Listen to radar echoes from satellites and meteors, live on listener-supported Space Weather Radio. | | | SLIGHT CHANCE OF STORMS: NOAA forecasters estimate a 10% chance of polar geomagnetic storms on Sept. 23rd. That's when a minor CME could deliver a glancing blow to Earth's magnetic field. Because the weeks around equinoxes favor auroras, even a weak impact could spark a nice display. Arctic sky watchers should be alert for Northern Lights. Aurora alerts: text, voice. CORONAL HOLE: NASA's Solar Dynamics Observatory is monitoring a coronal hole in the sun's northern hemisphere. It is the UV-dark region in this image taken during the early hours of Sept. 21st: The white lines in the image trace the sun's magnetic field. A coronal hole is a place where the magnetic field spreads apart, allowing solar wind to escape. A stream of solar wind flowing from this particular coronal hole is heading for Earth, due to arrive on Sept. 23-24. Its arrival could add to the impact of a minor CME expected to reach Earth at about the same time. Polar geomagnetic storms are possible early next week. Aurora alerts: text, voice. Realtime Aurora Photo Gallery NORTHERN AUTUMNAL EQUINOX: The September equinox occurs at 4:44 p.m. EDT (20:44 UT) on Sunday, Sept. 22nd, when the Sun crosses the equator heading south. This marks the beginning of autumn in the northern hemisphere and spring in the southern hemisphere. You know the equinox is near when you find yourself nearly-blinded while driving down east-west roads. Alan Friedman demonstrates the phenomenon from his hometown in Buffalo, New York: "At the equinoxes, the sun rises due east and sets due west on my street in Buffalo," says Friedman. "One has to drive carefully!" Other signs of the season may be found in the Space Weather Photo Gallery. Happy Equinox! Realtime Space Weather Photo Gallery Realtime Comet ISON Photo Gallery Realtime Noctilucent Cloud Photo Gallery [previous years: 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2011] 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 21, 2013 there were 1429 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 | |