You are viewing the page for Dec. 20, 2013
  Select another date:
<<back forward>> -- News and information about meteor showers, solar flares, auroras, and near-Earth asteroids Internet Shopping Sites high quality binoculars excellent weather stations all-metal reflector telescopes rotatable microscopes
Solar wind
speed: 359.4 km/sec
density: 3.3 protons/cm3
explanation | more data
Updated: Today at 2346 UT
X-ray Solar Flares
6-hr max: C2
1856 UT Dec20
24-hr: M3
2316 UT Dec19
explanation | more data
Updated: Today at: 2300 UT
Daily Sun: 20 Dec 13
A new sunspot (circled) emerging over the sun's southeastern limb poses a threat for M-class solar flares. Credit: SDO/HMI
Sunspot number: 138
What is the sunspot number?
Updated 20 Dec 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

20 Dec 2013

The Radio Sun
10.7 cm flux: 153 sfu
explanation | more data
Updated 20 Dec 2013

Current Auroral Oval:
Switch to: Europe, USA, New Zealand, Antarctica
Planetary K-index
Now: Kp= 2 quiet
24-hr max: Kp= 3
explanation | more data
Interplanetary Mag. Field
Btotal: 3.6 nT
Bz: 1.8 nT south
explanation | more data
Updated: Today at 2346 UT
Coronal Holes: 20 Dec 13
Solar wind flowing from the indicated coronal hole could reach Earth on or about Dec. 25th. Credit: SDO/AIA. posts 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: 12-20-2013 10:55:02
NOAA Forecasts
Updated at: 2013 Dec 20 2200 UTC
0-24 hr
24-48 hr
40 %
40 %
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: 2013 Dec 20 2200 UTC
0-24 hr
24-48 hr
05 %
05 %
01 %
01 %
01 %
01 %
High latitudes
0-24 hr
24-48 hr
15 %
15 %
15 %
15 %
05 %
05 %
Friday, Dec. 20, 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

ELECTRIC-BLUE CLOUDS OVER ANTARCTICA: A vast bank of electric-blue clouds has appeared over the south pole, signaling the start of the season for southern noctilucent clouds. According to data from NASA's AIM spacecraft, the clouds appeared earlier than usual this year. Researchers say this could be a sign of climate change: full story.

BON VOYAGE, GAIA: On Dec. 19th, the European Space Agency launched one of the most ambitious astronomy missions ever: GAIA, an observatory that will survey more than one billion stars in the Milky Way. By the time GAIA's five year mission is over, astronomers will be able to build the first accurate three-dimensional map of celestial objects in our home galaxy. GAIA will do its work from the L2 Lagrange point approximately 1.5 million km from Earth. On Dec. 20th, amateur astronomer Dave Eagle of Higham Ferrers UK observed the spacecraft hurtling toward that distant station:

"It was great to see the spacecraft in the exact position predicted, near the shield of Orion," says Eagle. "After watching the launch live on the Web in the morning, I was glad to be able to track it down and wish it well in its coming mission. It was much brighter than I expected, so its newly deployed Sun shield is doing a great job."

Once it reaches its L2 parking orbit and begins observing, GAIA will log the position, brightness and color of every star that falls within its field of view. By repeating these observations throughout its mission, astronomers will be able to calculate the distance, speed and direction of motion of each star GAIA sees, chart variations in their brightness, and determine whether they have nearby companions. This kind of detailed information about the Milky Way is unprecedented and may lead to important new discoveries about the evolution and structure of our galaxy. For updates about GAIA, stay tuned to the ESA.

Realtime Space Weather Photo Gallery

M-CLASS SOLAR FLARE: For more than two weeks, solar activity has been low. Hours ago, a new sunspot broke the quiet with an M3.5-class solar flare. NASA's Solar Dynamics Observatory recorded the extreme ultraviolet flash at 23:16 UT on Dec. 19th:

Radiation from the flare produced a brief wave of ionization in the upper atmosphere over the Pacific side of Earth. Otherwise, the blast was not particularly geoeffective. It did not produce an Earth-directed CME.

The instigating sunspot is still emerging over the sun's southeastern limb. Without a top-down view of the sunspot's magnetic field, it is difficult to assess the region's flare-producing potential. NOAA forecasters are guestimating a 30% chance of more M-class flares on Dec. 20th. Solar flare alerts: text, voice

Realtime Space Weather Photo Gallery

SOLSTICES IN A BEER CAN: The northern winter solstice is only one day away. In the Netherlands that means it's time to open up a beer can and look inside. Every six months, Jan Koeman of Zierikzee, the Netherlands, deploys a beer-can solargraph to record the progress of seasons, solstice to solstice. On Dec. 18th he cracked his open and this is what he saw:

"I made a solargraph using an empty beer tin with a pinhole and photographic paper inside," explains Koeman. "The exposure time is 6 months!"

The highest arcs were traced by the summer sun ofJune 2013. The lowest arc was made by the sun on Dec. 18th, just three days before the 2013 winter solstice. Occasional gaps are caused by clouds.

"This year I placed my solargraph high and safe on an old Dutch windmill," continues Koeman. "The miller is always busy and we have a lot of wind here, so the spinning wings of the mill are barely visible in the photo."

Readers: Northern winter begins on Dec. 21st at 17:11 UT. Now is the perfect time to deploy your own beer-can solargraph for the next six months. Too young to drink? Soda cans work, too. 6-month Solargraph How-to Guides: #1, #2, #3

Realtime Space Weather Photo Gallery

Realtime Aurora 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 Dec. 19, 2013, the network reported 29 fireballs.
(24 sporadics, 2 Comae Berenicids, 2 December Leonis Minorids, 1 sigma Hydrid)

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]

On Dec. 18, 2013, the network reported 12 fireballs.
(10 sporadics, 1 sigma Hydrid, 1 December Leonis Minorid)

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 December 20, 2013 there were potentially hazardous asteroids.
Recent & Upcoming Earth-asteroid encounters:
Miss Distance
2013 XH22
Dec 18
1.9 LD
27 m
2011 YD29
Dec 28
6.1 LD
24 m
2007 SJ
Jan 21
18.9 LD
1.9 km
2012 BX34
Jan 28
9.6 LD
13 m
2006 DP14
Feb 10
6.2 LD
730 m
2000 EM26
Feb 18
8.8 LD
195 m
2000 EE14
Mar 6
64.6 LD
1.8 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...
©2010 All rights reserved. This site is penned daily by Dr. Tony Phillips.
©2019 All rights reserved.