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BRIEF GEOMAGNETIC STORM: A minor geomagnetic broke out during the early hours of Sept. 19th and quickly subsided again. The cause was a fluctuation in the interplanetary magnetic field (IMF). The IMF near Earth tipped south, opening a crack in our planet's magnetic defenses against the solar wind. So far no reports of bright auroras have been received, probably because of the brevity of the event. Aurora alerts: text or voice
INCOMING CME COULD SPARK EQUINOX AURORAS: Sunspot 2415 erupted on Sept.18th, and although the resulting C-class flare was minor, it did hurl a CME toward Earth. The Solar and Heliospheric Observatory recorded the expanding cloud as it raced away from the sun:
The CME is traveling mostly south of the sun-Earth line. Nevertheless, the cloud's northern flank could deliver a glancing blow to our planet's magnetic field on Sept. 21st, less than two days before the northern autumnal equinox.
This is potentially good news for sky watchers because, for reasons researchers do not fully understand, auroras love equinoxes. At this time of year even gentle gusts of solar wind can spark a nice display of Northern or Southern Lights.
NOAA forecasters estimate a 50% chance of polar geomagnetic storms on Sept. 21st when the CME arrives. Aurora alerts: text or voice
Realtime Aurora Photo Gallery
INCREDIBLE NEW PHOTOS OF PLUTO: NASA is still downloading images from the Pluto flyby two months ago. Some of the new arrivals, like this one received on Sept. 13th, are causing researchers to question what they thought they knew about the distant dwarf planet:
New Horizons snapped the picture looking back at Pluto about 15 minutes after its closest approach on July 14th. Backlit by the sun, Pluto's rugged, icy mountains tower over a vast frozen plain extending to the horizon. The backlighting highlights more than a dozen layers of haze in Pluto's tenuous but distended atmosphere.
The new pictures provide evidence for a remarkably Earth-like "hydrological" cycle on Pluto – but involving soft and exotic ices, including nitrogen, rather than water ice. There are signs of hazes, evaporation, precipitation, and flowing glaciers similar to the frozen streams on the margins of ice caps on Greenland and Antarctica.
"We did not expect to find hints of a nitrogen-based glacial cycle on Pluto operating in the frigid conditions of the outer solar system," says Alan Howard, a member of the mission's science team from the University of Virginia. "Driven by dim sunlight, this would be directly comparable to the hydrological cycle that feeds ice caps on Earth, where water is evaporated from the oceans, falls as snow, and returns to the seas through glacial flow."
"Pluto is surprisingly Earth-like in this regard," adds Alan Stern, principal investigator of the New Horizons mission, "and no one predicted it."
Realtime Space Weather Photo Gallery
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Realtime NLC 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 Sep. 19, 2015, the network reported 11 fireballs.
(11 sporadics)
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 September 19, 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 |
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