Comet 3I/ATLAS has sprouted an unusual tail
After passing behind the sun in late October, interstellar Comet 3I/ATLAS is now visible from Earth again. Astronomers are photographing it in the pre-dawn sky (constellation Virgo).
The sum image from 24x35sec green and 2x35 red and 2x35 blue with 11"
RASA shows a 5' coma and 4-5 tails or jets: 400“ pa 0, 500” pa 316, 900“
pa 295, 430” pa 278 and a counter-tail 200" pa 109 At the time of
exposure, the comet was 7-10° above the horizon; at the end, twilight
interfered with the observation, which took place under bright
moonlight. We observed from a mountain location.
The comet was 9m1 bright (measured from 6x35 sec green).
Michael Jaeger of Austria has been tracking the comet since it re-appeared on Nov. 4th. "We have something unusual to report," he says. "3I/ATLAS showed a complex tail structure early this morning (Nov. 8th)."
"At the time of exposure, the comet was only 7-10° above the horizon," he says. "At the end, twilight interfered with the observation, which took place under bright moonlight. We observed from a mountain location."
This image differs from other photos we've seen in recent days, which show only a fuzzy blob with no distinct tail. Jaeger's exposure detected a spray of four or five tails, including a narrow jet pointing toward the sun.
Harvard astronomer Avi Loeb suggests that 3I/ATLAS might be a spaceship. If so, this could be a sign of propulsion; after all, engines make plumes.Yet, there is no sign that 3I/ATLAS has changed course. Jaeger found it exactly where it should be, following the same cometary trajectory it was on before perihelion.
"The astrometry showed that it continues to follow the ephemeris," notes Jaeger. "The residuals were better than 1 arc second. It hasn't slowed down or released any small spaceships."