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.
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CHANCE OF STORMS: NOAA forecasters estimate a 35% to 60% chance of polar geomagnetic storms on April 1-2 when at least three CMEs are expected to deliver glancing blows to Earth's magnetic field. The best-guess forecast calls for minor G1-class storms. High-latitude sky watchers should be alert for auroras. Aurora alerts: text, voice
IMPULSIVE SOLAR FLARE SCRAMBLES RADIO SIGNALS: On Saturday, March 29th, the magnetic canopy of sunspot AR2017 erupted, producing a brief but intense X1-class solar flare. A flash of extreme UV radiation sent waves of ionization rippling through Earth's upper atmosphere and disturbed the normal propagation of terrestrial radio transmissions. Radio engineer Stan Nelson of Roswell, NM, was monitoring WWV at 20 MHz when the signal wobbled then disappeared entirely for several minutes:
"The Doppler shift of the WWV signal (the 'wobble' just before the blackout) was nearly 12 Hz, the most I have ever seen," says Nelson.
The flare not only blacked out radio signals, but also produced some radio signals of its own. The explosion above sunspot AR2017 sent shock waves racing through the sun's atmosphere at speeds as high as 4800 km/s (11 million mph). Radio emissions stimulated by those shocks crossed the 93 million mile divide to Earth, causing shortwave radio receivers to roar with static. Here is a plot of the outburst detected by Nelson using a 20.1 MHz RadioJove receiver. Elsewhere, strong bursts were recorded at frequencies as high as 2800 MHz. It was a very broad band event.
NASA's Solar Dynamics Observatory recorded a beautiful movie of the flare:
The flash you just saw was extreme UV radiation, the type of radiation that ionizes the upper layers of our atmosphere. In this case, the ionizing action of the flare led to a rare magnetic crochet, measuring 17 nT at the magnetometer in Boulder, Colorado.
A magnetic crochet is a ripple in Earth's magnetic field caused by electrical currents flowing in air 60 km to 100 km above our heads. Unlike geomagnetic disturbances that arrive with CMEs days after a flare, a magnetic crochet occurs while the flare is in progress. They tend to occur during fast impulsive flares like this one.
The magnetic field of sunspot AR2017 is decaying now, but it still poses a threat for eruptions. NOAA forecasters estimate a 55% chance of M-class flares and a 20% chance of X-class flares on March 31st. Solar flare alerts: text, voice
Realtime Space Weather Photo Gallery
OPPOSITION OF MARS: Earth and Mars are converging for a close encounter in April. It's only March, but the view through backyard telescopes is already superb. Michael A. Phillips of Swift Creek, NC, took this picture using a 14-inch telescope on March 27:
In Phillips's picture, south is up. It shows the rapidly evaporating North Polar Cap (summer arrived in February), orographic clouds over martian volcanoes near the equator, and a bright blue cloud filling Hellas Basin in the south. Only an experienced astrophotographer can produce this kind of Hubblesque detail using backyard optics. Novice observers looking through the eyepiece of a small telescope can still see a lot, however, including the rusty-red disk of Mars and bright smudges corresponding to the polar cap and Hellas Basin.
The view will improve in April. Get ready to see the Red Planet at its best as explained in "The Opposition of Mars" from Science@NASA.
Realtime Mars Photo Gallery
Realtime Comet 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 Mar. 30, 2014, the network reported 3 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 ones
all the time.
On March 31, 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.
| ||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 |