VOLCANIC GASES REACH THE STRATOSPHERE AGAIN: For the second time this year, a volcano has injected sulfurous gases into the stratosphere. NASA satellites find that emissions from the Ulawun volcano in New Guinea reached the stratosphere on Aug. 3rd, following a similar eruption from the Raikoke volcano in the Kirul Islands on June 22nd. This latest ejection of SO2 could produce volcanic sunsets in the tropics and the southern hemisphere for months to come.
LATE-SEASON NOCTILUCENT CLOUDS: The northern summer seasoon for noctilucent clouds (NLCs) is coming to an end, but it's not over yet. Arctic sky watchers are still seeing occasional electric-blue ripples in the twilight sky. Claire Sayers sends this picture from northern Sweden:
"These night shining clouds appeared about an hour after midnight on August 16th," she says. "I photographed them using my digital camera, a 15s exposure at ISO 200."
Although NLCs are a polar phenomenon, polar sky watchers seldom see them. The summer midnight sun interferes with visibility. As summer comes to an end, northern skies are darkening, allowing for midnight sightings in places like Sweden. If you live in a high-northern location, be alert for NLCs as August comes to and end--and submit your images here.
Realtime Noctilucent Cloud Photo Gallery
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AN UNUSUAL FORM OF AURORA: You've heard of auroras--green and purple lights that dance in the sky during geomagnetic storms. But have you ever heard of an SAR? Stable Auroral Red arcs (SARs) were discovered in 1956 at the beginning of the Space Age and have been recorded by cameras on satellites hundreds of times since. Most aurora watchers have never seen an SAR, though, because they are usually invisible to the human eye. On Aug. 5th, Harlan Thomas caught one over Peyto Lake in Alberta, Canada:
"I could not make it out with the naked eye," says Thomas, "but my camera captured the broad red arc in a 30 second exposure (ISO 3200). It meandered very slowly across the sky for hours, motions that distinguished it from ordinary green auroras visible in the sky that night." This sequence of images shows how the red arc lazily moved around: #1, #2, #3, #4, #5, #6, #7, #8.
SARs are related to auroras, but they are not the same. Regular auroras appear when high-energy particles rain down along polar magnetic field lines, hitting the atmosphere (100-200 km high) and causing it to glow like the picture tube of an old color TV. SARs form differently. They are a sign of heat energy leaking into the upper atmosphere (~400 km high) from Earth's ring current system.
SARs can become visible to the naked eye during strong geomagnetic storms. The geomagnetic storm of Aug. 5th, however, was not strong, thus requiring long camera exposures to reveal the arc.
Realtime Space Weather Photo Gallery
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APOLLO 11 PROOF SILVER DOLLARS: The students of Earth to Sky Calculus weren't even born when Neil Armstrong and Buzz Aldrin landed on the Moon in 1969 years ago. Nevertheless, they "get it." On July 20th, the students launched 50 Apollo 11 silver dollars to the stratosphere onboard a cosmic ray balloon. The coins touched the edge of space 50 years to the day after Neil and Buzz made footprints in the Sea of Tranquillity:
You can have one for $197.95. The students are selling these coins to support their cosmic ray ballooning program. Quantities are limited and more than half have already been sold. Each one comes with a greeting card showing the item in flight and telling the story of its journey to the edge of space.
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