New comet might be a bright one
On March 2, 2022, astronomers discovered a new comet. It’s still far from the sun, at a distance of 4 astronomical units (AU, or Earth-sun units of distance). But when it comes nearest the Earth and sun, in late 2022 and early 2023, the comet should become easily visible in binoculars.
Astronomers have labeled this comet C/2022 E3 (ZTF). It got its name because it was the third such object to be discovered in the fifth half-month (a, b, c, d, E) of this year. The ZTF stands for the Zwicky Transient Facility, which uses the 48-inch Samuel Oschin robotic telescope, located at Mt. Palomar in southern California.
Comet C/2022 E3 (ZTF) was announced in Central Bureau Electronic Circular No. 5111. The orbital elements were calculated and presented. The comet will reach its closest point to the sun, its perihelion, on January 13, 2023. At that time, it will be 1.11 AU (1.11 Earth-sun units of distance) from the sun.
The comet will reach its closest point to the Earth, 0.29 AU which is 27 million miles (44 million km), on February 2, 2023. It isn’t yet known if this comet has visited the inner solar system in the past. More observations and calculations will be required to determine that.
The tilt of the orbit to our path around the sun is steep and retrograde, meaning the comet goes around the sun in the opposite direction than do the planets.
This means it will, at some point, move quickly through our sky.
Finally, the comet enters our solar system from the north, and on February 12, passes to the south of our orbital plane. This means it will be better observed from the Northern Hemisphere until then, after that the Southern Hemisphere is favored.
Interesting #comet confirmed:
C/2022 E3 (ZTF)
After perihelion on Jan 13, 2023 it approaches earth to 0.29 AU on Feb 2. By then it may be brighter than magnitude 6 while conveniently located for N. hemisphere observers in Camelopardalis.
MPEC 2022-F13 and https://t.co/a7m73XRPFh pic.twitter.com/MDEuGcGxNd— Gideon van Buitenen (@giddgvb) March 21, 2022
The discovery story
Comet C/2022 E3 (ZTF) was in the morning sky, in the direction of the constellation Aquila the Eagle, when astronomers with the Zwicky Transient Facility first spotted it.
The ZTF program images the whole Northern Hemisphere every two nights looking for supernovae, variable stars, binary stars, flashing merging neutron stars, asteroids, and comets. It has discovered 10 comets in the past three years, and half of them carry the acronym ZTF in their names. One, discovered a year ago, was named C/2021 E3 (ZTF). Similar name, but don’t confuse the two comets. Today, we are talking about the 2022 one!
At its March 2022 discovery, this comet was a very faint 17th magnitude. Initially, it appeared as a stellar object, that is, as a dimly shining point. But, unlike the stars, whose distances make their motions undetectable except via special techniques, this object was moving in front of the stars.
Newly discovered objects that are found to be moving are placed on the Minor Planet Center’s NEO Page. That’s how other astronomers know to image and hopefully thereby confirm the object. As both professional and amateur astronomers do find the new object, and submit more positions for it to the Minor Planet Center, a preliminary orbit can be determined. In the case of this object, it looked more like a comet orbit than an asteroid’s orbit. That is, the path around the sun was oblong and not circular.
At that point, the object was placed on the Possible Comet Confirmation Page which begged for astronomers to image it to see if it had a coma or extended atmosphere, surrounding the object’s nucleus or core. Why is that important? It’s important because virtually all asteroids – which tend to be rocky or metallic – appear starlike (the name asteroid means “starlike). But an icy comet will form a halo, or coma around its nucleus as the material on the nucleus heats up, as the comet moves inward toward the sun. Only several high-magnification images, stacked to increase contrast, will show the coma of a faint comet.
Three teams imaged this new object, and they did find a coma.
What path will C/2022 E3 (ZTF) take through our sky?
Comet C/2022 E3 (ZTF) has favorable geometry with respect to the earth. Normally a comet will pass near the sun’s vicinity and the elongation, which is the angle in degrees between the sun and the comet as seen from the earth, grows small and the comet disappears in the sun’s glare for a few weeks. Not this one! It stays in the dark sky for most of its trip through the inner solar system, even when it passes from the evening sky to the morning sky at 44 degrees north of the sun on November 21.
Northern Hemisphere observers will have a view of the comet until the end of April 2023, when the comet, then a telescopic object, will disappear into the evening twilight.
Southern Hemisphere observers will have a good view of the comet until early October when it will disappear into their evening twilight as it rapidly heads northward. They will get their next view of the comet in early February 2023, when it pops above their northern horizon.
Many grand photo opportunities
Comet 2022 E3 (ZTF) will pass only a degree from M27, the Dumbbell Nebula on May 31, 2022. The comet will approach to within a quarter of a degree of the double star Albireo in the constellation Cygnus on June 17.
A week later it’ll pass a quarter degree from the globular cluster, M56. And, on July 4, it’ll pass half of a degree from the Ring nebula, M57.
During this time, the comet will be faint, about magnitude 13, but imagers should be able to pick up the comet. By the time it passes 2.5 degrees south of the Hercules Globular Cluster, M13, on August 23, it will be heading south into the constellation Corona Borealis. From here it makes a U-turn, then it heads rapidly north. When expected to be at its brightest in late January 2023, the comet will be high in the evening northern sky in the area where the constellation Auriga is located.
How bright will the new comet get?
The path of the comet is well-determined, so we know where the comet will be in our sky. As for brightness, comets are unpredictable. As the nucleus warms up, it will often do so unevenly, and the brightness over time can change without warning. Having said that, what would the average comet do? At this point, that is the best we can do in predicting the brightness, or magnitude, of the comet.
Below is a graph showing the potential light curve for the comet. Along the bottom of the graph is the date, while along the side of the graph we find the magnitude. Magnitude is measured as such: the smaller the number the brighter the object appears. To be seen with the unaided eye a comet has to reach about magnitude five, to be visible in binoculars it has to reach magnitude nine.
As we can see from this graph, the comet will be visible in many amateurs’ telescopes in September, as it reaches magnitude twelve. At that time, the comet will be in the northern evening sky, in the part of the sky where the constellation Hercules is located. By mid-December, the comet will become visible in binoculars. Observers can see the comet in the morning sky, located in the part of the sky where the constellation Corona Borealis is located.
At its brightest, the comet may attain visibility to the unaided eye in late January 2023.
Bottom line: New comet 2022 E3 (ZTF) is headed towards the inner solar system. In early 2023, it should be easily visible in binoculars as it graces our skies. Check back with EarthSky for updates as the comet approaches its perihelion. And submit your images to EarthSky’s community page.
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