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Solar wind
speed: 479.0 km/sec
density: 3.0 protons/cm3
explanation | more data
Updated: Today at 2349 UT
X-ray Solar Flares
6-hr max: C1
2141 UT Aug20
24-hr: C3
0527 UT Aug20
explanation | more data
Updated: Today at: 2300 UT
Daily Sun: 20 Aug 15
Sunspot AR2403 poses a growing threat for solar flares. However, solar activity remains low. Credit: SDO/HMI

Sunspot number: 36
What is the sunspot number?
Updated 20 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 20 Aug 2015

The Radio Sun
10.7 cm flux: 98 sfu
explanation | more data
Updated 20 Aug 2015

Current Auroral Oval:
Switch to: Europe, USA, New Zealand, Antarctica
Credit: NOAA/Ovation
Planetary K-index
Now: Kp= 3 quiet
24-hr max: Kp= 4
explanation | more data
Interplanetary Mag. Field
Btotal: 6.1 nT
Bz: 2.4 nT north
explanation | more data
Updated: Today at 2349 UT
Coronal Holes: 20 Aug 15

Solar wind flowing from the indicated coronal hole could reach Earth on Aug. 21-22. Credit: SDO/AIA.
Noctilucent Clouds The northern season for NLCs is underway. NASA's AIM spacecraft spotted the first noctilucent clouds over the Arctic Circle on May 19th.
Switch view: Europe, USA, Asia, Polar
Updated at: 08-20-2015 16:55:04
NOAA Forecasts
Updated at: 2015 Aug 20 2200 UTC
0-24 hr
24-48 hr
15 %
15 %
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: 2015 Aug 20 2200 UTC
0-24 hr
24-48 hr
30 %
25 %
05 %
05 %
01 %
01 %
High latitudes
0-24 hr
24-48 hr
15 %
20 %
35 %
35 %
40 %
30 %
Thursday, Aug. 20, 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

INCREASING CHANCE OF FLARES: Solar activity is still low. However, it could be set to increase with the emergence of a new sunspot, AR2403. The active region in the sun's southern hemisphere has doubled in size since yesterday and is starting to crackle with C-class solar flares. Solar flare alerts: text or voice

RADIO STORM ON JUPITER: Two days ago, amateur astronomer Thomas Ashcraft of New Mexico pointed his radio telescope at the sun, something he does on a regular basis to monitor solar activity. As if on cue, the loud speaker erupted in a series of hisses and crackles. However, the source of the static wasn't the sun--it was Jupiter. "I detected a powerful radio storm on Jupiter," he says. Click on the image to play the 'rat-a-tat-tat' sounds of the giant planet:

"Jupiter was overhead at noon local time and right in the sweet spot of my radio telescope," says Ashcraft. "The radio storm lasted a full two hours."

Jupiter is a powerful source of shortwave radio bursts. They come from natural radio lasers in the giant planet's magnetosphere. Electrical currents flowing between Jupiter's upper atmosphere and the volcanic moon Io can boost these emissions to power levels easily detected by ham radio antennas on Earth. That's what happened on August 18th. Each of the sharp crackles in the recording coresponds to a single radio laser beam sweeping past Earth as Jupiter rotates.

Ashcraft notes that Jupiter is passing behind the sun this week, "so Jupiter is about as far away from Earth as it ever gets. I detected these bursts from a distance of 955,022,185 kilometers."

To learn more about radio storms on Jupiter, and how you can observe them yourself, visit NASA's RadioJove web site.

Realtime Space Weather Photo Gallery

SPRITES AND TROLLS AT THE EDGE OF SPACE: We all know what comes out of the bottom of thunderclouds: lightning. But rarely do we see what comes out of the top. On August 10th, astronauts onboard the International Space Station were perfectly positioned to observe red sprites dancing atop a cluster of storms in Mexico. They snapped this incredible photo:

This shows just how high sprites can go. The photo shows their red forms reaching all the way from the thunderstorm below to a layer of green airglow some 100 km above Earth's surface. This means sprites touch the edge of space, alongside auroras, meteors and noctilucent clouds. They are a true space weather phenomenon.

A few minutes after the astronauts saw the sprites, they spotted a related creature--a "Troll." It jumped up to the left of the sprites:

"Trolls are also known as 'secondary transient luminous events," explains Oscar van der Velde, a member of the Lightning Research Group at the Universitat Politècnica de Catalunya. "They are occasionally observed alongside big clusters of sprites, and they can reach 40-60 km high."

Van der Velde says that sprites can actually pull Earth's ionosphere down toward the thunderstorm. When the gap shrinks, and the local electric field intensifies, Trolls appear.

You don't have to be onboard a spaceship to see these exotic forms of lightning. "Sprite chasers" regularly photograph the upward bolts from their own homes. Van der Velde has photographed Trolls from ground-level, too. "I recorded these trolls last October over a storm over the Mediterranean Sea west of Sardinia and Corsica," he says. Browse the sprite gallery for more examples.

Realtime Sprite Photo Gallery

A RARE FORM OF AURORAS: A surprisingly strong G3-class geomagnetic storm erupted on Aug. 15th when a CME hit Earth's magnetic field. Two nights later, as the storm was subsiding, midnight sky watchers in North America witnessed a rare and beautiful form of aurora--a "proton arc." Paul Zizka photographed the phenomenon on Aug. 17th from Banff, Alberta:

"It was incredible," says Zizka. "The whitish pillar remained nearly stationary for over 30 minutes--enough time for a self-portrait."

In Val Marie, Saskatchewan, photographer Sherri Grant saw a purple proton arc cutting across the Milky Way. And in Oroville, Washington, at the Table Mountain Star Party, campers witnessed at least two more arcs.

Ordinary auroras are caused by electrons, which rain down on Earth's atmosphere from above. Atoms of oxygen and nitrogen, excited by the pitter-patter of electrons, form dynamic curtains of light. Protons have a different effect. For reasons not fully understood, protons normally trapped in our planet's ring current sometimes rain down on Earth's atmosphere during geomagnetic storms. En route, they excite a type of plasma wave called "EMIC"--short for electromagnetic ion cyclotron waves. The result is not a curtain, but rather a tight arc of light as shown above.

Many of the photographers who witnessed proton arcs on Aug. 17th have been observing auroras for years, yet they had never seen this phenomenon before. Geomagnetic storms still have the capacity to surprise! Aurora alerts: text or voice

Realtime Aurora 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. 20, 2015, the network reported 32 fireballs.
(29 sporadics, 2 Perseids, 1 kappa Cygnid)

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 20, 2015 there were potentially hazardous asteroids.
Recent & Upcoming Earth-asteroid encounters:
Miss Distance
2005 JF21
Aug 16
20.1 LD
1.6 km
2015 QK
Aug 19
4.7 LD
25 m
2015 PT227
Aug 29
9.7 LD
71 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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