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.
CO-ROTATING INTERACTION REGION: NOAA forecasters estimate a 30% chance of polar geomagnetic storms on Sept. 23-24 when a co-rotating interaction region (CIR) is expected to hit Earth's magnetic field. CIRs are transition zones between fast- and slow-moving solar wind streams. Solar wind plasma piles up in these regions, producing density gradients and shock waves that do a good job of sparking auroras. Aurora alerts: text, voice
AURORAS LOVE EQUINOXES: The northern autumnal equinox is less than a day away. That's good news for sky watchers because, for reasons researchers do not fully understand, auroras love equinoxes. At this time of year even gentle gusts of solar wind can spark a nice display of Northern Lights:
Igor Matveev took the picture on Sept. 19th from Monchegorsk, Russia. There was no geomagnetic storm predicted that night--and no meteor shower. Yet Matveev saw both. "What luck!" he says. "I caught the entire meteor streaking beneath the auroras."
No CME was required to spark the auroras. Instead, a relatively minor fluctuation in the magnetism of the solar wind caused the display. Tomorrow's CIR (co-rotating interaction region), explained above, could be even more effective. Stay tuned to the realtime photo gallery for sightings.
Aurora Photo Gallery
ADVANCING SUNSPOTS: Over the weekend, a group of large and potentially active sunspots emerged over the sun's southeastern limb. Sergio Castillo photographed their dark cores from his backyard observatory in Corona, CA:
The largest of the new sunspots, AR2172, has a delta-class magnetic field that harbors energy for strong explosions. At the moment these sunspots are not directly facing Earth. As the week unfolds, however, they will turn toward our planet, increasing the odds of geoeffective flares. NOAA forecasters estimate a 35% chance of M-class flares and a 10% chance of X-flares during the next 24 hours. Solar flare alerts: text, voice
Aurora Photo Gallery
STUDENTS MEASURE 'FORBUSH DECREASE': On Sept. 12th, a CME hit Earth's magnetic field, igniting the most intense geomagnetic storm of the year. The students of Earth to Sky Calculus quickly launched a helium balloon to the stratosphere to see what effect the storm was having on Earth's upper atmosphere. They expected to measure more radiation than usual. Instead, they measured less. This plot shows a sharp drop in high-energy radiation on Sept. 12th compared to previous flights in May, June, and August:
What caused this counterintuitive drop? Answer: When the CME swept past Earth, it swept aside many of the cosmic rays that normally surround our planet. The effect is called a "Forbush Decrease," named after physicist Scott E. Forbush who first described it in the 20th century.
Wherever CMEs go, cosmic rays are deflected by magnetic fields inside the CME. Forbush decreases have been observed on Earth and in Earth orbit onboard Mir and the ISS. The Pioneer 10 and 11 and Voyager 1 and 2 spacecraft have experienced them, too, beyond the orbit of Neptune. Now high school students have detected a Forbush Decrease in the stratosphere using little more than an insulated lunchbox and a helium balloon.
The balloon's lunchbox-payload is shown here suspended more than 100,000 feet above the Sierras of central California:
Inside the payload, there was an ionizing radiation sensor (energy range: 10.0 KeV to 20.0 MeV), a cryogenic thermometer, multiple GPS altimeters and trackers, and three cameras. During the 2.5 hour flight, the buoy collected more than 50 gigabytes of video and science data ranging in altitude from 8500 ft to 113,700 ft above sea level. The analysis is still underway.
The students wish to thank Caisson Biotech LLC for sponsoring this flight. Note their logo on the upper right corner of the payload!
Readers, if you would like to sponsor an upcoming balloon launch and have your logo flown to the edge of space, please contact Dr. Tony Phillips to make arrangements. The cost of sponsorship is $500. Sponsors receive a complete video of the flight along with advertising exposure on spaceweather.com.
Space Weather Photo Gallery
Comet Photo Gallery
Every night, a network
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 Sep. 21, 2014, the network reported 19 fireballs.
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
all the time.
September 22, 2014 there were 1501
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.
official U.S. government space weather bureau
first place to look for information about sundogs,
pillars, rainbows and related phenomena.
call it a "Hubble for the sun." SDO
is the most advanced solar observatory ever.
views of the sun from NASA's Solar and Terrestrial
and archival images of the Sun from SOHO.
the NOAA Space Environment Center
underlying science of space weather