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QUIET SUN: With no sunspots actively flaring, solar activity is low. According to NOAA, the odds of a significant solar flare (M- or X-class) today are no more than 1%. Solar flare alerts: text, voice
SATURN'S RINGS TO SURGE IN BRIGHTNESS: This Friday night, May 22nd, Saturn will be "at opposition"--that is, opposite the sun in the skies of Earth. The ringed planet rises in the east at sunset and soars through the southern sky at midnight, a golden "star" in the constellation Scorpius. [sky map]
Whenever Saturn is at opposition, its rings surge in brightness. Why? Scroll down for the explanation. On the way, check out these photos taken by amateur astronomer Anthony Wesley on May 19th:
"This is an animation of two Saturn images about 10 minutes apart," says Wesley, who used a 16-inch telescope in Australia. It shows gaps in Saturn's rings, clouds in the planet's atmosphere, and a famous hex-shaped storm around Saturn's north pole.
Getting such Hubblesque results from a backyard telescope requires a combination of good seeing and long years of experience. Wesley is one of the world's top amateur astrophotographers and he routinely produces images like this. Observers with less experience can take good photos, too, especially in the nights ahead as Saturn's rings brighten.
The brightening of Saturn's rings is called the "opposition effect." Saturn's rings are made of frozen chunks ranging in size from dust to houses. Sunlight directly backscattered from those ice particles causes the ring system to shine even more than usual for a few days around opposition. The exact mechanism involves shadow-hiding and possibly coherent backscattering.
If you have a telescope, take a look! Or sign up for a live view of Saturn from Slooh--no telescope required.
Realtime Space Weather Photo Gallery
SPRITE SEASON BEGINS: High above Earth in the realm of meteors and noctilucent clouds, a strange and beautiful form of lightning dances at the edge of space. Researchers call the bolts "sprites"; they are red, fleeting, and tend to come in bunches. Note to sky watchers: Sprite season is underway. Martin Popek photographed these specimens over Nydek, Czech republic, on May 13th:
One night later, May 14th, near Santa Fe, New Mexico, "I captured my first sprites of the season," reports photographer Jan Curtis. "The thunderstorm that produced them was about 200 miles to my south-southwest."
Because sprites are associated with thunderstorms, they tend to occur in late spring and summer. Thunderstorm season is sprite season.
"Sprites are a true space weather phenomenon," explains lightning scientist Oscar van der Velde of the Technical University of Catalonia, Spain. "They develop in mid-air around 80 km altitude, growing in both directions, first down, then up. This happens when a fierce lightning bolt draws lots of charge from a cloud near Earth's surface. Electric fields [shoot] to the top of Earth's atmosphere--and the result is a sprite. The entire process takes about 20 milliseconds."
Although sprites have been seen for at least a century, most scientists did not believe they existed until after 1989 when sprites were photographed by cameras onboard the space shuttle. Now "sprite chasers" routinely photograph sprites from their own homes. "I used up a Watec 910HX security camera with UFOCapture software to catch my sprites," says Popek. Give it a try!
diagram: How to Look for Sprites (used with permission of sky-fire.tv)
Realtime Sprite Photo Gallery
Realtime Aurora 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 May. 19, 2015, the network reported 13 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 May 21, 2015 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 |