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WEEKEND AURORA WATCH: NOAA forecasters estimate a 30% chance of polar geomagnetic storms this weekend as Earth approaches a high-speed stream of solar wind. Arctic sky watchers should be alert for auroras. Solar flare alerts: text, voice
COMET LOVEJOY ATTRACTS ATTENTION: Around the northern hemisphere, amateur astronomers are reporting a green fuzzball in the midnight sky. It's Comet Lovejoy (C/2014 Q2), shown here above the Dolomite mountains of northern Italy on Dec. 26th:
"I did not use a telescope to take the picture. All I needed was my Nikon digital camera," says photographer Giorgia Hofer of Misurina Lake, Italy. " The sky is a 10x30 sec exposure, and the landscape is 1x180 sec."
For weeks, this comet has been brightening in the southern sky, where it has become a favorite target for astrophotographers in Australia, New Zealand, and South America. Now it has crossed the celestial equator so that northerners can see it, too.
"I saw Comet Lovejoy last night," reports John Chumack of Yellow Springs, Ohio. "It is bright, ~ 5.5 mag, and about 13 degrees above the southern horizon at midnight. In our light polluted skies, it was barely visible to the unaided eye with averted vision but it was an easy target for binoculars." A ten minute exposure through Chumack's homemade 16-inch telescope revealed not only the comet's vivid green nucleus but also multiple delicate streamers in its sinuous tail.
Comet Lovejoy resources: photo gallery, finder charts, ephemeris, 3D orbit
Realtime Comet Photo Gallery
SUDDEN DIP IN COSMIC RAYS: Every day, Earth is bombarded by galactic cosmic rays--subatomic particles accelerated to high energies by distant supernovas, stellar flares, and other explosions. On Dec. 21st, ground-based neutron monitors detected a sudden decrease in this cosmic radiation. The following plot from the Oulu Cosmic Ray Station in Finland shows the change:
What happened? Over a 48-hour period beginning on Dec. 21st, a series of three CMEs swept past Earth, delivering glancing blows to our planet's magnetosphere. These CMEs swept aside many of the cosmic rays that would normally bombard our planet. The dip in cosmic rays is called a "Forbush Decrease," named after physicist Scott E. Forbush who first described it in the 20th century.
The ongoing Forbush Decrease is producing some of the lowest radiation levels of the current solar cycle. This is good news for airline passengers, pilots, flight attendants and astronauts, all of whom absorb cosmic rays during their travels.
To investigate how the Forbush Decrease is propagating through the atmosphere, the students of Earth to Sky Calculus gathered on Christmas Eve to launch a Space Weather Buoy:
The Buoy (inset) carried a pair of X-ray/gamma-ray sensors, a cryogenic thermometer, two GPS altimeters, a GPS tracker and three video cameras to record the trip. If everything worked as planned, the Buoy will have recorded a complete profile of ionizing radiation from ground level to 110,000 feet. The students will be able to compare the current radiation profile with dozens of previous profiles measured since 2013.
According to GPS telemetry, the payload traveled to the stratosphere and parachuted back to Earth on Dec. 24th. Update: the payload has been recovered. Stay tuned for data and footage.
Realtime Space Weather Photo Gallery
Realtime Aurora 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 Dec. 27, 2014, the network reported 18 fireballs.
(14 sporadics, 1 Quadrantid, 1 December Leonis Minorid, 1 December Hydrid, 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 December 27, 2014 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 YP9 || |
|2014 YV9 || |
|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 |