Here’s how to watch the green comet

  • Astronomers recently discovered a green comet approaching Earth for the first time in 50,000 years.
  • Comet ZTF may never return, so we could be the last people to see it.
  • Here’s how, where and when to see the comet as it passes Earth in late January and early February.

We could be the last people ever to see a green comet hurtling past Earth from the outer reaches of the solar system in late January and early February.

C/2022 E3 (ZTF), or comet ZTF for short — the name astronomers gave this space snowpack after it was discovered by the Zwicky Transient Facility in March — hasn’t been in our cosmic neighborhood since the last ice age.

The researchers calculated that the icy ball of gas, dust and rock orbits the Sun roughly every 50,000 years, meaning that Neanderthals were still walking the Earth and humans had just migrated out of Africa for the first time when the comet last passed by.

Without telescopes or binoculars, these ancient peoples may not have spotted the comet at all. And there may never be a chance to see him again.

“Some predictions suggest that this comet’s orbit is so eccentric that it’s no longer in orbit — so it’s not going to come back at all and just keep going,” Jessica Lee, an astronomer at the Royal Greenwich Observatory, told Newsweek.

So it might be worth your while to look for Comet ZTF and become one of the few people to ever see it up close. Here’s what you need to know to maximize your chances.

When to see the green comet

A man observes the stars with a telescope

You may need a small telescope to spot Comet ZTF, but binoculars may be sufficient.

Bryan Allen/Getty Images

In the Northern Hemisphere, the green comet should be visible just before dawn in late January, according to NASA. Amateur astronomers have already started photographing the green comet to show what you can see.

A fully eclipsed new moon could provide ideal dark skies for spying comets on January 21.

Then, in early February, the comet will be visible in the southern hemisphere.

Comet ZTF will pass about 26 million miles from Earth — as close as it will come — on February 2. That’s nearly 109 times the average distance to the Moon, but the comet burns so brightly that it might still be visible in the night sky.

The comet is expected to be brightest on Jan. 31 and Feb. 1, though the moon will be bright, and the comet will be “the faintest object visible without optical aid in a very clear, very dark sky,” according to Adler. Planetarium.

It is important to prepare for success if you are trying to spot it.

How to spot the green comet

At first, spotting Comet ZTF may require a telescope, but as it approaches Earth, viewers will be able to see it with binoculars or even the naked eye.

“Comets are notoriously unpredictable, but if this one continues its current brightness trend, it will be easy to spot with binoculars, and it’s quite possible that it could become visible to the naked eye under dark skies,” NASA wrote in a Dec. 29 update.

For the best viewing, choose a cloudless night and get away from the city lights, into the darkest sky possible. When the moon is weak, or at least when it is below the horizon, the sky will be even darker.

If you’re near an urban area, you may want to bring binoculars or even a telescope, in case the lights obscure the comet to the naked eye.

Where in the night sky to look for comet ZTF

Look at the right stars to see a green comet. According to, the comet is currently visible passing through the constellation Boötes, near its border with Hercules. It is heading towards Polaris — the North Star — and will be visible near the star on January 30. It will appear earlier in the evening as it approaches Polaris.

“It will probably be different from other stars because it will look a little dim compared to other stars,” Thomas Prince, director of the WM Keck Institute for Space Studies at Caltech, told FOX Weather.

In the Southern Hemisphere, on February 10, the comet will be about 1.5 degrees from Mars, according to Prince. It’s about the width of your little finger when held outstretched. If you can locate Mars shining in the sky, look for a comet around it.

EarthSky publishes maps that help you locate reference objects — Hercules, Polaris and Mars — in the night sky.

Why is the comet green?

The comet has a “greenish coma, a short broad dust tail, and a long faint ion tail,” according to NASA.

Many comets glow green. Laboratory research has linked this aura to a reactive molecule called dicarbon, which emits green light as sunlight decays.

Dicarbon is common in comets, but is not usually found in their tails.

That’s why the coma — the haze surrounding the ball of frozen gas, dust and rock at the center of the comet — glows green, while the tail remains white.

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