A rare green comet is passing through the night sky on Feb 1st

Jan 21, 2023

On February 1st, a comet named C/2022 E3 (ZTF) with a bright green color will come close to Earth for the first time in 50,000 years. It will pass by at a distance of 26 million miles (42 million kilometers) from Earth, providing a unique night sky view that hasn't been seen since the time that modern humans roamed the Earth alongside one of the many extinct human species, the Neanderthals. 

However, you don't have to wait until February to catch a glimpse of the comet, as it is already visible in the sky during late night and early morning. Stargazers have been tracking the comet's path for several weeks and had a great view of it on January 12th when it made its closest approach to the sun, a maneuver known as perihelion.

Here’s everything that we know about the green comet so far.

C/2022 E3 was first detected by astronomers in March 2022, when it was traveling through the solar system at a distance of 399 million miles (642 million km) from the sun, within the orbit of Jupiter. At that time, it was relatively faint, about 25,000 times fainter than the dimmest stars visible to the naked eye. However, researchers were able to make out a distinct tail or coma, which confirmed that it was a comet, not an asteroid. Asteroids are made of rock, while comets are made of ice and dust particles that vaporize as they approach the sun, creating a visible tail. Both asteroids and comets orbit around the sun.

By January 12th, 2023, the comet had moved much closer to Earth, about 300 million miles (482 million km) closer, and was visible in the night sky near the northern constellation of Corona Borealis. Since then, it has continued moving westward across the sky. According to experts, the comet will be visible to the naked eye by the third week of January, and it should be easy to spot if you have a clear view of the sky and you know where to look for it.

On the nights of January 26th and 27th, the comet may be visible just east of the Little Dipper's bowl. By February 1st, when the comet makes its closest approach to Earth, it will appear near the constellation Camelopardalis, in close proximity to the Big Dipper. These are approximate locations, and the comet's position in the sky may vary slightly due to its motion. It's always recommended to check with local observatories or sky maps for the most accurate and up-to-date information.

Around February 5th and 6th, a few days after its closest approach to Earth, the comet will move across the night sky to the west of the star Capella and then it will appear to enter the constellation Auriga. After that, it will continue moving down towards Taurus, becoming increasingly faint as it moves away from Earth, and back out towards the edge of the solar system. 

Why is this comet green?

The comet itself is not naturally green, but its head appears to emit a green glow due to a rare chemical reaction. The green coloration is likely caused by diatomic carbon (C2), which is a simple molecule comprised of two carbon atoms bonded together. When ultraviolet light from the sun causes this molecule to decay, it emits a green glow that can persist for numerous days. This is according to a study published in the Proceedings of the National Academy of Sciences in 2021.

This unique green light does not reach the comet's tail, or coma, which is made of gas. The gas in the coma is created by solar radiation, specifically, sunlight causes the comet to sublimate, or change from a solid to a gas without passing through the liquid phase. This gas creates the tail that streams behind the comet, which is often seen as blue in color due to the ultraviolet light.

Unfortunately, if you live in the southern hemisphere, there’s no guarantee that you’ll get to see the comet until its closest approach to Earth. Thereafter, it’ll be visible in the South for a short while before fading from view. We don’t know when this comet will return, but it likely won’t be within the lifetime of anyone alive today.


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  1. Straspey said on January 22, 2023 at 3:47 pm

    “Why is this comet green?”

    In reality – this is not a comet – but actually a massive balloon filled with Green Slime.

    Scientists have discovered a small leak in the giant balloon – which explains its green tail – as some of the slime oozes out while the “comet” travels through space.

    Observers hope to pinpoint the exact date and time when the giant balloon will enter the earth’s atmosphere – spilling its load of Green Slime over entire populations.

    The event will be simulcast on both the Cartoon Network and SyFy television channels.

    Check your local listings.

  2. VioletMoon said on January 22, 2023 at 3:43 am

    Imitating CNET, but CNET provides earlier coverage, a superior story and a spectacular photo.

    The next story, much later because all the news on gHacks is much later:

    “Musk says higher priced Twitter subscription won’t carry ads.”

    Wait and watch.

  3. Tachy said on January 22, 2023 at 2:27 am


    Please reply personally to this so we know you are a human and not an AI.

    Why did you post about space on a computing blog?

    1. John G. said on January 22, 2023 at 1:37 pm

      The ‘post and forget’ awesome strategy. How nice is doing nothing and have a rest afterwards.

  4. Anonymous said on January 21, 2023 at 9:16 pm

    Basic science – the world spins. Visible from where and when may have been useful to those who read ghacks in hope of seeing a story about space objects that may or may not be visible.

    PLEASE stay on topic. It doesn’t matter if it is basic computing but it should be relevant.

  5. Shawn said on January 21, 2023 at 9:01 pm

    If it’s radiating green that thing is full of copper.

    Unless it’s Kryptonite then well better hope it’s one of the good guys we have enough issues here on earth already. =D

    Oh and if it’s a big emerald well it can crash in my backyard no problems with that ;-)

  6. Oxa said on January 21, 2023 at 8:24 pm

    A rare green non sequitur of a blog post emits from Shaun.

  7. Panguila said on January 21, 2023 at 8:19 pm

    WalframAlpha claims that ‘C/2022 E3’ will be over my area from 2am, now whether that equates to acctually being able to see it with the naked eye is something to be determined

    I recall looking up at the night sky to witness a faint object hurtling in one direction only to suddenly ricochet at angle toward another direction, as if it bounced off an invisible wall, it might have been an asteroid getting at taste of the Earth’s atmosphere or just me hallucinating

    astrological phenomina are a sight to behold

    1. gh said on January 22, 2023 at 7:15 am

      Hi, kindly explain how I can search the same on wolframalpha.

      1. Panguila said on January 22, 2023 at 2:34 pm

        in the search bar on WolframAlpha, type in ‘C/2022 E3 (ZTF) above the horizon (followed by your location ‘city, country’)’, the result that I got is that it is ‘currently’ in the Draco constellation, it also details what time Draco will be visible and what direction it will be in (the coordinate direction you should be facing, to take the guess work out of that I just downloaded a stargazing app such as Stellarium, Sky Walk 2, Night Sky)

        you do not actually need to do any of this because there are charts of the comets trajectory available online, C/2022 E3 (ZTF) is currently transiting in the region of the sky where the ‘Draco’ constallation is, the trick is finding the ideal day and time to view the specticle at your location (WolframAlpha details this), some people are just going to have to wait until it is viewable for them because the constellation might be in daylight at their location, which would not be the ideal conditions to view the comet

        I missed it yesterday but I can still catch it after 2 am when Draco begins to rise over the horizon

  8. John G. said on January 21, 2023 at 8:05 pm

    It brings us Windows 12.

  9. chesscanoe said on January 21, 2023 at 7:52 pm

    I assume this post was an error, intentional or not, and will be deleted as soon as possible.

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