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Solar wind
speed: 431.0 km/sec
density: 0.6 protons/cm3
explanation | more data
Updated: Today at 2347 UT
X-ray Solar Flares
6-hr max: C4
2017 UT Apr28
24-hr: C4
2017 UT Apr28
explanation | more data
Updated: Today at: 2300 UT
Daily Sun: 28 Apr 13
Sunspot AR1731 has a beta-gamma magnetic field that habors energy for M-class solar flares. Credit: SDO/HMI
Sunspot number: 100
What is the sunspot number?
Updated 28 Apr 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

28 Apr 2013

The Radio Sun
10.7 cm flux: 127 sfu
explanation | more data
Updated 28 Apr 2013

Current Auroral Oval:
Switch to: Europe, USA, New Zealand, Antarctica
Planetary K-index
Now: Kp= 2 quiet
24-hr max: Kp= 2
explanation | more data
Interplanetary Mag. Field
Btotal: 3.3 nT
Bz: 0.2 nT south
explanation | more data
Updated: Today at 2346 UT
Coronal Holes: 28 Apr 13
Solar wind flowing from this minor coronal hole should reach Earth on ~May 2nd. Credit: SDO/AIA.
NOAA Forecasts
Updated at: 2013 Apr 28 2200 UTC
0-24 hr
24-48 hr
25 %
25 %
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: 2013 Apr 28 2200 UTC
0-24 hr
24-48 hr
10 %
10 %
01 %
01 %
01 %
01 %
High latitudes
0-24 hr
24-48 hr
15 %
15 %
15 %
20 %
10 %
20 %
Sunday, Apr. 28, 2013
What's up in space

Listen to radar echoes from satellites and meteors, live on listener-supported Space Weather Radio.

Spaceweather Radio is on the air

SATURN AT ITS BEST: Tonight, April 28th, Saturn will be at its closest to Earth for all of 2013. This is the best time to look at the ringed planet, which is glowing about twice as brightly as a 1st-magnitude star. Even small telescopes show Saturn's icy rings in crisp detail. [sky map] [NASA video]

SPACE WEATHER BALLOON POPS: Last week, we reported on a group of high school students in Bishop, CA, who are launching "space weather balloons" to the edge of space to study the effect of solar flares on Earth's ozone layer. This is what it looks like when a space weather balloon pops:

A camera atop the balloon's payload recorded the explosion at 60 frames per second, allowing the student researchers to create a slow-motion movie of the balloon tearing itself to ribbons. This was their 22nd flight to the stratosphere since 2010, so they've seen this happen many times: another movie highlights some of the best explosions so far.

The popping of the balloon is an intentional part of the mission profile. It happens at an altitude of approximately 120,000 feet above Earth's surface, well inside the ozone layer that the students wish to study. The payload then parachutes back to Earth, where students find it (often in exotic places such as Death Valley) using GPS trackers.

The name of the group is "Earth to Sky Calculus." Check their Facebook page for more information about the space weather balloon program and other activities.

EDGE-ON SUNSPOT: Big sunspot AR1726 rotated off the Earthside of the sun this weekend, surmounting the west limb of the solar disk as it headed for the sun's farside. Amateur astronomer Harald Paleske of Langendorf, Germany, took the opportunity to photograph a sunspot, edge-on:

To create this extraordinary composite image, he assembled several exposures from his 225mm Unigraph solar telescope into a single panorama spanning more than 150,000 km. It shows a maelstrom of magnetic turbulence and heaving plasma--a true solar storm.

The last time we saw it clearly, AR1726 had a delta-class magnetic field that harbored energy for powerful X-class solar flares. The flare-threat has now shifted to the farside of the sun. Earth is safe, but Mercury and Mars are in the line of fire. Solar flare alerts: text, voice.

Realtime Space Weather Photo Gallery

RESUMING COMMUNICATIONS WITH MARS: For much of April, NASA's communications with Mars have been suspended as the Red Planet passed behind the sun. Transmissions are resuming again this weekend. SOHO coronagraphs show Mars emerging from solar conjunction:

According to a NASA press release, command transmissions will resume, but with some restrictions for the next few days. By May 1st, the Mars orbiters will begin a full dump of data accumulated during the blackout period. Mars Reconnaisance Orbiter could have about 40 gigabits of data from its own science instruments and about 12 gigabits of data from Curiosity stored for sending to Earth.

Realtime Aurora Photo Gallery

Realtime Comet Photo Gallery

Realtime Noctilucent Cloud Photo Gallery
[previous years: 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2011]

  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 28, 2013 there were 1397 potentially hazardous asteroids.
Recent & Upcoming Earth-asteroid encounters:
Miss Distance
2005 NZ6
Apr 29
24.9 LD
1.3 km
2001 DQ8
Apr 30
74.3 LD
1.1 km
2004 BV102
May 25
69.9 LD
1.4 km
1998 QE2
May 31
15.2 LD
2.1 km
2000 FM10
Jun 5
50.3 LD
1.3 km
2002 KL3
Jun 6
66.4 LD
1.1 km
1999 WC2
Jun 12
39.2 LD
1.9 km
2006 RO36
Jun 18
70.9 LD
1.2 km
2001 PJ9
Jul 17
29.2 LD
1.1 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
Space Weather Alerts
  more links...
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