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Solar wind
speed: 328.3 km/sec
density: 5.0 protons/cm3
explanation | more data
Updated: Today at 2349 UT
X-ray Solar Flares
6-hr max: B4
2201 UT Apr28
24-hr: C1
0519 UT Apr28
explanation | more data
Updated: Today at: 2300 UT
Daily Sun: 28 Apr 15
None of these sunspots poses a threat for strong flares. Solar activity is low. Credit: SDO/HMI

Sunspot number: 42
What is the sunspot number?
Updated 28 Apr 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 28 Apr 2015

The Radio Sun
10.7 cm flux: 108 sfu
explanation | more data
Updated 28 Apr 2015

Current Auroral Oval:
Switch to: Europe, USA, New Zealand, Antarctica
Credit: NOAA/Ovation
Planetary K-index
Now: Kp= 1 quiet
24-hr max: Kp= 2
explanation | more data
Interplanetary Mag. Field
Btotal: 4.3 nT
Bz: 2.4 nT south
explanation | more data
Updated: Today at 2349 UT
Coronal Holes: 28 Apr 15

Solar wind flowing from this coronal hole should reach Earth on ~May 3-4. Credit: SDO/AIA.
Noctilucent Clouds The southern season for NLCs has come to an end. The last clouds were observed by NASA's AIM spacecraft on Feb. 20, 2015. Now attention shifts to the northern hemisphere, where the first clouds of 2015 should appear in mid-May.
Switch view: Ross Ice Shelf, Antarctic Penninsula, East Antarctica, Polar
Updated at:
NOAA Forecasts
Updated at: 2015 Apr 28 2200 UTC
0-24 hr
24-48 hr
05 %
01 %
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: 2015 Apr 28 2200 UTC
0-24 hr
24-48 hr
15 %
20 %
05 %
05 %
01 %
01 %
High latitudes
0-24 hr
24-48 hr
15 %
15 %
25 %
30 %
20 %
25 %
Tuesday, Apr. 28, 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.

Lapland tours

MICROBES IN THE STRATOSPHERE: In just a few hours, and the students of Earth to Sky Calculus are going to launch a colony of halobacteria to the stratosphere. The purpose of this ongoing experiment is to find out if the terretrial extremophile can survive Mars-like conditions high above Earth's surface. If the answer is "yes," cousins of halobacteria might one day be found on the Red Planet. Stay tuned for updates.

EXPLOSION ON THE SUN: For days, astronomers have been monitoring a magnificent filament of magnetism stretching across the face of the sun. This morning, April 28th, it erupted. NASA's Solar Dynamics Observatory recorded the blast:

Hurled upward by magnetic instabilities, the erupting filament split the sun's atmosphere, creating a "canyon of fire." The glowing walls of the canyon trace the original channel where the filament was suspended by magnetic forces above the sun's surface. From end to end, the structure stretches more than 350,000 km--a real Grand Canyon:

A coronal mass ejection (CME) is also emerging from the blast site: SOHO image. At first glance, the CME appears to be moving well away from the sun-Earth line. However, coronagraph data are too preliminary to rule out a glancing blow to our planet in the days ahead. Stay tuned for updates. Solar flare alerts: text, voice.

Realtime Space Weather Photo Gallery

STUBBORN AURORAS: On April 27th, Earth passed through a fold in the heliospheric current sheet. This sparked a display of "stubborn auroras" around the Arctic Circle. Thomas Kast sends this picture from Vihiluoto, Finland:

"Bright summer nights are taking over," says Kast. "When I took this photo at 1:28 am, the sun was only 11o below the horizon. As you see in the photo, the aurora not only had to fight against the twilight but also the city lights of Oulu on the right and the bright Moon to its left. "

"For two more days auroras can theoretically be seen here [at latitude +65 N]," he adds.

That might not be enough time. The next display of Arctic auroras is expected three days from now when a minor CME might sideswipe Earth's magnetic field. Just how stubborn can Northern Lights be? Stay tuned. Aurora alerts: text, voice.

Realtime Aurora Photo Gallery

VOLCANIC PLUME = COLORFUL SUNSETS: European MetOp satellites have been monitoring aerosols blasted into the atmosphere by Chile's Calbuco volcano on April 22nd. This 5-day movie shows a plume of sulfur dioxide spreading east from Chile to Brazil:

Credit: The Global Ozone Monitoring Experiment-2 (GOME-2) onboard MetOp-A and MetOp-B

The effect of this plume on Brazilian sunsets has been dramatic. Helio C. Vital of Rio de Janeiro reports: "Pushed by strong winds, aerosols from Calbuco reached Rio on April 26th and produced an spectacular display of bright unusual colors across most of the western sky during evening twilight. The red-magenta glow lasted until an hour after local sunset."

This is what he saw:

As the sun set and the twilight faded, Jupiter and the Moon over Rio were surrounded by a distinctly purple hue.

Purple is one of the telltale signs of a volcanic sunset. Fine volcanic aerosols in the stratosphere scatter blue light which, when mixed with ordinary sunset red, produces a violet hue. But purple isn't the only thing to look for, says atmospheric optics expert Les Cowley. In addition, he advises, sky watchers in Chile and Brazil should "be alert for a very bright yellow twilight arch, fine cloud structure in the arch seen through binoculars, and long diffuse rays and shadows."

Stay tuned for updates from beneath the volcanic plume.

Realtime Space Weather Photo Gallery

Realtime Comet 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 Apr. 28, 2015, the network reported 10 fireballs.
(10 sporadics)

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 April 28, 2015 there were 1575 potentially hazardous asteroids.
Recent & Upcoming Earth-asteroid encounters:
Miss Distance
2015 HO116
Apr 27
1.7 LD
31 m
2015 HA117
Apr 27
7.2 LD
15 m
2015 GB14
Apr 28
9 LD
37 m
2015 HD10
Apr 29
1.6 LD
20 m
2015 HS11
May 1
7.1 LD
15 m
5381 Sekhmet
May 17
62.8 LD
2.1 km
2015 HT9
May 25
12.2 LD
24 m
2005 XL80
Jun 4
38.1 LD
1.0 km
2012 XB112
Jun 11
10.1 LD
2 m
2015 HM10
Jul 7
1.4 LD
65 m
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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