Comet Nishimura: How and When to See It This Weekend

Astronomy aficionados are buzzing about a bright new comet. The ball of dust and ice is formally named C/2023 P1, but is also called Comet Nishimura, for Hideo Nishimura, the Japanese photographer who first spotted it. And you may have an opportunity to see it as well during the next few nights.

How was the comet discovered?

Mr. Nishimura captured the comet on Aug. 12 while imaging the sky before sunrise with a digital camera — the third comet he has discovered. He reported the sighting to the Central Bureau for Astronomical Telegrams, which alerted astronomers around the world.

Vishnu Reddy, a planetary scientist at the University of Arizona who received the alert, was surprised that an amateur observer had found it.

“The era of some random individual finding comets is thought to be long gone,” Dr. Reddy said, because most comets are detected by automated surveys conducted by professionally run observatories on Earth and in space. That’s exactly how scientists discovered Comet NEOWISE in 2021, which was named for the NASA space telescope that detected it, the Near-Earth Object Wide-field Infrared Survey Explorer.

But when astronomers dug through past data, they found observations that included Comet Nishimura but which, for some reason, had not set off their automated systems. That might be because many professionally managed telescopes are based in the Southwest, Dr. Reddy said, where clear desert skies make viewing excellent for most of the year — except for the late summer monsoon season, around the same time Comet Nishimura is reaching its peak brightness.

How can I see the comet?

According to Dr. Reddy, the best time to catch Comet Nishimura is over the coming mornings. Its brightness will peak over the weekend and into Monday’s sunrise, rivaling that of the North Star. You can use binoculars or a telescope for an even better view.

To see Comet Nishimura, first go to a location where you can clearly see the eastern horizon, without any trees or other barriers in the way. Over the ocean, atop a high-rise building or up in the mountains are great sites, Dr. Reddy said.

To find the comet in the sky, set up shop about an hour and a half before sunrise, and look for a small streak to the lower left of Venus, a bright orb in the east just above the horizon. Another way to track down the comet is to look to the left of Regulus, a bright star in the constellation Leo.

After Sept. 11, Comet Nishimura will dip below the horizon and be more difficult to find in the evening sky because of the brightness of the sunset, Dr. Reddy said.

What will the comet look like?

A comet’s atmosphere contains a molecule called dicarbon, or two carbon atoms bound together. When dicarbon breaks down, it produces a green glow. People around the world have already shared stunning images of Comet Nishimura’s emerald hue.

But Dr. Reddy advised managing your expectations about what you might see if you go out to look for it. “Don’t go out early in the morning looking for a giant comet,” he said, because the really impressive photos are taken with specialized equipment. Instead, expect to see a small streak, about an inch from head to tail, low on the horizon.

Regardless, Dr. Reddy said part of the magic was that it was a once-in-a-lifetime view. Nishimura’s orbit around the sun takes about 435 years. That means that the last time Comet Nishimura flew by Earth was in 1588. And though professional astronomers will be able to see it with telescopes for some time before it disappears, it won’t swing back around for the average skywatcher to see until 2458.