HALLOWEEN FIREBALLS ARE SCARIER THAN WE THOUGHT: Right now, Earth is passing through a stream of debris from Comet Encke--source of the annual "Halloween Fireballs." These slow-moving meteors streak from the constellation Taurus during weeks around Halloween. If you see one tonight, it could foreshadow something genuinely scary. New peer-reviewed research suggests that hazardous Tunguska-class objects may be lurking within the stream--and Earth could run into one in the 2030s. Happy Halloween?
RAPID BRIGHTENING OF COMET 3I/ATLAS: Spacecraft monitoring the sun witnessed a dramatic surge in the brightness of Comet 3I/ATLAS as it plunged toward its Oct. 29th perihelion. Qicheng Zhang (Lowell Observatory) and Karl Battams (U.S. Naval Research Laboratory) reported the phenomenon in a preprint submitted to the Astrophysical Journal Letters on Oct. 28th.
"The reason for 3I’s rapid brightening, which far exceeds the brightening rate of most Oort cloud comets, remains unclear," the authors say.
While Earth-based telescopes lost sight of the comet during its close approach to the sun, coronagraphs on spacecraft like STEREO-A, SOHO, and NOAA’s GOES-19 satellite never stopped watching. The composite image, above, shows how the comet looked to these instruments.
NOAA’s CCOR-1 coronagraph did the best job resolving the comet, showing a 4-arcminute-wide coma (atmosphere), while SOHO's C3 coronagraph collected the best color data, revealing the comet to be bluer than the sun. The blue color hints that glowing gas, not dust, now dominates its brightness.
Zhang and Battams analyzed coronagraph data from September and October. They found that 3I/ATLAS has been increasing in brightness as the 7.5th power of decreasing distance from the sun--twice as fast as it was brightening earlier this year. This might be caused by a surge in water sublimating from the comet's core, they speculated in the paper.
"Our cursory analysis of this data indicates the comet will likely emerge from solar conjunction considerably brighter than when it entered," they say.
This bodes well for the future. Europe's JUICE spacecraft will encounter the comet for a closer look starting Nov. 2nd. Its instruments will benefit from the increased brightness. Moreover, telescopes on Earth will regain the ability to image 3I/ATLAS in late November and December when the interstellar object fully emerges from the glare of the sun.
What will they see? Stay tuned for updates!
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DRINK LIKE A STORM TROOPER: It's the perfect gift for a Star Wars fan--a Storm Trooper Whiskey Decanter. On Oct. 10th, it hitched a ride onboard a cosmic ray research balloon floating 106,066 feet above the Sierra Nevada mountains of central California:
You can have it for $124.95. The 750 ml decanter comes with a greeting card showing the item in flight, and telling the story of its journey to the stratosphere and back again. All purchases from the Earth to Sky Store help pay the helium bill for our student ballooning program.
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