June 15, 2020: Here we go again. A comet is falling toward the sun, and it could become a naked-eye object after it skims past the orbit of Mercury on July 3rd. Michael Mattiazzo photographed Comet NEOWISE (C/2020 F3) on June 10th from Swan Hill, Australia:
“Pushing the limits of comet observing, I had to leave home to find a clear horizon,” says Mattiazzo. “When I took the picture, Comet NEOWISE was very close to the sun and only 5 degrees above the local horizon. Its visual magnitude was near +7.0, below the threshold for naked-eye visibility.”
It might not look like much now, but this comet could blossom in the weeks after perihelion (closest approach to the sun). Forecasters say Comet NEOWISE could become as bright as a 2nd or 3rd magnitude star. Northern hemisphere observers would be able to easily see it in the evening sky in mid-July.
At this point, readers may be experiencing a feeling of déjà vu. Almost the exact same forecast was issued for Comet ATLAS (C/2019 Y4) in March and Comet SWAN (C/2020 F8) in May. Both comets dived toward the sun and … instead of blossoming, died. Intense solar heat can do that to a fragile ball of ice.
Mattiazzo, who is one of the world’s most experienced amateur comet observers, thinks Comet NEOWISE could turn out better. “I’d say there’s a 70% chance this comet will survive perihelion,” he says, basing his guess on the stability of the comet’s light curve, which sets it apart from Comets ATLAS and SWAN. “Comet NEOWISE could be a case of third time lucky.”
We’ll know soon enough. On June 22nd, the comet will enter the field of view of SOHO‘s C3 coronagraph–a space-based instrument that blocks the glare of the sun to reveal nearby stars, planets and comets. For a whole week, astronomers will be able to monitor Comet NEOWISE as it approaches the orbit of Mercury. If it falls apart, the event may be visible in the images. Ditto if it survives.
Stay tuned for updates.