Would you like a call when things are happening in the night sky? Sign up for backyard astronomy alerts from spaceweather.com: voice or text.
QUIET WITH A CHANCE OF FLARES: Solar activity has been low for almost a week. Two sunspots, one old and one new, could break the quiet. AR2192 and AR2216 have tangled magnetic fields poised to criss, cross, and explode. NOAA forecasters estimate a 25% chance of an X-flare on Nov. 24rd. Solar flare alerts: text, voice
AURORA OUTBURST: On Sunday night, a bright display of auroras erupted around the Arctic Circle. Ole Salomonsen photographed the outburst behind EISCAT's ionospheric radar in Tromsø, Norway:
"After a long day of photographing whales at sea, I was looking forward to relaxing in the evening, but Lady aurora invited me out, and I could not resist," says Salomonsen. "After quickly getting new batteries and memory cards for my camera, I went out hunting, this time for the magic emerald light. The entire sky was filled with majestic moving green auroras. At times there were 4 to 5 arcs stretching from east to west next to each other in the sky. This was really amazing to watch!"
Bright auroras arre often caused by CME impacts, but there was no CME on Sunday. Instead, the interplanetary magnetic field (IMF) near Earth tilted south. This opened a crack in Earth's magnetosphere. Solar wind poured in to fuel the display. Aurora alerts: text, voice
Aurora Photo Gallery
LUNAR TRANSIT OF THE SUN: On Saturday, Nov. 22nd, the Moon passed in front of the sun, producing a partial solar eclipse. No one on Earth saw it; the lunar transit was visible only from Earth orbit. More than 22,000 miles above our planet's surface, NASA's Solar Dynamics Observatory (SDO) snapped this picture:
Using a bank of 16-megapixel cameras, SDO observed the event at multiple extreme ultraviolet wavelengths. Scan the edge of the Moon in the 171 Å high-resolution image, shown below. The little bumps and irregularities you see are lunar mountains backlit by solar plasma:
Beyond the novelty of observing an eclipse from space, these images have practical value to the SDO science team. The sharp edge of the lunar limb helps researchers measure the in-orbit characteristics of the telescope--e.g., how light diffracts around the telescope's optics and filter support grids. Once these are calibrated, it is possible to correct SDO data for instrumental effects and sharpen the images even more than before.
Space Weather Photo Gallery
SUB-SUNDOG: Next week's Thanksgiving is the biggest travel holiday of the year in the United States. Millions of people board airplanes and fly long hours to visit friends and family. Dreading the trip? Think of it as a sky watching opportunity. There are some things you can see only through the window of an airplane--like this:
"In the tops of the clouds, I saw a bright reflection of the sun flanked by rainbow-colored sundogs," says Alex Ruege, who snapped the picture on November 14th while he was flying over Phoenix, Arizona.
Atmospheric optics expert Les Cowley explains the apparition: "Look down from the sunny side of an aircraft and you will often see a dazzling reflection of the sun in the clouds. This is a subsun, formed by millions of plate shaped ice crystals acting as mirrors. Sometimes the subsun is flanked by two colorful sub-sundogs. How do they form? Sunlight nearly always bounces up and down inside the thin ice plates before it can emerge. An even number of bounces make a sundog. An odd number makes the sub-sundog. When you see halos always check out the opposite direction – you might see even rarer sights!"
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 Nov. 23, 2014, the network reported 11 fireballs.
(9 sporadics, 1 Quadrantid, 1 alpha Monocerotid)
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.
November 24, 2014 there were 1514
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