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Fifty thousand years ago, the Sahara desert was wet and fertile. The Stone Age in Africa was just beginning and the world’s first sewing needle was invented. It was also the last time Comet C/2022 E3 (ZTF) passed by Earth.
The long-forgotten comet recently returned to Earth’s night sky, looking like a pale eraser spot that some even spotted with the naked eye in the darkest areas. It won’t be easy to catch a glimpse of it, but considering it’s your last (and first) shot, it might be worth a try.
Experts point to February 1 or 2, when the comet will pass closest to Earth, as the best time, but – with binoculars or a telescope – you can probably spot it now.
Comets are large bodies made of dust and ice. They orbit the sun in elliptical paths, speeding up as they approach perihelion (an object’s closest passage to the sun) and slowing down somewhat as they move toward the far outer reaches of the solar system.
Each comet has its own period, or the time it takes to complete an orbit and start a new one. Short-period comets may pass the sun once every 200 years or less. Said comets do not travel very far in the Solar System (usually only as far as the Kuiper Belt or a region just beyond Neptune) and begin their return journeys more quickly.
Other “long-period” comets can take up to 250,000 years to revisit the center of the Solar System. These intrepid bodies operate on orbits that take them to the far outskirts of the system—often 50,000 times farther than short-period comets. These long-period comets make up the Oort Cloud, or cluster of cometary debris at the periphery of the Solar System.
The frozen core of a comet, known as the nucleus, is usually less than 10 miles across. This is roughly the size of a small city or the volume of an extremely large mountain.
Comets heat up as they approach the sun. This causes some of the ice to be removed in gas. As the gas escapes from the comet, it may carry dust with it. The combined gas/dust patch engulfs the comet’s nucleus in a cloud known as a ‘coma’, then escapes in the form of a gently curving tail.
A second wake, known as the “ion tail”, which is associated with ultraviolet solar radiation causing electrons to jump out of coma, always points directly away from the sun due to the “solar wind”.
What’s the deal with Comet C/2022 E3 (ZTF)?
Comet C/2022 E3 (ZTF) was discovered by two astronomers on March 2, 2022. They used the Zwicky Transition Facility, an ultrasensitive camera attached to the Samuel Oschin Telescope at the Palomar Observatory in the Palomar Mountain Range in California.
At this point, it was an order of magnitude too faint to be seen with the naked eye (or even with ordinary telescopes). By November, it had brightened to the point that it was almost visible with the highest quality binoculars from dark areas. It has been found to have a period of about 50,000 years.
C2, or diatomic carbon (picture two carbon atoms bonded together), is believed to be present in the comet’s head. When excited by incoming solar radiation, it emits photons (packets of light) with wavelengths we see as green.
Where have you been all this time?
In a land far, far away. Until comets approach Earth and become bright enough for humanity’s most light-sensitive technology to spot a “new” unidentified object in the night sky, we simply cannot know of their existence.
A quick look at the comet from Central Virginia this morning. 150″ exposure time – shot between cloud breaks. Chances of seeing this with the naked eye increase significantly over the next week!
C/2022 E3 ZTFCanon RP, 400mm Mineral, VA 01/21/23 5:30am pic.twitter.com/f4aSi2Tb9t
— Peter Forrester ❄️💨❄️ (@forecaster25) January 21, 2023
Viewers in the Northern Hemisphere can look north in late January or early February. However, the comet is thought to peak at just slightly brighter than magnitude 6, which astronomers refer to as “barely visible”. This will be compounded by the waxing crescent moon, which will peak on February 5.
If you hope to catch a glimpse of its distant and muted splendor, find a dark spot away from city lights. Binoculars will probably do the trick, but you’ll also need some patience. A telescope would provide the clearest view.
Darker skies due to the weekend’s new moon may allow for sightings, but probably not with the naked eye.
In a few weeks, the comet will disappear from our sky the same way it appeared – with little fanfare. Based on its trajectory, the comet is believed to have a period of 50,000 years. However, there are simulations that show it could “escape” the solar system and essentially outrun the sun’s gravitational forces, which could mean it would never return – or at least not appear for millions of years.
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