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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QUIET SUN: Despite an uptick in the sunspot number, solar activity remains low. AR2121 has a 'beta-gamma' magnetic field that harbors energy for M-class solar flares, but so far the quiet sunspot seems dis-inclined to erupt. A significant flare this weekend would be a surprise. Updates may be found on Twitter @spaceweatherman.
PERSEID METEOR SHOWER BEGINS: Earth is entering a broad stream of debris from Comet Swift-Tuttle, source of the annual Perseid meteor shower. Although the peak of the shower is not expected until August, meteors are already flitting acrosss the night sky. On July 27th, NASA cameras caught this Perseid fireball flying over New Mexico:
Over the weekend, NASA detected a total of five Perseid fireballs, a "mini-flurry" that signals the beginning of the annual display. Normally the best time to watch would be during the shower's peak: August 11th through 13th. This year, however, the supermoon will cast an interfering glare across the nights of maximum activity, reducing visibility from 120 meteors per hour (the typical Perseid peak rate) to less than 30. Instead, late July-early August might be the best time to watch as Earth plunges deeper into the debris stream before the Moon becomes full.
If you go out meteor watching in the nights ahead, you'll likely see another shower, too: the Southern Delta Aquariids. Produced by debris from Comet 96P/Machholz, this shower peaks on July 29-30 with 15 to 20 meteors per hour. This is considered to be a minor shower, but rich enough in fireballs to merit attention. NASA will stream the display from an observing site at the Marshall Space Flight Center in Alabama. Live video begins on July 29th at 9:30 pm EDT.
Got clouds? Try listening to the Perseids and the Southern Delta Aquariids on Space Weather Radio. The audio stream is playing echoes from a forward-scatter meteor radar in Roswell, New Mexico.
Realtime Space Weather Photo Gallery
AURORAS OVER CALIFORNIA ... 10 YEARS AGO: What a difference 10 years can make. The Solar Max of 2014 has been mild, producing relatively few sunspots and meagre auroras. A decade ago, however, a much more potent Solar Max was underway. A strong solar storm on July 27, 2004, sparked Northern Lights as far south as the Anza-Borrego Desert of California:
Photographer Dennis Mammana recalls the night: "It was ten years ago--during the pre-dawn hours of July 27, 2004--that the Anza-Borrego Desert of Southern California was bathed in the most unusual of light—that of the aurora borealis. On this morning it danced over so wide an area of the northern sky that it required four wide-angle images stitched carefully together to capture it all."
"As the sky darkened the night before, solar data convinced me that we in the Desert Southwest might get a rare display of Northern Lights, so I aimed a camera north and set it to take one exposure every minute. From time to time I checked the camera's LCD screen to see if it had captured anything of interest. Then, just before 4 a.m., I discovered blue streaks across the image. 'What a lousy time for the sensor to crap out on me!', I thought. But as I scrolled through the previous images to learn where it went bad, I saw the blue streaks dancing gracefully across the scene. It was the Northern Lights!"
"I hastily threw all my gear in the back of the Jeep and headed for an interesting foreground a couple of miles away. And the photo you see is the result--perhaps the only image of the northern lights with ocotillos in the foreground!"
Mammana's recollection reminds us what a "good Solar Max" is really like. There is still hope, however, that the ongoing mini-Max might produce some mid-latitude displays. Statistics of previous solar cycles show that the strongest geomagnetic storms tend to occur during the declining phase of solar cycles--in other words, just where we are now. There may yet be SoCal auroras in the offing before this Solar Max is done. Aurora alerts: text, voice
Realtime Aurora Photo Gallery
VEINS OF HEAVEN: The luminous tendrils of noctilucent clouds (NLCs) have been likened to "frozen lightning", slow-moving bolts of electric-blue that slowly zig-zag across the twilight sky during the months of Arctic summer. On July 25th photographer P-M Hedén witnessed a display over Hedesunda, Sweden, that suggested a different name. He calls them "veins of Heaven":
"I was really hoping for a good show because my children came along to watch," says Hedén. "We were not disappointed. From the beginning at 23:00 local time we saw noctilucent clouds all around the sky - amazing! Around 1 a.m. we had veins of Heaven both in the sky and reflected in the water."
Seeded by meteor smoke, are Earth's highest clouds. They glow electric-blue when sunlight strikes them more than 80 km above Earth's surface. The fine structure that resembles lightning and evokes "heavenly veins" is not fully understood. This is just one of many mysteries about NLCs that NASA has sent its AIM spacecraft to investigate.
The natural habitat of noctilucent clouds is the Arctic Circle. In recent years, however, they have spread to lower latitudes with sightings as far south as Utah and Colorado. This may yet happen in 2014. Observing tips: Look west 30 to 60 minutes after sunset when the Sun has dipped 6o to 16o below the horizon. If you see blue-white tendrils zig-zagging across the sky, you may have spotted a noctilucent cloud.
Realtime NLC Photo Gallery
Realtime Comet 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 Jul. 27, 2014, the network reported 11 fireballs.
(6 sporadics, 4 Perseids, 1 Southern delta Aquariid)
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 July 27, 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 |