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DOUBLE ASTEROID FLYBY: It's a cosmic coincidence. Two asteroids, each about 10 to 15 meters wide, will fly past Earth within hours of one another on Sept. 8th. Although both are coming inside the orbit of the Moon, there is no danger of impact. At closest approach, 2010 RF12 will be 77,000 km (0.2 LD) away; 2010 RX30 will be even farther at 231,000 km (0.6 LD). Advanced amateur astronomers may be able to track the asteroids using these ephemerides. The fast-moving space rocks will shine like stars of 15th or 16th magnitude. Good luck, observers!
MORNING CRESCENT: In case you overslept and missed it, today began with an exquisite waning crescent Moon. Abbas Ahmadian sends this dawn snapshot from Isfahan, Iran:
"[Here in Iran], we call this 'the old crescent of Ramadan,'" he says. Its sighting heralds the end of Ramadan, the 9th lunar month of the Islamic calendar.
Soon, Muslims around the world will observe Eid al-Fitr, a major holiday marking the end of Ramadan fasting. The start-time of Eid al-Fitr depends sensitively on the lunar phase--i.e., when the first crescent of the next cycle is sighted on Sept. 9th. Coincidentally, that same crescent will mark the beginning of Tishrei, the first month of the Hebrew calendar, and Jews will be celebrating their New Year (Rosh Hashanah). Seldom are so many eyes watching the Moon.
more images: from Mohammad Mehdi Asgari of Arak, Markazi, Iran; from Mahdi Noorafza of Isfahan, Iran; from Tamás Ábrahám of Zsámbék, Hungary; from Lyle Anderson of Duluth, MN; from Bryan Murahashi of San Jose, Ca; from Jim Schuyler of Washington D.C.
HURRICANE SEASON: "Sometimes the stormy seas surrounding solar active regions remind me of hurricanes... especially in September," says astrophotographer Alan Friedman of Buffalo, New York. "Here is a photo of swirling sunspot 1101, taken through a red H-alpha filter, but tinted ocean blue."
Ironically, this is not a very stormy sunspot. The well-ordered, spiral magnetic field that so resembles a hurricane turns out to be remarkably stable. Sunspot 1101 has not emitted the slightest peep of a solar flare in more than two weeks.
A truly stormy sunspot looks more like this. Sunspot 1105, now approaching the sun's northwestern limb, has a fractured core surrounded by a profusion of smaller spots. Magnetic fields of opposite polarity are popping up and bumping together, causing the active region to crackle with B- and C-class solar flares. Readers, if you have a solar telescope, point it at the sun's northwestern limb. Hurricane season is underway.
August 2010 Northern Lights Gallery
[previous Augusts: 2009, 2008, 2007, 2006, 2005, 2004, 2003]
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 7, 2010 there were 1144 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 site_images of the Sun from SOHO. |
| ||from the NOAA Space Environment Center |
| ||from the National Solar Data Analysis Center |