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CHANCE OF FLARES: NOAA forecasters estimate a 50% chance of M-class solar flares on Jan. 6th. The likely source would be Earth-facing sunspot AR2253, a large active region with an unstable 'beta-gamma-delta' magnetic field. Solar flare alerts: text, voice
RADS ON A PLANE, CONTINUED: Many people think you have to go all the way to the Arctic Circle to experience space weather. Not so. All you have to do is board an airplane. Every day more than 8 million people fly somewhere on Earth. All of them are exposed to cosmic rays, a form of high-energy space radiation. To illustrate the point, yesterday Dr. Tony Phillips of spaceweather.com carried a pair of ionizing radiation detectors onboard a US Airways flight from Reno to Phoenix. At cruising altitude (38,700 ft) he measured dose rates 42 times higher than at ground level:
At this rate, a passenger flying for 5 hours could be exposed to about as much radiation as a dental X-ray--not dangerous, but not negligible either.
The radiation comes from space. Cosmic rays are subatomic particles accelerated to nearly light speed by supernovas, active galactic nuclei, and solar flares. Earth is peppered with this kind of radiation, every day, from all directions. Cosmic rays penetrate our planet's atmosphere, producing a spray of secondary particles that air travelers routinely (and mostly unknowingly) absorb as they fly.
Cosmic rays are a genuine form of space weather. They fluctuate in response to solar storms--both up and down. For example, solar flares can accelerate energetic particles toward Earth, adding to the flux of cosmic rays. CMEs, on the other hand, sweep aside cosmic rays, causing radiation counts to dip. When you step on a plane, you're never quite sure what you're going to get.
Case in point: Phillips took the same flight from Reno to Phoenix on Nov. 11, 2014. He measured 40% more radiation then vs. now. The difference is not fully understood.
Here are the data from yesterday's flight:
The two curves, orange and blue, trace data from two identical yet independent radiation detectors. Differences between the two curves are an indication of the measurement uncertainty. Using helium balloons, spaceweather.com and the students of Earth to Sky Calculus have flown these detectors to the stratosphere dozens of times to monitor the response of Earth's upper atmosphere to solar storms. They are sensitive to ionizing radiation such as X-rays and gamma-rays in the energy range 10 keV to 20 MeV.
It is important to note that these sensors sample only a fraction of the total radiation. In particular, they are not sensitive to neutrons, a key form of biologically effective radiation at aviation altitudes. Adding neutrons to the count could more than double the measured dose.
Later today, Phillips will fly back from Phoenix to Reno. What will he measure then? Stay tuned!
Realtime Aurora Photo Gallery
VENUS AND MERCURY: Tonight, when the sun goes down, step outside and face west. Mercury and Venus are converging in the sunset sky. Venus is on top in this picture taken by Giorgia Hofer on Jan. 3rd:
"I was standing on top of Monte Rite (2,300 m) in the Italian Dolomites," says Hofer. "The two planets were an easy target for my Nikon digital camera with a 3 second exposure."
As the week unfolds, the two planets will draw closer and closer together. On the date of closest approach, Jan. 10th, they will be a scant 0.7 degrees apart--a conjunction so tight you can block it out with the tip of your pinky finger held at arm's length.
Venus is the brighter of the two, by a factor of approximately 16. If you can't see Mercury with the naked eye, you might be looking too soon after sunset. Wait a while for the twilight to deepen. Or if you have binoculars, aim them at Venus to reel in Mercury.
Monitor Spaceweather.com's photo gallery for Venus-Mercury snapshots from around the world. Better yet, go outside and see for yourself.
Realtime Space Weather Photo Gallery
Realtime Comet Photo Gallery
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 Spaceweather.com.
On Jan. 6, 2015, the network reported 34 fireballs.
(28 sporadics, 2 Quadrantids, 2 December Leonis Minorids, 1 lambda Bootid, 1 alpha 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]
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 January 6, 2015 there were potentially hazardous asteroids.
Recent & Upcoming Earth-asteroid encounters: 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.
|Asteroid || |
|2014 YE42 || |
|2014 YP34 || |
|2007 EJ || |
|1991 VE || |
|2004 BL86 || |
|2008 CQ || |
|2000 EE14 || |
| ||The official U.S. government space weather bureau |
| ||The first place to look for information about sundogs, pillars, rainbows and related phenomena. |
| ||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 |
| ||Realtime and archival images of the Sun from SOHO. |
| ||from the NOAA Space Environment Center |
| ||the underlying science of space weather |