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<<back forward>> -- News and information about meteor showers, solar flares, auroras, and near-Earth asteroids
Solar wind
speed: 474.2 km/sec
density: 0.9 protons/cm3
explanation | more data
Updated: Today at 2345 UT
X-ray Solar Flares
6-hr max: C1
1701 UT Apr24
24-hr: C3
0745 UT Apr24
explanation | more data
Updated: Today at: 2300 UT
Daily Sun: 24 Apr 12
Solar activity is low. None of these sunspots is actively flaring. Credit: SDO/HMI
Sunspot number: 158
What is the sunspot number?
Updated 23 Apr 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

Updated 23 Apr 2012

The Radio Sun
10.7 cm flux: 142 sfu
explanation | more data
Updated 23 Apr 2012

Current Auroral Oval:
Switch to: Europe, USA, New Zealand, Antarctica
Planetary K-index
Now: Kp= 4 unsettled
24-hr max: Kp= 6
explanation | more data
Interplanetary Mag. Field
Btotal: 11.6 nT
Bz: 4.2 nT south
explanation | more data
Updated: Today at 2346 UT
Coronal Holes: 24 Apr 12
There are no large coronal holes on the Earthside of the sun. Credit: SDO/AIA.
NOAA Forecasts
Updated at: 2012 Apr 24 2200 UTC
0-24 hr
24-48 hr
20 %
20 %
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: 2012 Apr 24 2200 UTC
0-24 hr
24-48 hr
25 %
40 %
10 %
20 %
01 %
05 %
High latitudes
0-24 hr
24-48 hr
45 %
50 %
25 %
30 %
15 %
15 %
Tuesday, Apr. 24, 2012
What's up in space

Metallic photos of the sun by renowned photographer Greg Piepol bring together the best of art and science. Buy one or a whole set. They make a stellar gift.

Metallic pictures of the Sun

SUNSET CONJUNCTION: When the sun goes down tonight, step outside and look west. Venus and the crescent Moon are shining side-by-side through the twilight. It's a beautiful way to end the day.

GEOMAGNETIC STORM: Earth is passing through the wake of a CME, and this is causing geomagnetic storms at high latitudes. Last night, auroras were spotted in more than a dozen US states including Michigan, Nebraska, Kansas, Wisconsin, North Dakota, South Dakota, Iowa, Illinois, and Colorado. Here is what the sky looked like over Grand Portage, Minnesota:

"The auroras were incredible!" says photographer Travis Novitsky.

Europeans witnessed a good show, too: "My girlfriend and I were on the Co. Antrim coast of Northern Ireland, and the auroras we saw were sublime!" reports Martin McKenna. "It's the best I've seen here since 2005, with vertical green pillars of light some 60 degrees high accompanied by amazing pulsating motions like the beating of a heart. We could even see the beams reflecting on the ocean forming their own glitter paths - what a night!"

The storm is subsiding now. Nevertheless, high-latitude sky watchers should remain alert for auroras as a fast solar wind stream continues to buffet Earth's magnetic field. Aurora alerts: text, phone.

more images: from Steve Milner of Ft St John BC Canada; from Paul Martin at the Beaghmore Stone Circles, County Tyrone, N.Ireland; from Yuichi Takasaka of Lumby, British Columbia, Canada; from Paul Kerr of Ballyliffin, Co. Donegal, Ireland; from Peter Gorman of Shroove, North Donegal, Ireland; from Jon Cooper of Hardendale, Cumbria, UK; from Douglas Kiesling of Fergus Falls, MN

SIERRA FIREBALL DECODED: On Sunday morning, April 22nd, just as the Lyrid meteor shower was dying down, a spectacular fireball exploded over California's Sierra Nevada mountain range. The loud explosion rattled homes from central California to Reno, Nevada, and beyond. According to Bill Cooke, head of NASA's Meteoroid Envronment Office, the source of the blast was a meteoroid about the size of a minivan.

"Elizabeth Silber at Western University has searched for infrasound signals from the explosion," says Cooke. "Infrasound is very low frequency sound which can travel great distances. There were strong signals at 2 stations, enabling a triangulation of the energy source at 37.6N, 120.5W. This is marked by a yellow flag in the map below."

"The energy is estimated at a whopping 3.8 kilotons of TNT, so this was a big event," he continues. "I am not saying there was a 3.8 kiloton explosion on the ground in California. I am saying that the meteor possessed this amount of energy before it broke apart in the atmosphere. [The map] shows the location of the atmospheric breakup, not impact with the ground."

"The fact that sonic booms were heard indicates that this meteor penetrated very low in atmosphere, which implies a speed less than 15 km/s (33,500 mph). Assuming this value for the speed, I get a mass for the meteor of around 70 metric tons. Hazarding a further guess at the density of 3 grams per cubic centimeter (solid rock), I calculate a size of about 3-4 meters, or about the size of a minivan."

"This meteor was probably not a Lyrid; without a trajectory, I cannot rule out a Lyrid origin, but I think it likely that it was a background or sporadic meteor."

News and eyewitness reports: #1, #2, #3, #4.

CRESCENT MOON ALERT: When the sun goes down tonight, step outside and look west into the twilight. You might see something like this:

Miguel Claro photographed the crescent moon from Almada, Portugal. "Look just below the bridge," he points out. "You can also see Jupiter."

The slender crescent will be beaming through the twilight for the next few evenings. On Tuesday, April 24th, it will glide by Venus for a spectacular sunset conjunction. Don't miss it!

more images: from Stefano De Rosa of Turin, Italy; from Robert Arn of Fort Collins, CO; from Russell Vallelunga of Phoenix, Arizona; from M. Raşid Tuğral of Ankara, Turkiye; from Zain Ahmed of Karachi, Pakistan

  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 April 24, 2012 there were 1287 potentially hazardous asteroids.
Recent & Upcoming Earth-asteroid encounters:
Miss Distance
2012 GP1
Apr 21
9 LD
26 m
2012 HN1
Apr 21
5.2 LD
18 m
2012 HE
Apr 22
6.9 LD
31 m
2012 HE2
Apr 24
8.9 LD
28 m
2012 HQ
Apr 24
9.8 LD
42 m
2012 HP13
Apr 27
2 LD
64 m
2012 HM
Apr 28
1.4 LD
67 m
2011 WV134
Apr 28
38.6 LD
1.6 km
1992 JD
May 2
9.5 LD
43 m
2010 KK37
May 19
2.3 LD
31 m
4183 Cuno
May 20
47.4 LD
5.7 km
2002 VX94
May 26
72.8 LD
1.1 km
2002 AC
Jun 16
62.2 LD
1.2 km
1999 BJ8
Jun 16
68.8 LD
1.1 km
2005 GO21
Jun 21
17.1 LD
2.2 km
2003 KU2
Jul 15
40.3 LD
1.3 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
Trade Show Displays
  more links...
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