NEW! STARLINK TRAIN ALERTS: You've probably heard about Starlink's "string of pearls" -- a bright train that forms in the night sky for a few days after the launch of each new batch of satellites. Now you can see one. Our Backyard Astronomy Alert Service now includes Starlink Train Alerts. You'll receive a text and email whenever a string of pearls is about to fly over your backyard. Sign up now.
WHAT IS GOING ON WITH THIS COMET? Last week, astronomers pointed their telescopes at Comet 10P/Tempel 2 for a special event. On July 20th, Earth crossed the comet's orbital plane, and we saw its dust trail edge-on as an exquisitely thin line. Dan Bartlett of June Lake, California, kept watching after the crossing--and he caught something unexpected:
In addition to the razor line of dust everyone else was seeing, Bartlett's deep images picked up a twisting, wave-like structure. It is reminiscent of waves in the narrow rings of Saturn caused by the gravitational shepherding of Saturn's moons.
Yet this comet has no moons. So what's going on? A likelier explanation involves geometry and the subtle difference between a comet's trail and a comet's tail.
The trail of 10P is what everyone was looking for--a pancake of ancient dust. This pancake takes centuries to form. Every time the comet swings around the sun, it leaves behind some heavy grains of dust. Eventually these grains settle into a narrow plane, which looks dramatic when you cross it.
The tail is completely different. This is a plume of fresh dust that emerges when the comet approaches the sun. It spews in its own direction and contains a lot of lightweight grains that get pushed around by sunlight.
A curved tail seen nearly edge-on might read as a ripple in the comet's otherwise flat trail.
Is that what Bartlett saw? There's one way to find out: More observations. Astronomers are encouraged to photograph 10P as we rise out of the comet's orbital plane. A changing point of view might reveal the dynamics and 3D shape of this apparent wave, and thus its true nature. Submit your images here.
Realtime 10P/Tempel Photo Gallery
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STERLING SILVER SPACE CAT PENDANT:Are you looking for a far-out gift? Consider the Sterling Silver Space Cat. On July 22nd, the students of Earth to Sky Calculus launched it to the stratosphere onboard a cosmic ray research balloon:
You can have it for $139.95. This feline astronaut is made of genuine sterling silver and hangs from a matching 18-inch sterling silver chain. It is a purrfect birthday, anniversary or belated graduation gift.
The students are selling space pendants to pay the helium bill for their cosmic ray ballooning program. Each one comes with a greeting card showing the jewelry in flight and telling the story of its trip to the stratosphere and back again.
Far Out Gifts: Earth to Sky Store
All sales support hands-on STEM education
Realtime Aurora Photo Gallery
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Realtime Space Weather Photo Gallery
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