A heavenly spectacle not seen since the Stone Age graces the night sky, giving stargazers a chance. Comet Tsuchinshan-ATLAS, also known as C/2023 A3 or simply Comet A3, has emerged as one of the most spectacular naked-eye comets of the year.
As the sun dipped below the horizon on Tuesday evening, October 15, sky enthusiasts were in for a treat. This is the second of two prime viewing opportunities for northern hemisphere observers to witness this cosmic visitor at its brightest.
How Long Will Comets Be Visible?
Comet A3 will technically be visible at the end of October, but its brightness will decrease each day as it moves away from Earth. So, going out on a Tuesday night gives you the best chance to see it.
The comet came close to Earth on Saturday, a dizzying 44 million miles away. However, it is difficult to find because it stays close to the sun.
Spencer Heaps / FR172046 AP
Perihelion – the closest point to the sun – occurs on September 27, according to EarthSky. After orbiting the sun, comets are often brighter, with longer tails, as the heat from the sun evaporates ice from the surface, sending it into space.
How Fast Do Comets Move?
Comets move very fast. Really fast. According to data from NASA’s Jet Propulsion Laboratory, Comet A3’s maximum orbital speed is 150,000 miles per hour.
Comets reach their highest speeds when they are closest to the sun, as our star exerts its maximum gravitational pull on the dirty snowball.
As the comet moves away from the sun, it will slow down, but it will still move very quickly. However, the orbital period of Comet A3 is 80,000 years. That’s because it’s a long way to travel—out to the Oort Cloud, a minimum of 2,000 astronomical units (AU) away from the sun. For context, one AU is about 93 million miles.
Where To Look For Comets At Night
To catch a glimpse of our heavenly guest, you need to look west about 45 minutes after sunset where you are. The comet will be about 46 million miles from Earth and should be visible above the western horizon.
The comet will set about an hour and 40 minutes after its first appearance.
Because the moon is almost full on Tuesday, the sky will be slightly brighter, which could make the comet more difficult to see. That said, the moon should shine in the southern part of the sky, so as not to disturb the spectacle too much.
You’ll need clear skies to see the comet, so check your local weather forecast to see if you’re getting a shot.
How to Read Comet A3 Night
The comet will have a magnitude of +0.9 tonight, according to Forbes, meaning it will be visible to the naked eye. For reference, the northern star has a magnitude of about 2, meaning the comet is more than twice as bright as the famous celestial compass point.
For the best view, use a pair of binoculars or, if you’re lucky enough to have one, a telescope.
Finding a high place will keep the comet above the horizon longer, and moving to a dark place away from the light pollution of city lights will also help.
What is a Comet?
Comets are icy remnants from the beginning of our solar system, made up of dust, rock, and frozen gas. While often imagined as fiery objects streaking across the sky, comets only develop beautiful glowing tails as they approach the sun.
As it approaches the sun, the heat causes the ice to evaporate, releasing gas and dust that form a glowing coma and a long tail that can reach millions of miles into space.
In their original state, before heating, comets can range in size from just a few miles to dozens of miles. But if these materials begin to sublimate and expand near the sun, they can appear larger than other planets.
NASA estimates that there are billions of comets orbiting in the Kuiper Belt, the region of icy objects beyond Neptune, and even further out in the Oort Cloud, which is home to the most distant and ancient objects like Comet A3.
New comets are discovered every year. However, many burn up when they approach the sun or remain too far away to be seen without a special telescope.
Some well-known comets from recent history include Neowise in 2020 and Hale-Bopp and Hyakutake in the 1990s. In 2023, a rare green comet that hasn’t visited Earth in 50,000 years is approaching our planet, presenting a spectacular spectacle to sky watchers.
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