An icy visitor from the far reaches of the solar system is expected to shoot past Earth and the sun in the coming weeks and it might be visible with the unaided human eye. This visitor from afar is a comet believed to have brushed by Earth before - some 50,000 years ago.
Discovered in March 2022, the comet recently passed within Jupiter’s orbit and is heading for the inner solar system. Our witnessing the flyby soon to occur could be a once-in-a-lifetime astronomical occasion.
Bright Enough for Naked Eyesight?
Dubbed C/2022 E3 ZTF, the comet displays a greenish coma, the nebulous envelope surrounding a comet’s nucleus, and a yellow-tinged tail of dust and ion particles in its wake.
Initially showing a stellar magnitude of 17 when it was discovered, according to EarthSky, C/2022 E3 ZTF’s brightness will increase as it approaches the sun, as the frozen matter of a comet’s nucleus sublimates when exposed to solar radiation sometimes causing a spectacular green “glow.”
Just today the comet reached its perihelion, its closest distance from the sun, and currently shines with a magnitude of 7.4—The lower an object’s magnitude the greater its brightness. It’s magnitude is expected to increase to 5 or 6, the range visible to the naked eye, next month when it reaches its closest distance from Earth.
So with dark skies and minimal moonlight or streetlight, C/2022 E3 ZTF might be seen without binoculars or a telescope. However, comets are notoriously unpredictable; it could be even brighter.
The comet grows brighter as it speeds toward the sun. (Courtesy of Jose Francisco Hernandez)
C/2022 E3 ZTF exhibits a green coma and yellow-tinged ion tail. (Courtesy of Jose Francisco Hernandez)
Optimal Viewing Geometry
Typically, as comets near the sun, they are drowned out by sunlight and banished from sight but unlike other comets C/2022 E3 ZTF’s trajectory presents great geometry for viewing from Earth. Appearing slightly past midnight over the coming weeks, it will stay visible despite its proximity to the sun—This holds true for stargazers in the northern hemisphere at least.
Originally appearing in the north, the comet arced northwest to southwest and then seemed to loop as our vantage point on Earth changed while we orbited the sun. The comet then shot northward in early October, vanishing entirely from view for comet watchers in the southern hemisphere.
C/2022 E3 ZTF is currently careening toward the Northern Crown and by month’s end will have neared Polaris, all the while getting brighter and closer to Earth. It will become visible to viewers south of the equator again in early February when it pops above their northern horizon.
The comet will reach its closest distance from Earth on Feb. 2 and you can find it transiting in between the constellations Draco and Camelopardalis just south of Polaris. As it travels in a retrograde orbit (the opposite way as Earth’s orbit), it will be moving very quickly. Try spying it with your naked eye, otherwise use a pair of good binoculars.
As for the size of this comet, its nucleus was measured to be about 1 kilometer across, according to AFP—relatively small compared to more famous comets such as NEOWISE, which appeared in 2020; more famously, Hale-Bopp appeared in 1997 exhibiting a diameter of 60 miles (37 kilometers). But what C/2022 E3 ZTF lacks in size, it compensates for in closeness.
Comet C/2022 E3 ZTF presents optimal geometry in its trajectory, facilitating excellent viewing opportunities from Earth. (Courtesy of Jose Francisco Hernandez)
C/2022 E3 ZTF grows brighter as it approaches its perihelion, closest distance from the sun. (Courtesy of Jose Francisco Hernandez)
Having just reached its perihelion today, the comet now lies roughly 103 million miles (1.11 AU/166 million kilometers) from the sun. When it “grazes” by Earth on Feb. 2, it will be 27 million miles (0.29 AU/42 million kilometers) away, before it swerves outbound toward the outer solar system again.
This is the first time said comet has entered our solar system since the Upper Paleolithic period 50,000 years ago. Scientists say it could be permanently ejected once it makes its departure from the solar system, AFP reported.
But before we bid farewell, it offers an encore.
A Date With Mars … And Adios
Particularly for first-time comet spotters, C/2022 E3 ZTF presents a great sighting opportunity on Feb. 10 when it will appear extremely close to Mars. You can try taking a long-exposure photo for 20 to 30 seconds which might yield a fuzzy, tailed object beside the rust-red planet.
As for where C/2022 E3 ZTF is headed, we might ask where it came from. The comet is believed to originate from the Oort Cloud, a theoretical vast sphere that surrounds the solar system inhabited by mysterious icy objects.
The comet is set to near Mars as it makes its departure from the inner solar system. (Courtesy of Jose Francisco Hernandez)
As for the comet’s unwieldy name, here’s the story behind that. It was first discovered during a survey on March 2, 2022, by astronomers Bryce Bolin and Frank Masci using the Zwicky Transient Facility (ZTF), located at Mt. Palomar in Southern California. Its name denotes the facility where it was discovered (ZTF), the year of its discovery (2022), and that it was the third (3) such object found in the year’s fifth half-month (A, B, C, D, E), hence C/2022 E3 ZTF.
This visitor from afar will vanish from view by late April 2023.