By Spaceweather.com, 08/22/2015
CHANCE OF WEEKEND STORMS: NOAA forecasters estimate a 40% chance of polar geomagnetic storms today, increasing to 70% by Aug. 23rd. These storms, if they occur, would be caused by a pair of solar wind streams now heading for Earth. High-latitude sky watchers should be alert for auroras this weekend. Aurora alerts:text or voice
X-FLARES IN THE OFFING? Since the day before yesterday, sunspot AR2403 has more than quadrupled in size. It is now more than 90,000 km wide and poses a threat for M-class solar flares. John Ashley photographed it through the smokey atmosphere of Kila, Montana, on Aug. 20th:
“One good thing about our forest fires is that the smoke makes it easier to see sunspots,” says Ashley. “The current grouping of sunspot AR 2403 is heading towards a central location [on the solar disk] and should offer excellent views in the days ahead.”
It might offer some excellent flares, too. Just this morning, Aug. 21st at 0220 UT, AR2304 unleashed the first M-flare in 45 days: movie. A flash of extreme UV radiation ionized the top of Earth’s atmosphere, causing a minor HF radio blackout over the western Pacific Ocean. This event could be the herald of more eruptions to come, so stay tuned. Solar flare alerts: text or voice
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 trollslast October over a storm over the Mediterranean Sea west of Sardinia and Corsica,” he says. Browse the sprite gallery for more examples.
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.
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 Spaceweather.com.
On Aug. 22, 2015, the network reported 22 fireballs.
(21 sporadics, 1 Southern delta Aquariid)
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 22, 2015 there were potentially hazardous asteroids.
Recent & Upcoming Earth-asteroid encounters:
Asteroid
Date(UT)
Miss Distance
Size
2015 QK
Aug 19
4.7 LD
25 m
2015 QH3
Aug 21
4.4 LD
18 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.
Current Conditions
Solar wind
speed: 397.6 km/sec
density: 1.2 protons/cm3
explanation | more data
Updated: Today at 1540 UT
X-ray Solar Flares
6-hr max: M2 1323 UT Aug22
24-hr: M2 1323 UT Aug22
explanation | more data
Updated: Today at: 1500 UT
Daily Sun: 22 Aug 15
Growing sunspot AR2403 has a beta-gamma-delta magnetic field that harbors energy for X-class solar flares. Credit: SDO/HMI
Sunspot number: 78
What is the sunspot number?
Updated 21 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 21 Aug 2015
The Radio Sun
10.7 cm flux: 103 sfu
explanation | more data
Updated 21 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= 3 quiet
explanation | more data
Interplanetary Mag. Field
Btotal: 3.9 nT
Bz: 0.8 nT north
explanation | more data
Updated: Today at 1540 UT
Coronal Holes: 21 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: 08-21-2015 18:55:03
NOAA Forecasts
Updated at: 2015 Aug 21 2200 UTC
FLARE
0-24 hr
24-48 hr
CLASS M
35 %
35 %
CLASS X
10 %
10 %
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 21 2200 UTC
Mid-latitudes
0-24 hr
24-48 hr
ACTIVE
10 %
45 %
MINOR
05 %
25 %
SEVERE
01 %
05 %
High latitudes
0-24 hr
24-48 hr
ACTIVE
15 %
05 %
MINOR
15 %
25 %
SEVERE
15 %
70 %
Space Weather Update: 08/22/2015
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