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GEOMAGNETIC STORM WARNING: NOAA forecasters estimate a 65% chance of geomagnetic storms on Aug. 2nd when a CME is expected to strike Earth's magnetic field. A solar wind stream following close on the heels of the CME could boost storm levels to G2 (moderately strong) by Aug.3rd. High latitude sky watchers should be alert for auroras. Aurora alerts: text or voice
NOCTILUCENT CLOUD SEASON BEGINS AND ENDS: July is a great month for noctilucent clouds (NLCs). August ... not so much. The night-shining clouds of summer almost always begin to fade as August unfolds. Around this time, sky watchers near the Arctic Circle experience a "noctilucent paradox." The season begins just as it is ending. "Last night in northern Sweden, I got to see my first noctilucent clouds of the season," reports Göran Strand, who sends this picture from Östersund at latitude 63° N:
"It was a very calm night and the NLCs were quite bright, so I went to a small lake close by," says Strand. "Sadly the NLC season here up north is really short."
It's short because the Arctic "midnight sun" wipes out the month of July, leaving only August with dark enough skies to see the electric-blue NLCs. "Last year I saw my last NLCs on August 12th during the Perseid meteor shower," Strand recalls.
On the bright side, he says, "the end of noctilucent cloud season signals the beginning of aurora season. On that very same night last year, the 12th of August, I also saw my first auroras during the Perseid meteor shower. I hope that cosmic hattrick will be visible again this year."
Realtime Noctilucent Cloud Photo Gallery
A MYSTERIOUS FORM OF AURORA: Humans have been watching the aurora borealis for thousands of years, with scientific studies of the phenomenon underway for centuries. Despite all that watching and studying, however, there are still some auroral forms that remain a mystery--namely, the "proton arc." This one appeared over the Grande Cache area of Alberta, Canada, on July 29th:
"As I was driving to the Kakwa river, I saw a purple 'proton arc' crossing the sky from east to west, pulsing and dancing with the Northern lights," says photographer Catalin Tapardel. "Quite a show...."
Aurora photographers see these structures from time to time--tight ribbons of light, sometimes red, sometimes green, writhing across the night sky. They are commonly called "proton arcs."
Yet aurora scientists say they probably have nothing to do with protons.
"My opinion, and I believe the consensus of most aurora scientists, is that these arcs are not proton related, " says Jason Ahrns, a researcher at the University of Alaska Fairbanks, "but I don't know what does cause them."
"Ordinary auroras we see from the ground and space are caused by electrons precipitating down into the atmosphere," says Dennis Gallagher of the NASA Marshall Space Flight Center. "Protons can cause auroras, too, but they are different. For one thing, proton auroras are brightest in the UV part of the spectrum, invisible to the human eye."
There is some visible light from proton auroras, but the structures they make are not tight and filamentary, but rather broad and diffuse--"in part because the gyroradius of protons is large," says Ahrns. In other words, massive protons circle around magnetic fields in broad lazy arcs unlike lightweight electrons, which can tightly circle magnetic fields to form narrow structures.
Ahrns photographed an authentic proton aurora in February 2014: photo. "It appearance matched the description of proton arcs in the scientific literature - 'a dim and diffuse glow' with 'very little structure in the observed brightness' with a total brightness of only a few kiloRayleighs, which is just on the verge of visual threshold (Lummerzheim 2001)."
So what are the "proton arcs" often photographed by amateur aurora chasers? "I don't know," says Ahrns, "but it is something many of us would like to get to the bottom of!" For more examples of this mystery in the sky, browse the Proton Arc Photo Gallery.
Realtime Proton Arc Photo Gallery
GREEN-BLOODED BOBBLEHEAD: The 50th Anniversary of Star Trek is now. To celebrate (and to support their crowdfunded research program) the students of Earth to Sky Calculus flew the pointy-eared science officer to the stratosphere on July 24, 2016. Here he is at the apex of the flight, more than 32.2 km (112,200 ft) above Earth's surface:
You can buy this collector's item for only $129.95 in the in the Earth to Sky Store.
Proceeds from the sale support space weather research. Bobblehead Spock hitchhiked on a helium balloon payload that carried an array of X-ray/gamma-ray sensors. By launching these sensors 3 or 4 times a month, the students have shown that cosmic rays are intensifying--a trend that affects mountain climbers, air travelers, high-altitude drones, and astronauts on the International Space Station.
Realtime Space Weather Photo Gallery
Realtime Aurora Photo Gallery
Realtime Sprite 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 Aug. 2, 2016, the network reported 73 fireballs.
(50 sporadics, 13 Perseids, 7 alpha Capricornids, 3 Southern delta Aquariids)
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 August 2, 2016 there were 1714 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.
| ||Cosmic Rays in the Atmosphere |
These measurements are based on regular space weather balloon flights: learn more.
|Situation Report -- Oct. 30, 2015 ||Stratospheric Radiation (+37o N) |
|Cosmic ray levels are elevated (+6.1% above the Space Age median). The trend is flat. Cosmic ray levels have increased +0% in the past month. |
|Sept. 06: 4.14 uSv/hr (414 uRad/hr) |
|Sept. 12: 4.09 uSv/hr (409 uRad/hr) |
|Sept. 23: 4.12 uSv/hr (412 uRad/hr) |
|Sept. 25: 4.16 uSv/hr (416 uRad/hr) |
|Sept. 27: 4.13 uSv/hr (413 uRad/hr) |
|Oct. 11: 4.02 uSv/hr (402 uRad/hr) |
|Oct. 22: 4.11 uSv/hr (411 uRad/hr) |
Approximately once a week, Spaceweather.com and the students of Earth to Sky Calculus fly "space weather balloons" to the stratosphere over California. These balloons are equipped with radiation sensors that detect cosmic rays, a surprisingly "down to Earth" form of space weather. Cosmic rays can seed clouds, trigger lightning, and penetrate commercial airplanes. Our measurements show that someone flying back and forth across the continental USA, just once, can absorb as much ionizing radiation as 2 to 5 dental X-rays. For example, here is the data from a flight on Oct. 22, 2015:
Radiation levels peak at the entrance to the stratosphere in a broad region called the "Pfotzer Maximum." This peak is named after physicist George Pfotzer who discovered it using balloons and Geiger tubes in the 1930s. Radiation levels there are more than 80x sea level.
Note that the bottom of the Pfotzer Maximim is near 55,000 ft. This means that some high-flying aircraft are not far from the zone of maximum radiation. Indeed, according to the Oct 22th measurements, a plane flying at 45,000 feet is exposed to 2.79 uSv/hr. At that rate, a passenger would absorb about one dental X-ray's worth of radiation in about 5 hours.
The radiation sensors onboard our helium balloons detect X-rays and gamma-rays in the energy range 10 keV to 20 MeV. These energies span the range of medical X-ray machines and airport security scanners.
| ||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 |
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