HAPPY SOLSTICE: The northern summer solstice arrived this morning, June 21st at 5:14 a.m. EDT. This is when the sun is farthest north for the year and begins its six-month return southward. Today is the first day of summer the Northern Hemisphere, the first day of winter in the Southern Hemisphere. Happy solstice! Solar flare alerts: SMS Text.
SPACEX MYSTERY, SOLVED: The mystery of SpaceX's "rocket powered auroras" has been solved. On Sunday morning, June 19th, SpaceX launched a Falcon 9 rocket from Cape Canaveral. Photographers accustomed to seeing these launches were surprised when something unusual appeared. A red glow stretched across the Milky Way. It looked like the aurora borealis, as shown in this photo from Christopher Hoffman in Saint Mary's County, Maryland:
"I went out with some first time photographers to teach them how to set up their cameras for night sky photography," says Hoffman. "We took a 30 second exposure, and when the exposure was finished I saw this red glowing area covering the Milky Way."
Photographers in New York, Ohio, North Carolina and Tennesee saw it, too. The glow appeared about 10 minutes after the Falcon 9 rocket lifted off, and many observers likened its appearance to auroras. However, there was no geomagnetic storm in progress. It had to be the rocket.
What happened? Space physicist Jeff Baumgardner of Boston University has the answer: "This glow is probably the exhaust gasses from the rocket's 2nd stage causing the ionosphere to recombine quickly. This is a well studied phenomenon when rocket engines are firing in the altitude regime 200-250 km."
Above: A similar display of red light appeared over the eastern USA following the launch of a Titan IV rocket on April 30, 2005. [full story]
In simplified form, here is what happens: The upper atmosphere is filled with oxygen ions (O+). Of particular interest is the F-layer of the ionosphere, because it is rich in O+. When the Falcon 9 rocket reaches the F-layer, it adds water (H2O) and carbon dioxide (CO2) to the mix, spewing the molecules out of its engine. Oxygen ions are hungry for electrons, and the newly arriving molecules are eager to provide them. Electrons "re-combine" with oxygen, turing ions into atoms. As electrons cascade down the oxygen atom's energy levels, they emit red photons at a wavelength of 6300 Å--the same color as red auroras.
more images: from Josh Thum of Sevierville, Tennessee; from Brenda Calinawan of Kortright, New York; from David Cortner of Rutherford College, NC
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"I LOVE YOU FOREVER" MOONSTONE PENDANT: Are you looking for a far-out gift? Consider the "I Love You Forever" Moonstone. This one hitched a ride to the stratosphere onboard a cosmic ray research ballooin on May 13, 2022:
You can have it for $162.95. The moonstone's sterling silver infinity wrap is inscribed with the words "I love you forever." It makes a great anniversary or birthday gift. The moonstone comes with a greeting card showing the pendant in flight, telling the story of its trip to the edge of space and back again.
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