A green comet that's speeding toward the inner solar system will soon make its closest approach to the sun. Here's how you can watch the "cosmic snowball" live as it zooms past our star.
Comet C/2022 E3 (ZTF) is set to reach perihelion—the point in the orbit of an astronomical object at which it is closest to the sun—on Thursday. It is now possible to observe it through telescopes in the constellation Corona Borealis, and the comet could soon be visible to the naked eye if current predictions turn out to be true.
The comet was discovered last March by the Zwicky Transient Facility, an astronomical survey conducted by California's Palomar Observatory, and will be located around 103 million miles from the sun by the time of its perihelion.
Comets are astronomical objects made up of frozen gases, dust and rock that orbit the sun. Sometimes referred to as cosmic snowballs, these objects are blasted with increasing amounts of radiation as they approach our star releasing gases and debris.
This process forms a glowing atmosphere around the comet, known as a coma—which in the case of C/2022 E3 (ZTF) is green—and two vast tails of gas and dust. The gas tail is sometimes referred to as the "ion" or "plasma" tail because it consists of charged particles.
The Virtual Telescope Project (VTP)—a service provided by the Bellatrix Astronomical Observatory in Ceccano, Italy, that operates and provides access to robotic, remotely operated telescopes—is hosting a live stream that will show the comet speeding through space around the time of its perihelion.
The live feed is scheduled to begin at 4 a.m. Universal Coordinated Time on Friday and will last about an hour. That's equivalent to 11 p.m. Eastern Time and 8 p.m. Pacific Time on Thursday.
Gianluca Masi, an astronomer and director of the VTP, told Newsweek he would be using the project's "most advanced" robotic unit to capture footage for the livestream. He said the telescope's gaze will focus on the region around the comet's nucleus.
"We will concentrate on the inner coma, the region just around the nucleus," Masi said. "We should see any possible jet there, potential dust shells as well as the inner portion of the ion tail. We will be using our scientific imaging camera, which provides black and white images."
He continued: "Comet C/2022 E3 (ZTF) is a very easy target for our systems—the available advanced robotic mounts are used to track extremely fast-moving objects, both natural and man-made."
After the comet's perihelion, it is scheduled to make a close approach to Earth on February 1, when it will reach a minimum distance of around 26 million miles from our planet.
The VTP will be providing a second livestream of the comet on this date, beginning at 11 p.m. Eastern Time or 8 p.m. Pacific Time. On the second live feed, Masi plans to use a wider lens to capture more of the ion tail, as well as a color-imaging camera.
Once the comet has reached perihelion, it will start speeding away from the sun and the inner solar system. What happens next, though, is unclear because of uncertainties regarding its future trajectory. Some data indicates that the comet might never return to the inner solar system, given the shape of its orbit.
"We don't have an estimate for the furthest it will get from the Earth yet—estimates vary—but if it does return it won't be for at least 50,000 years," Jessica Lee, an astronomer at the Royal Observatory Greenwich in the United Kingdom, said.
Astronomers are predicting the comet could be faintly visible with the naked eye under ideal conditions by January's second half if current trends continue. But they urge caution, given that predicting the brightness of comets is notoriously difficult.
"Given the brightening trend we are seeing, at the time of close approach to Earth, Comet C/2022 E3 (ZTF) should be as bright as magnitude +5.0-5.5, so within the range of naked-eye visibility under dark skies," Masi said.
"The last part of the night should be preferable to observe it [at this time], as the bright moon will set, leaving a bit of dark sky to see the comet at its best," he said.
While the comet will most likely not be visible with the naked eye by the time of perihelion, it will easily be within the range of basic binoculars, Masi said.
Correction 01/11/23, 11:45 a.m. ET: This article was corrected to make clear the day of the comet's perihelion.
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