When is the best time to see auroras? Where is the best place to go? And how do you photograph them? These questions and more are answered in a new book, Northern Lights - a Guide, by Pal Brekke & Fredrik Broms.
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MORNING CONJUNCTION: Mars, the 1st-magnitude star Regulus, and Comet ISON have gathered together in the pre-dawn sky only a few degrees apart. Comet ISON is invisible to the naked eye, but Mars and Regulus are bright enough to see without optics. They form a pretty red-blue "double star" that can lead telescopic observers to the comet. Sky maps: Oct. 13, 14, 15.
M-CLASS FLARE, EARTH-DIRECTED CME: October 13th began with an explosion on the sun. At 00:43 UT, sunspot AR1865 erupted, producing an M1-class solar flare and an Earth-directed CME. NASA's Solar Dynamics Observatory captured the explosion's flash of extreme UV radiation:
Soon after the flare, the Solar and Heliospheric Observatory recorded a faint CME emerging from the blast site. Based on the approximate speed of the expanding cloud, between 600 km/s and 800 km/s, it will probably reach Earth on Oct. 15-16. Polar geomagnetic storms are possible when the CME arrives. Aurora alerts: text, voice.
MORSE CODE BEAMED INTO SPACE: When NASA's Juno spacecraft flew past Earth on Oct. 9th, ham radio operators around the world took part in a global effort to communicate with the spacecraft. Organized by the Juno mission team and JPL, the hams slowly tapped out "Hi" in Morse code: . In New Mexico, amateur radio astronomer Thomas Ashcraft was observing the heavens with his own shortwave radio telescope when he heard the transmissions:
"The patterned keying from amateur radio operators was noted clearly on my radio telescope," says Ashcraft. "In the dynamic spectrum, shown above, it is the series of horizontal 'dots' just above 28 MHz." Listening to this seven minute extract of the signal pattern sent to Juno takes patience, so Ashcraft sped up the recording by 10 times. "Here it is," he says.
Juno listened for the message using its onboard WAVES instrument, a radio and plasma wave sensor designed to study magnetic storms at Jupiter. Did Juno actually hear anything? The Juno mission team wrote this on the event's home page: "Thank you amateur radio operators. This activity is now concluded. The Juno team hopes to share the results with you soon."
Realtime Space Weather Photo Gallery
CHANCE OF FLARES: A pair of sunspots pointing almost-directly at Earth poses a threat for strong solar flares. NASA's Solar Dynamics Observatory photographed the two active regions, AR1861 and AR1865, on Oct. 12th:
Sunspot AR1865 has a 'beta-gamma-delta' magnetic field that harbors energy for X-class solar flares, while AR1861 has a 'beta-gamma' magnetic field capable of powering M-class eruptions. NOAA forecasters estimate a 40% chance of M-class flares and a 15% chance of X-flares on Oct. 12th. Solar flare alerts: text, voice.
GREEN COMET ISON: Comet ISON is brightening as it approaches the sun. At the moment it is glowing like a 10th magnitude star, too dim for naked-eye viewing but an easy target for many telescopes on Earth. "This is what the comet looked like on Oct. 8th using the 0.8m (32 inch) Schulman Telescope," reports Adam Block from the University of Arizona Skycenter atop Mount Lemmon:
ISON's green color comes from the gases surrounding its icy nucleus. Jets spewing from the comet's core contain diatomic carbon (C2) and cyanogen (CN: a poisonous gas found in many comets). Both substances glow green when illuminated by sunlight in the near-vacuum of space.
"I am certain more images of Comet ISON will be coming out shortly as it increases in brightness during its dive towards the Sun," adds Block. "Here is hoping it survives that rendezvous on Nov. 28th and emerges as something spectacular on the other side!"
Although the comet is very faint, finding it is easy. Comet ISON rises alongside Mars in the eastern sky just before dawn. Amateur astronomers, if you have a GOTO telescope, enter these coordinates. Special dates of interest include Oct. 13-15 when Mars, Comet ISON, and the first magnitude star Regulus will be clustered in a patch of sky less than 3o apart. Red Mars and blue Regulus will form a beautiful naked eye "double star" in the early morning sky. Sky maps: Oct. 10, 11, 12, 13, 14, 15.
Realtime Comet ISON Photo Gallery
Realtime Aurora Photo Gallery