Solar Ejection Blows Away Tail of Approaching Comet

A new comet making its way toward the Earth got a dose of the sun's true power when a gust of solar wind blew away its tail.

The comet, named C/2023 P1, or Nishimura, has continued to approach the inner solar system since it was first spotted on August 11 by Japanese amateur astronomer Hideo Nishimura, and is expected to be visible to the naked eye by early to mid-September.

As it grew closer to the sun this week, it was buffeted by solar winds, disrupting its characteristic tail, spaceweather.com reports.

"A comet is like a dirty snowball," Keith Horne, a professor of astronomy at the University of St. Andrews in Scotland, told Newsweek earlier this year. "Comets and planets both orbit the sun, but unlike the circular orbits of planets, comets follow highly elliptical orbits."

As the comet moves toward the sun, it's followed by a trail of dust and ice released as it heats up.

"This leaves it with lots of loose particles, both charged and neutral, that come away from it while it is moving," Ian Whittaker, a senior physics lecturer in physics at Nottingham Trent University in the U.K., previously told Newsweek. "The neutral particles come off in a cone behind the comet as it moves—a bit like being behind a big truck on the motorway while it's raining, all the excess water hits whatever is directly behind it."

"The charged particles will do the same unless there are any electric or magnetic fields nearby," Whittaker said. "The sun itself has a magnetic dipole (like the Earth) and has a magnetic field flowing out into the solar system. So the charged particles coming off of the comet are picked up by this magnetic field and sent directly away from the sun (anti-sunward)."

The comet was walloped by a coronal mass ejection—or CME—from the sun on September 2, ripping away its tail from its head in what's known as a "disconnection event," according to spaceweather.com.

The exact mechanism behind this event is still unclear to astronomers, but solar wind in the form of CMEs appears to be involved. The CME that hit the comet this week was likely emitted from active sunspot AR3413, which is facing toward the comet.

The comet's tail has already grown back, but may be knocked off again as it faces more CMEs in coming weeks.

Nishimura is due to approach its closest point to the Earth on September 12, at a distance of 27 million miles. Around a week later, on September 17, the comet will pass closest to the sun and appear at its brightest in the night sky, in the constellation Virgo.

The comet is predicted to be visible to the naked eye in the coming days: as of September 4, the comet had a magnitude of around 6, which is the threshold for being seen without visual aids like binoculars or a telescope. Lower positive magnitudes and larger negative magnitudes translate to brighter objects, with Venus having a magnitude of -5, and the full moon -13. Nishimura is expected to brighten to a magnitude of 2 or 3 by the time it reaches its closest point to the sun.

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