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CHANCE OF FLARES: Today, Nov. 18th, NOAA forecasters estimate a 25% chance of X-class solar flares. The likely source would be old sunspot AR2192, now making its second trip across the face of the sun. AR2192 has an unstable 'beta-gamma-delta' magnetic field that harbors energy for strong explosions. Solar flare alerts: text, voice
GEOMAGNETIC UNREST: Around the Arctic Circle this week, solar wind buffeting Earth's magnetic field has sparked bright Northern Lights. On Sunday morning in Iceland, Vincent Brady took a panoramic photo of the display and wrapped it around his observing site to create a "planet aurora":
"This was the best display I've seen over the past month!" he says. "It was a magical spectacle early in the morning Sunday at Kirkjufell." The peak at the "top of the world" is Church Mountain.
More auroras are in the offing, especially on Nov. 20th when a minor CME might sideswipe Earth's magnetic field. The storm cloud was propelled away from the sun on Nov. 15th by an M3-class explosion from old sunspot AR2192. A glancing blow combined with already-elevated solar wind speeds could ignite a polar geomagnetic storm when the CME arrives. Solar flare alerts: text, voice
Realtime Aurora Photo Gallery
RADS ON A PLANE--THE RETURN FLIGHT: Regular readers of Spaceweather.com have been following the travels of Tony Phillips, who spent the past week flying commercial jets back and forth across the USA for meetings in Washington DC. In addition to his usual baggage, he carried a pair of radiation sensors onboard. Sitting in the economy section of a US Airways flight from Reno to Phoenix on Nov. 11th, Phillips recorded dose rates which were almost 30 times higher than background dose rates at ground level. On Nov. 15th, he gathered data from a return leg, American Airlines flight 2407 from Washington DC to Chicago. It was only half as bad:
The radiation inside these planes comes from space--that is, cosmic rays that penetrate Earth's atmosphere and reach down to aviation altitudes. In the plot we can see what a difference altitude makes: Cruising at 39,000 feet, the Reno to Phoenix flight was closer to space and thus experienced double the radiation of the DC to Chicago flight cruising at 28,000 feet.
The radiation sensor Phillips used to make these measurements is the same one that Earth to Sky Calculus routinely flies onboard helium balloons to measure cosmic rays in the stratosphere. It detects X-rays and gamma-rays in the energy range 10 keV to 20 MeV, similar to energies used by medical X-ray machines and airport security scanners.
We can put these doses into context by comparing them to medical X-rays. In a single hour flying between Reno and Phoenix on Nov. 11th, the passengers were exposed to about the same amount of radiation as an X-ray at the dentist's office. Such a dose is not a big deal for an occasional flier, but as NASA points out, frequent fliers of 100,000 miles or more can accumulate doses equal to 20 chest X-rays or about 100 dental X-rays. Lead aprons, anyone?
Some experts reading these reports on Spaceweather.com have pointed out that X-rays and gamma-rays represent only a fraction of the radiation present at aviation altitudes. The true dose could be doubled or tripled by neutrons, a component of cosmic rays known to be especially good at delivering energy to human tissue.
Realtime Space Weather Photo Gallery
Realtime Comet Photo Gallery
Realtime Eclipse 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 Nov. 18, 2014, the network reported 62 fireballs.
(35 sporadics, 19 Leonids, 6 Northern Taurids, 1 omicron Eridanid, 1 November omega Orionid)
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 November 18, 2014 there were potentially hazardous asteroids. 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.
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| ||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 |
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