AURORA ALERTS: Did you miss the Northern Lights of June 25th? Next time get a wake-up call from Space Weather PHONE.

EVENING PLANETS: Tonight, after sunset, go outside and look west. Saturn, Mars and the crescent Moon are gathering in the form of a scalene triangle: sky map. If you have a backyard telescope, scan the vertices for the rings of Saturn, the little red disk of Mars and a panorama of lunar mountains and craters; it's a nice way to wrap up the weekend.

LAVENDER SUN: When the sun turns purple, watch out. Something is on fire. "Tonight as the sun was setting in the smoke from the Santa Barbara Gap fire, it turned a purplish color," says John Boyd, who sends this picture from southern California:

Purple suns appear when the air is filled with smoky particles measuring about 1 micron (10^-6 m) across. Such particles scatter red light strongly, while allowing bluer light to pass through. This filtering action in the smoke over Santa Barbara produced a lavender hue reminiscent of the great Alberta muskeg fires of September 1950.

These colorful suns are beautiful, says Boyd, "but I hope the firefighters, who are doing a great job at protecting the homes here, will be able to put out the fire soon." [update]

more images: from Joan Barnett of Goleta, California

SOUTH POLE AURORAS: Imagine walking a mile to work every day in pitch-black dark with air temperatures routinely dipping below -90 F. It might be worth it if you could look up and see this:

Photo details: Canon Rebel XTi 400D, ISO 1600, 10mm lens, 10s, f4.0

The picture comes from Earth's south pole where "we had a nice display of aurora australis on July 5th," says J. Dana Hrubes, science leader of the Amundsen-Scott Station. Just before he took the picture, the interplanetary magnetic field (IMF) near Earth tipped south, opening a crack in our planet's magnetosphere. Solar wind poured in and fueled the auroras. "That's Jupiter shining just above the silhouette of the South Pole Telescope," he points out.

Every day, Hrubes walks a mile from the main station to the telescope. "This gives me plenty of time to gaze at the sky. The temperature was -84 F when I took today's pictures and I have taken photos down to a temperature of -110.7 F, which is my personal all time low in early August, 2005. You have to take photos as quickly as possible; you never know what is going to freeze first, your camera or your fingers." (Note to cold-weather photographers: Hrubes uses a Canon 400D.)

"We are now getting into the coldest months, July and August, where we will see temperatures below -100 F," he continues. "These are actual static temperatures, not wind chills. Furthermore, the elevation of the site is nearly 10,000 feet and we experience physiological altitudes between 10,500 ft and 12,200 ft during winter." Many people would be put off by such conditions, but not Hrubes. "In four years at the Pole, I have racked up more than 3,000 miles of walking. I am lucky to have a great walk like this to my job 7 days a week."

2008 Noctilucent Photo Gallery
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