Newly discovered comet ZTF is making its closest approach to Earth in 50,000 years, becoming visible to the naked eye and making big headlines. Some are calling it a “super rare” and “bright green” comet, but will it live up to the hype? we explain.
Comet ZTF Facts
Comet ZTF was discovered on March 2, 2022 by a robotic camera attached to a telescope known as the Zwicky Transient Facility (ZTF). Palomar Observatory in Southern California. ZTF scans the entire northern sky every two days and captures hundreds of thousands of stars and galaxies in one frame. Many comets have been found with this instrument. The latest is cataloged as C/2022 E3 (ZTF), Comet ZTF for short.
Why Is It Rare?
Comet ZTF has traveled 2.8 trillion miles and will make its closest approach to Earth in 50,000 years on February 1, 2023. Orbital calculations indicate that comet ZTF will never return.
What makes ZTF a Green Comet?
The greenish color is probably due to a molecule made of two carbon atoms bonded together dicarbon. This unusual chemical process occurs mostly in the head, not the tail. If you look at Comet ZTF, that greenish color may be very faint (if it’s visible at all). The appearance of green comets due to dicarbon is extremely rare.
Recent images show that the head (coma) is distinctly green and trailed by an impressively long, thin blush appendage (tail). But a long exposure camera sees it. The color will appear less green to the naked eye.
When and where to see Comet ZTF
From the second half of January to the beginning of February, the ZTF can be bright enough to be seen with the naked eye. Use a reliable star map to track night-to-night changes in position relative to background stars and constellations. Here are the dates and approximate locations.
See the constellation Corona Borealis before sunrise.
See the constellation Boötes before sunrise.
The comet will be visible in the night sky (previously it was only visible in the morning). Look north, above and to the left of the Big Dipper.
Look next to the Dragon (Dragon) constellation.
Look a few degrees east of the Little Dipper bowl. By the evening of the 27th, orange Kochab, the brighter of the two outer stars in the bowl of Ursa Minor, will be about three degrees warmer to the upper right.
Look at Polaris.
Look next to the constellation Camelopardalis.
See the bright yellow-white star Capella (from Gemini).
Look inside the triangle known as the “Children” star pattern in Aurigada around 8pm local time.
Look two degrees to the upper left of Mars.
Note: If you live in a large city or remote town, seeing this comet will be difficult – if not impossible. Even for those with a dark and starry sky, ZTF can be a bit difficult to find.
Watch Comet ZTF live now:
More Information About Viewing ZTF
As for the tail, comets can shed two types of dust and gas. Dust tails are brighter and more spectacular to the eye than goose tails because dust is a very effective reflector of sunlight. The most spectacular comets are dusty and can produce long, bright tails that make them awesome and impressive celestial spectacles.
Goosetails, on the other hand, look duller and glow with a blue color. The gas is activated by the Sun’s ultraviolet rays, causing the tail to glow in the same way that black light causes phosphorescent paint to burn. Unfortunately, the gas tails produced by most comets appear long, thin, and quite faint; impressive in photos but visually weak. This is what we are currently seeing with ZTF.
Finally, in late January and early February, when the ZTF is at its brightest, it will have to compete with another celestial object: the Moon. In the same time frame, the Moon will be near full phase (The Full Snow Moon February 5). A full Moon shining like a giant spotlight in the night sky will make it even more difficult to try to see a relatively dim and diffuse object like comet ZTF.
Other Visible Comets
There are about a dozen comets that can be seen in the night sky. But most of them are visible only with medium-large telescopes. To actually see any of these, you’ll need a good star atlas and accurate coordinate positions to know where to point your instrument. Many enthusiasts who seek them out call such comets “faint darks” because of what they look like through the eyepiece: a faint, fuzzy blob of light. These are known as “common comets”.
Once in a while, perhaps two or three times in 15 or 20 years, a bright or “great comet” will arrive. These are the species that thrill those without binoculars or a telescope—where all you have to do is step outside, look up, and exclaim, “Oh, look! that!“Such comets are larger on average. Most of these have a nucleus or core less than two or three miles wide. But there are others that can be several times larger.
As a rule, the closer a comet is to the Sun, the brighter it is. The giants that sweep closer than Earth’s distance to the Sun (92.9 million miles) are quite bright. Good examples are comet Hale-Bopp in the spring of 1997 and comet NEOWISE in the summer of 2020 (discovered by a robotic space telescope).
So what category does ZTF fall into? In many ways, it’s pretty much an ordinary comet, but compared to most other faint nebulae, ZTF is quite bright.
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Will you be watching the skies for the “green” comet ZTF?
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