data
Updated: Today at 1547 UT
|
X-ray Solar Flares
6-hr max: B5 1011 UT Aug25
24-hr: B7 0201 UT Aug25
explanation | more data
Updated: Today at: 1500 UT
|
|
Daily Sun: 25 Aug 13
|
|
None of these sunspots poses a threat for strong solar flares. Credit: SDO/HMI
|
|
Sunspot number: 101
What is the sunspot number?
Updated 25 Aug 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
Update 25 Aug 2013
The Radio Sun
10.7 cm flux: 117 sfu
explanation | more data
Updated 25 Aug 2013
|
|
Current Auroral Oval:
|
|
Switch to: Europe, USA, New Zealand, Antarctica
Credit: NOAA/POES
|
|
Planetary K-index
Now: Kp= 2 quiet
24-hr max: Kp= 3 quiet
explanation | more data
|
Interplanetary Mag. Field
Btotal: 3.9 nT
Bz: 1.8 nT south
explanation | more data
Updated: Today at 1547 UT
|
|
Coronal Holes: 25 Aug 13
|
|
Solar wind flowing from the indicated coronal hole should reach Earth on Aug. 27-28. Credit: SDO/AIA.
