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SPINNING ASTEROID FLYBY: Newly-discovered asteroid 2011 GP59 is flying past Earth today, April 15th, not far beyond the orbit of the Moon (1.4 LD). There's no danger of a collision, but the 50-meter space rock is remarkable: It is elongated and spinning once every 7.5 minutes. This causes the asteroid to flash like a strobe light. A video taken by Joe Pollock of Appalachian State University on April 11th shows the effect nicely. Experienced amateur astronomers using mid-sized telescopes can watch 2011 GP59 strobe through the constellations Virgo and Hydra tonight with a peak brightness near 13th magnitude. [3D orbit] [ephemeris] [JPL press release] [more images: #1, #2]
STRING OF PEARLS: No, it's not a fleet of alien spacecraft. Nor is it a disintegrating comet, although the resemblence to Shoemaker-Levy 9 is striking. What could it be? Play the video, make your best guess, then scroll down for the answer.
What you just saw was sunlight glinting off a line of ten geosynchronous satellites stretched over Rigikulm, Switzerland, on March 5th. One by one, the illuminated satellites flare and then subside as they enter the shadow of our planet.
"The 'string of pearls' phenomenon is best seen during early-spring nights when the declination of the sun is equal to that of the geosychronous orbit, e.g. -7o as measured from Switzerland," says photographer Roland Stalder. "This short video sequence (130 images at 25 fps) is part of an all-night timelapse with 1630 images, where over 50 geosynchronous satellite flares can be found. A FullHD BlueRay disk can be ordered though me."
SOLAR ACTIVITY HEATS UP: No, it's not your imagination. Solar activity really is picking up, bringing an end to a century-class solar minimum. Get the full story from Science@NASA.
APRIL AURORAS: The auroras this month have been something to shout about. Just ask this happy sky watcher, photographed by Ruslan Akhmetsafin in Siberia on April 13th:
The display came at the tail end of a geomagnetic storm sparked by solar wind hitting Earth's magnetic field on April 12th. The event was so strong, it sent Northern Lights spilling over the Canadian border into US states such as Michigan and Minnesota. It could happen again on April 18-20 when another solar wind stream is expected to reach our planet. Prepare to shout! Aurora alerts: voice, text.
April 2011 Aurora Gallery
[previous Aprils: 2010, 2009, 2008, 2007, 2006, 2005, 2004, 2003, 2002]
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 April 15, 2011 there were 1218 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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