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Solar wind
speed: 438.5 km/sec
density: 4.4 protons/cm3
explanation | more data
Updated: Today at 2340 UT
X-ray Solar Flares
6-hr max: B1
1736 UT Sep12
24-hr: B2
1107 UT Sep12
explanation | more data
Updated: Today at: 2300 UT
Daily Sun: 12 Sep 13
The Earthside of the sun is very quiet. Solar activity remains low. Credit: SDO/HMI
Sunspot number: 53
What is the sunspot number?
Updated 12 Sep 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

12 Sep 2013

The Radio Sun
10.7 cm flux: 93 sfu
explanation | more data
Updated 12 Sep 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: 8.0 nT
Bz: 1.9 nT north
explanation | more data
Updated: Today at 2347 UT
Coronal Holes: 12 Sep 13
Solar wind flowing from this coronal hole could reach Earth on Sept. 14-15. Credit: SDO/AIA. is now posting daily satellite images of noctilucent clouds (NLCs), which hover over Earth's poles at the edge of space. The data come from NASA's AIM spacecraft. The north polar "daisy" pictured below is a composite of near-realtime images from AIM assembled by researchers at the University of Colorado's Laboratory for Atmospheric and Space Physics (LASP).
Noctilucent Clouds
Switch view: Europe, USA, Asia, Polar
Updated at: 09-02-2013 11:55:02
NOAA Forecasts
Updated at: 2013 Sep 12 2200 UTC
0-24 hr
24-48 hr
01 %
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: 2013 Sep 12 2200 UTC
0-24 hr
24-48 hr
30 %
10 %
15 %
05 %
01 %
01 %
High latitudes
0-24 hr
24-48 hr
15 %
15 %
30 %
25 %
45 %
20 %
Thursday, Sep. 12, 2013
What's up in space

When is the best time to see auroras? Where is the best place to go? And how do you photograph them? These questions and more are answered in a new book, Northern Lights - a Guide, by Pal Brekke & Fredrik Broms.

Northern Lights - a Guide

VOYAGER 1 ENTERS INTERSTELLAR SPACE: Researchers have long waited for one of the Voyager probes to leave the solar system. In a surprising turn of events, NASA announced today that Voyager 1 entered interstellar space a whole year ago! This event sets in motion a new era of exploration of the realm between the stars. Congratulations to the Voyager team! [full story]

In February 2012, the National Radio Astronomy Observatory's 5,000-mile-wide Very Long Baseline Array (VLBA) made a radio image of Voyager 1's signal. Little did they know, Voyager 1 was already in interstellar space:

Voyager 1's main transmitter radiates around 22 watts, which is comparable to a typical ham radio or a refrigerator light bulb. Though incredibly weak by the standards of modern wireless communications, Voyager 1's signal is bright when compared to most natural objects studied by radio telescopes.

The image is about 0.5 arcseconds on a side. An arcsecond is the apparent size of a penny as seen from 2.5 miles (4 kilometers) away. The slightly oblong shape of the image is a result of the array's configuration.

The VLBA made this image of Voyager 1's signal on Feb. 21, 2013. At the time, Voyager 1 was 11.5 billion miles (18.5 billion kilometers) away.

SOUTHEAST ERUPTION: Solar activity is low, but not zero. Yesterday, Sept. 11th, a magnetic filament snaking around the sun's southeastern limb rose up and erupted. NASA's Solar Dynamics Observatory recorded the action in a movie which spans 3.5 hours:

The filament hurled part of itself into space, and the Solar and Heliospheric Observatory recorded a bright CME billowing away from the blast site. Earth, however, was not in the line of the fire. The explosion was too far south and east to target our planet. Solar flare alerts: text, voice.

Realtime Space Weather Photo Gallery

METEOR OUTBURST? European sky watchers have witnessed an outburst of September epsilon Perseid meteors. "The outburst occurred around UT midnight on Sept. 9-10," says Bill Cooke, head of NASA's Meteoroid Environment Office. "During a two hour period, meteors appeared at a rate equivalent to ~50 per hour (ZHR). We did not see the outburst in North America because it was still daylight at the time."

NASA all-sky cameras have been recording epsilon Perseid fireballs for days, albeit at a much lower rate than what the Europeans saw. The shower has been active since early September, allowing Cooke's team to calculate orbits for more than a dozen meteoroids:

In the diagram, orbits are color-coded by velocity. Epsilon Perseid meteoroids hit Earth's atmosphere at a "blue-green" speed of about 62 km/s (139,000 mph). According to NASA data, the debris stream appears to be rich in fireball-producing meteoroids.

The epsilon Perseid shower peaks every year around this time, but the shower is not well known because it is usually weak, producing no more than 5 meteors per hour. In 2008 the shower surprised observers with an outburst five times as active, and this year the shower may have doubled even that. Clearly, the epsilon Perseid debris stream contains some dense filaments of material that Earth usually misses but sometimes hits.

No one knows the source of the September epsilon Perseid meteor shower. Whatever the parent is, probably a comet, its orbit must be similar to the green ellipses shown in the orbit-map above. As NASA cameras continue to gather data on this shower, orbital parameters will become more accurately known, possibly leading to a match.

Meanwhile, sky watchers should be alert for more epsilon Perseids in the nights ahead. The shower is waning but still active and more outbursts are possible.

Realtime Space Weather Photo Gallery

Realtime Aurora Photo Gallery

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

Realtime Comet Photo Gallery

  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 September 12, 2013 there were 1424 potentially hazardous asteroids.
Recent & Upcoming Earth-asteroid encounters:
Miss Distance
2000 DK79
Nov 10
49.1 LD
3.2 km
2011 JY1
Nov 13
8.2 LD
57 m
2001 AV43
Nov 18
3 LD
58 m
2010 CL19
Nov 25
37.6 LD
1.3 km
2013 NJ
Nov 26
2.5 LD
180 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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