You are viewing the page for Dec. 4, 2015
  Select another date:
<<back forward>> -- News and information about meteor showers, solar flares, auroras, and near-Earth asteroids
Solar wind
speed: 367.3 km/sec
density: 6.1 protons/cm3
explanation | more data
Updated: Today at 2349 UT
X-ray Solar Flares
6-hr max: C1
1738 UT Dec04
24-hr: C1
1738 UT Dec04
explanation | more data
Updated: Today at: 2300 UT
Daily Sun: 04 Dec 15
None of these sunspots has the type of unstable magnetic field that poses a threat for strong flares. Solar activity remains low. Credit: SDO/HMI

Sunspot number: 47
What is the sunspot number?
Updated 04 Dec 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 04 Dec 2015

The Radio Sun
10.7 cm flux: 95 sfu
explanation | more data
Updated 04 Dec 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= 3
explanation | more data
Interplanetary Mag. Field
Btotal: 7.9 nT
Bz: 0.2 nT north
explanation | more data
Updated: Today at 2349 UT
Coronal Holes: 04 Dec 15

Solar wind flowing from this broad coronal hole could reach Earth as early as Dec. 7th. Credit: SDO/AIA.
Noctilucent Clouds The southern season for noctilucent clouds is about to begin. Monitor the daily daisies, below, from NASA's AIM spacecraft for the first wisps of electric blue above Antarctica.
Switch view: Ross Ice Shelf, Antarctic Peninsula, East Antarctica, Polar
Updated at: 12-03-2015 17:55:03
NOAA Forecasts
Updated at: 2015 Dec 04 2200 UTC
0-24 hr
24-48 hr
05 %
05 %
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 Dec 04 2200 UTC
0-24 hr
24-48 hr
15 %
35 %
05 %
20 %
01 %
05 %
High latitudes
0-24 hr
24-48 hr
20 %
10 %
25 %
30 %
20 %
55 %
Friday, Dec. 4, 2015
What's up in space

Marianne's Heaven On Earth Aurora Chaser Tours invites you to join them in their quest to find and photograph the Aurora Borealis. Experience the winter wonderland in the Tromsø Area.

Chase the Light Tours

SIGMA HYDRID METEORS: Last night, Dec. 3-4, NASA's network of all-sky meteor cameras recorded 8 fireballs from the sigma Hydrid meteoroid stream. These meteoroids come from an unknown comet or asteroid. Earth passes through the sigma Hydrid stream every year in early- to mid- December. Typically, the shower produces no more than 1 or 2 faint meteors per hour. The detection of 8 bright fireballs in a single night suggests that sigma Hydrid activity could be higher than usual. Listen for sigma Hydrid echoes in the audio feed from our live meteor radar.

SPACECRAFT BUZZES EARTH, PROCEEDS TO ASTEROID: Japan's Hayabusa 2 spacecraft swung past Earth on Dec 3rd at 7:08 p.m. JST, passing over the Pacific Ocean around the Hawaiian islands at an altitude of about 3,090 km. JAXA (the Japanese space agency) has just released these images of our planet taken by the speeding probe:

More images are available here with captions in Japanese.

The flyby was a slingshot maneuver designed to propel Hayabusa 2 toward asteroid Ryugu, the target of an ambitious sample return mission in 2018-2020. JAXA says the spacecraft is in good health following its close encounter with Earth. [press release]

DAWN COMET HAS TWO TAILS: Now that the morning Moon is waning in brightness, amateur astronomers are once again getting a good view of Comet Catalina. Images reveal not one, but two tails. Randy Carter sends this picture from Elkin, North Carolina, taken Dec. 4th:

"This is a 420 second exposure through my 6-inch Celestron telescope," says Carter. "I estimate the magnitude of the comet to be approximately +7."

That means Comet Catalina is too dim to see with the unaided eye, but an easy target for backyard telescopes as it glides through the constellation Virgo in the predawn sky not far from the planet Venus. Sky maps and observing tips may be found in this article from Sky and Telescope.

Why does Comet Catalina have two tails? Almost all comets do. The sun-warmed nucleus of a comet spews a mixture of dust and gas into space. Quickly, the mixture separates into two distinct tails: The gaseous "ion tail" is pushed straight away from the sun by solar wind. The weightier dust tail resists solar wind pressure and aligns itself more or less with the comet's orbit. In Carter's picture of Comet Catalina, the ion tail points up; the dust tail points down.

This is Comet Catalina's first visit to the inner solar system--and its last. The comet's close encounter with the sun in mid-November has placed it on a slingshot trajectory toward interstellar space. It will become easier to see in the weeks ahead as it recedes from the sun, possibly brightening to 5th or 6th magnitude. A date of special interest is Dec. 7th when the comet pairs up with the planet Venus and the waning crescent Moon in the early morning sky. Catalina will be about 4o degrees away from the Venus-Moon combo. Stay tuned for more information about that, and meanwhile browse the realtime comet gallery for more sightings.

Realtime Comet Photo Gallery

VAST HOLE OPENS IN SUN'S ATMOSPHERE: A vast hole in the sun's atmosphere--a "coronal hole"--has opened up in the sun's northern hemisphere, and it is spewing a broad stream of solar wind into space. NASA's Solar Dynamics Observatory photographed the coronal hole during the early hours of Dec. 3rd:

Coronal holes are places where the sun's magnetic field opens up and allows solar wind to escape. Hot plasma flows outward at speeds exceeding a million mph. In the extreme-ultraviolet image, above, the boundaries of the coronal hole are traced by dashed lines; arrows indicate the escape of hot plasma.

Solar wind flowing from this coronal hole will reach Earth beginning ~Dec. 6th, and our solar wind environment will be dominated the stream for days after first contact. High-latitude sky watchers should be alert for auroras. Aurora alerts: text or voice

Realtime Aurora Photo Gallery

GEMINID METEOR SHOWER: Earth is entering a stream of gravelly debris from "rock comet" 3200 Phaethon, source of the annual Geminid meteor shower. On the night of Dec. 2-3, NASA's network of all-sky cameras detected three Geminid fireballs over the USA. This specimen from the desert southwest was even brighter than a passing airplane:

The Geminid hit Earth's atmosphere traveling 36 km/s (81 thousand mph) and disintegrated completely 47 km (29 miles) above Earth's surface. These values are typical of Geminids.

Meteor sightings will increase in the nights ahead as Earth plunges deeper into the debris stream. Forecasters expect peak rates to occur on Dec. 13-14, when dark-sky observers in both hemispheres could see as many as 120 meteors per hour. Observing conditions will be nearly ideal because the shower peaks just a few days after the New Moon. Stay tuned for updates and, meanwhile, listen for Geminid echoes in the audio feed from our live meteor radar.

Realtime Space Weather Photo Gallery

Realtime Noctilucent Cloud Photo Gallery

Realtime Meteor 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. 4, 2015, the network reported 32 fireballs.
(22 sporadics, 8 sigma Hydrids, 1 Geminid, 1 Puppids-Velid)

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 4, 2015 there were 1638 potentially hazardous asteroids.
Recent & Upcoming Earth-asteroid encounters:
Miss Distance
2007 BG29
Dec 1
54.1 LD
1.1 km
2015 WZ12
Dec 1
8.8 LD
23 m
2015 XP
Dec 5
1.4 LD
33 m
2015 WA13
Dec 6
7.5 LD
25 m
2015 WF13
Dec 7
10.8 LD
80 m
2015 VZ145
Dec 8
9.2 LD
80 m
2015 XC
Dec 8
3.3 LD
42 m
1998 WT24
Dec 11
10.9 LD
1.1 km
2011 YD29
Dec 24
9.7 LD
24 m
2003 SD220
Dec 24
28.4 LD
1.8 km
2008 CM
Dec 29
22.8 LD
1.5 km
2004 MQ1
Jan 2
55.4 LD
1.1 km
1999 JV6
Jan 6
12.6 LD
410 m
1685 Toro
Jan 22
60.9 LD
1.7 km
2001 XR1
Jan 23
74.4 LD
1.5 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.
  Cosmic Rays in the Atmosphere
Situation Report -- Oct. 30, 2015 Stratospheric Radiation (+37o N)
Cosmic ray levels are elevated (+6.1% above the Space Age median). The trend is flat. Cosmic ray levels have increased +0% in the past month.
Sept. 06: 4.14 uSv/hr (414 uRad/hr)
Sept. 12: 4.09 uSv/hr (409 uRad/hr)
Sept. 23: 4.12 uSv/hr (412 uRad/hr)
Sept. 25: 4.16 uSv/hr (416 uRad/hr)
Sept. 27: 4.13 uSv/hr (413 uRad/hr)
Oct. 11: 4.02 uSv/hr (402 uRad/hr)
Oct. 22: 4.11 uSv/hr (411 uRad/hr)
These measurements are based on regular space weather balloon flights: learn more.

Approximately once a week, and the students of Earth to Sky Calculus fly "space weather balloons" to the stratosphere over California. These balloons are equipped with radiation sensors that detect cosmic rays, a surprisingly "down to Earth" form of space weather. Cosmic rays can seed clouds, trigger lightning, and penetrate commercial airplanes. Our measurements show that someone flying back and forth across the continental USA, just once, can absorb as much ionizing radiation as 2 to 5 dental X-rays. Here is the data from our latest flight, Oct. 22nd:

Radiation levels peak at the entrance to the stratosphere in a broad region called the "Pfotzer Maximum." This peak is named after physicist George Pfotzer who discovered it using balloons and Geiger tubes in the 1930s. Radiation levels there are more than 80x sea level.

Note that the bottom of the Pfotzer Maximim is near 55,000 ft. This means that some high-flying aircraft are not far from the zone of maximum radiation. Indeed, according to the Oct 22th measurements, a plane flying at 45,000 feet is exposed to 2.79 uSv/hr. At that rate, a passenger would absorb about one dental X-ray's worth of radiation in about 5 hours.

The radiation sensors onboard our helium balloons detect X-rays and gamma-rays in the energy range 10 keV to 20 MeV. These energies span the range of medical X-ray machines and airport security scanners.

  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
Synergy Spray Foam Insulation of Houston TX
  Protection from the Sun!
Kotton Grammer, Search Engine Marketing
  a sponsor of
Columbia Northern High School
  Web-based high school science course with free enrollment
  the underlying science of space weather
  more links...
©2015 All rights reserved. This site is penned daily by Dr. Tony Phillips.
©2019 All rights reserved.