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THE SUN IS FLATLINING: For the 5th day in a row, solar activity remains very low. No sunspots are flaring, and the sun's X-ray output has flatlined. NOAA forecasters estimate a scant 1% chance of X-flares and a 10% chance of M-flares on Feb. 17th. Solar flare alerts: text, voice
NORTHERN LIGHTS: Auroras are dancing around the Arctic Circle as the leading edge of an approaching solar wind stream presses against Earth's magnetic field. "We had a really nice display around 9 pm local time on Feb. 16th," says Nick James, who sends this picture from Kiruna, Sweden:
The stage is set for more outbursts like James saw. Why? The interplanetary magnetic field (IMF) around Earth is tipping south, an arrangement that can open a crack in our planet's magnetosphere. If the incoming stream of solar wind pours through that crack, voila!--bright auroras. NOAA forecasters estimate a 35% chance of geomagnetic storms on Feb. 17th. Aurora alerts: text, voice
Realtime Aurora Photo Gallery
VENUS AND MARS: Venus and Mars are converging for a beautiful close encounter in the sunset sky. On Feb. 21st, the two planets will be so close together that sky watchers might lose Mars in Venus's glare. Last night, Eliot Herman photographed the pair, still relatively far apart, over Tucson, Arizona:
"There were light clouds in the fading sunlight," says Herman. "Bright Venus had a rainbow ring from the translucent cloud while the sky surrounding it was clear enough to let the stars and Mars shine through."
In only a few days, the two planets will be dramatically closer together. Their minimum separation on Feb. 21st, only 0.4o, is less than the width of a full Moon. The night before closest approach might be best of all: On Feb. 20th, the crescent Moon will pass right by the converging planets. Mark both dates on your calendar, Feb. 20th and 21st, and watch the western sky at sunset. It's a great way to end the day.
Realtime Space Weather 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 Feb. 17, 2015, the network reported 9 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 February 17, 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 |