The newly discovered comet ZTF is closing in on 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.
ZTF Comet Data
Comet ZTF was discovered on March 2, 2022 by a robotic camera attached to a telescope known as the Zwicky Transient Facility (ZTF) in the Palomar Observatory in southern california. ZTF scans the entire northern sky every two days, capturing hundreds of thousands of stars and galaxies in a single shot. Many comets have been found with this instrument. The most recent is listed as C/2022 E3 (ZTF), Comet ZTF for short.
Because it’s weird?
Comet ZTF has traveled a distance of 2.8 trillion miles and will make its closest approach to Earth in 50,000 years on February 1, 2023. Orbital calculations suggest that Comet ZTF may never return.
What makes ZTF a green comet?
The greenish color is probably due to a molecule made up of two bonded carbon atoms, called dicarbon. This unusual chemical process is mostly confined to the head, not the tail. If you look at comet ZTF, that greenish tint is likely to be quite faint (if it’s visible at all). The appearance of green comets due to dicarbon is quite rare.
Recent images show that the head (comma) appears to be distinctly green and is followed by an impressively long and slender blushing appendage (the tail). But that’s what a camera taking a long exposure sees. The dye will look much less green to the naked eye.
when and where to see comet ztf
During the latter part of January through early February, ZTF can become bright enough to be visible to the naked eye. Use a reliable star chart to track night-to-night position change relative to background stars and constellations. Here are the approximate dates and locations.
January 12-14
Look up at the Corona Borealis constellation before sunrise.
January 14-20
Look up at the Bootes constellation before sunrise.
January 21st
The comet will be visible in the night sky (previously only visible in the early morning hours). Look north, above, and to the left of the Big Dipper.
January 22-25
Look near the constellation Draco (The Dragon).
January 26 and 27
Look several degrees east of the Ursa Minor bowl. On the night of the 27th, it will be about three degrees to the upper right of orange Kochab, the brighter of the two outer stars in the bowl of Ursa Minor.
January 29-30
Look towards Polaris.
february 1st
Look near the constellation Camelopardalis.
February 5th
Look up at the bright yellow-white star Capella (of the constellation Gemini).
February 6th
Look inside the triangle known as “The Kids” star pattern in Auriga, directly overhead at around 8pm local time.
Feb. 10
Look two degrees to the upper left of Mars.
Note: If you live in a big city or suburb, spotting this comet will be a difficult, if not impossible task. Even for those blessed with dark, starry skies, finding ZTF could be a challenge.
Watch the ZTF Comet live now:
Learn more about viewing ZTF
As for the tail, comets can spew two types, made up of dust and gas. Dust tails are much brighter and more spectacular to the eye than gas tails, because dust is a very effective reflector of sunlight. The most spectacular comets are dusty and can produce long, bright tails, making for amazing and impressive celestial spectacles.
Gas tails, on the other hand, appear much fainter and glow a bluish hue. The gas is activated by the Sun’s ultraviolet rays, causing the tail to glow in the same way that black light makes phosphorescent paint glow. Unfortunately, the gas tails produced by most comets appear long, stringy, and rather wispy; Impressive in photographs but disappointing visually. And that’s what we’re currently seeing with ZTF.
Finally, when the ZTF is at its brightest in late January and early February, it will have to compete with another celestial object: the Moon. During that same period of time, the Moon will be close to the full phase (The snow full moon is February 5). Blazing in the night sky like a giant spotlight, the full Moon will make trying to see a relatively dim and diffuse object like the ZTF comet even more difficult.
Other visible comets
There are almost a dozen comets available to view in the night sky tonight. However, most of these are visible only with moderately large telescopes. You’d also need a good star atlas, as well as precise coordinate positions so you know where to point your instrument to actually see any of these. Most hobbyists who make an effort to look for them call these comets “faint fuzzys” because that’s more or less what they appear through the eyepiece: a dim, fuzzy smudge of light. These are known as “common kites”.
Every once in a while, maybe two or three times in a span of 15 or 20 years, a bright “big comet” will appear. These are the types that thrill us without binoculars or telescopes, the type where all you have to do is step outside, look up, and exclaim, “Oh look.” that!Such kites tend to be much larger than average. Most of these have a center or core less than two or three miles in diameter. But there are others that can be up to several times larger.
As a general rule, the closer a comet gets to the Sun, the brighter it gets. The large ones that sweep closer than Earth’s distance from the Sun (92.9 million miles) tend to be quite bright. Good examples are the Hale-Bopp comet in the spring of 1997 and the NEOWISE comet (discovered with a robotic space telescope) in the summer of 2020.
So which category does ZTF fall into? In many ways it’s a fairly ordinary kite, but compared to most other faint fuzzies, ZTF is extremely bright.
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