QUIET SUN: Solar activity is low. NOAA forecasters say the chance of an M-class flare today is no more than 10%. An X-flare is even less likely: less than 1%. No flares are in the offing.
NOT AURORAS: For the past week, solar wind has been buffeting Earth's magnetic field, turning skies around the Artic Circle beautiful shades of green. But not every green sky is caused by the aurora borealis. On Friday night, for example, pilot Brian Whittaker was flying 34,000 feet over the Atlantic Ocean when he witnessed verdant hues caused by a completely different phenomenon--airglow. Here is the picture he took from the cockpit window:
"A dark and moonless night away from all lights allowed a great view of this textured patch of airglow," says Whittaker. "The illumination was faint, but it could be seen especially in contrast to the dark ocean abyss below!"
Although airglow resembles the aurora borealis, its underlying physics is different. Airglow is caused by an assortment of chemical reactions in the upper atmosphere. During the day, ultraviolet radiation from the sun ionizes atoms and breaks apart molecules. At night, the atoms and molecules recombine, emitting photons as they return to normal. This process produces an aurora-like glow visible on very dark nights.
Because the Moon is new on Sept. 15th, tonight is a good night to spy this phenomenon. Get away from city lights, if you can, and take a look!
Solar wind
speed: 395.1 km/sec
density: 1.2 protons/cm3
explanation | more data
Updated: Today at 1507 UT
X-ray Solar Flares
6-hr max: B2 0749 UT Sep16
24-hr: B3 0442 UT Sep16
explanation | more data
Updated: Today at: 1459 UT
Daily Sun: 16 Sep 12
Solar activity is low. None of these sunspots are actively flaring. Credit: SDO/HMI
Sunspot number: 53
What is the sunspot number?
Updated 16 Sep 2012
Spotless Days
Current Stretch: 0 days
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 16 Sep 2012
The Radio Sun
10.7 cm flux: 101 sfu
explanation | more data
Updated 16 Sep 2012
Current Auroral Oval:
Switch to: Europe, USA, New Zealand, Antarctica
Credit: NOAA/POES
Planetary K-index
Now: Kp= 2 quiet
24-hr max: Kp= 2 quiet
explanation | more data
Interplanetary Mag. Field
Btotal: 4.1 nT
Bz: 2.7 nT north
explanation | more data
Updated: Today at 1506 UT
Coronal Holes: 12 Sep 12
A pair of coronal holes is emerging over the sun's eastern limb. Credit: SDO/AIA.
