If you follow science media at all, there is a good chance that you have heard of the infamous “Green Comet”. Known as C/2022 E3 (ZTF), this comet has grabbed the attention of many astronomers, citizens, and the media in the span of mere weeks.
What the media doesn’t tell you is that the comet is not as special as you might anticipate.
Of course, C/2022 E3 (ZTF) is still special in the aspect that it’s a comet – something unusual to search the sky for. The majority of the amateur astrophotography community takes long exposures of galaxies, star clusters, and nebulae; it’s rare that they’re treated to the sight of a near-Earth comet such as C/2022 E3 (ZTF).
For those wondering what C/2022 E3 (ZTF) is: the comet is essentially a frozen ball of ice, dust, and other debris and chemicals that originated from the Oort Cloud. It was discovered in March of 2022 by the Zwicky Transient Facility (hence the name ZTF), and was observed to be around 4.3 AU away from the Sun. At the time of discovery, the magnitude (a fancy way of saying “overall brightness”) of C/2022 E3 (ZTF) was 17.3, so it was rather faint and ironically, the comet wasn’t the main focus of the astronomical community (although it was continually and occasionally monitored by observatories globally).
By November of 2022, the comet had seen a rapid increase in brightness (it had hit magnitude 10). Astronomers and astrophotographers globally began to see observations of C/2022 E3 (ZTF) in the late evening and early winter mornings, and more and more telescopes were pointed at the comet. By December, the comet had developed a coma with a green hue (due to the reactions with carbon and cyanogen from the comet nucleus with the rays emitted from the Sun), a faint ion tail, and a broad dust tail. The news began the big hype: making promises of “a once-in-a-lifetime comet that was going to be visible from Earth”, stirring hopes of a second NEOWISE occurrence of space enthusiasts around the globe.
The comet reached perihelion (the closest distance to the Sun) on Jan 12th, 2023 – only a mere 1.11 AU away. The magnitude of the comet was rapidly brightening to the low 5s, and the naked-eye observations of the comets began pouring in from dark skies around the globe. As the comet began to melt, many distinct features such as a long antitail and an ion-tail disconnection event occurred, and many passionate astrophotographers photographed such events. Then, the closest occurance to Earth (at the distance of 0.28 AU away) was seen in early February 2023.
This news may be fascinating and in fact “once-in-a-lifetime” type news, but don’t get your hopes up. Most viewers from the cities will most likely not be able to see the comet due to high light pollution in developed countries. Similarly, only those with extremely sharp vision may be able to make out the comet as a diffuse, green smudge in the night sky. Otherwise, don’t get your expectations up. However, the comet can be best observed with good binoculars or a telescope.
C/2022 E3 (ZTF) is no comet NEOWISE, and will most likely fade away as it gets further from Earth back to its Oort Cloud origins at the very edge of the solar system. However, many astronomy enthusiasts have made memories and permanent photographs of the comet as it gave its 50,000 year greeting to Earth. Luckily, the large community of astrophotographers have provided viewers clouded in or overpowered by the city lights an experience to see the comet by themselves through photos.
As C/2022 E3 (ZTF) makes its trek away from Earth, humanity can only hope for another bright comet easily visible to the naked eye before the return of the famous Halley’s Comet in 2065.
The photograph of C/2022 E3 ZTF on the article is by me. I took it using a Nikon D90 and a Gear 80mm telescope, tracked on a Sky-Watcher SWSA 2i.