Comet visible over Logan, first time in 80,000 years

If Utahns glanced west during sunset between 6 and 8 p.m. there’s a chance they saw comet C/2023 A3 Tsuchinshan-ATLAS, a rare astronomical sight visible above the horizon between Oct. 12 – 24. 

The comet was discovered in January of last year. It hasn’t been this close to Earth for 80,000 years and will take that long to come back again, making the sight a once-in-a-lifetime opportunity. 

This comet is the brightest seen since Hale-Bopp passed Earth in 1997.

James Coburn, the USU observatory manager, said comets are usually made of leftover pieces from the early solar system. 

“They could have been tossed out from the Oort Cloud by gravitational interactions with Jupiter,” Coburn said. “Finding out what’s in them is kind of like a time capsule.” 

The Oort Cloud is a massive shell around the solar system made from space debris and ice. Comets are sometimes referred to as “dirty snowballs” due to their icy and dusty composition. When the ice boils off, it becomes the comet’s telltale tail. 

“About 25 trillion miles away is how far it went out before it turned around again,” Coburn said. “Right now, it’s 46 million miles, so it’s roughly half the distance to the sun right now — it’s almost exactly that.” 

The tail of a comet will always point away from the sun, regardless of where the head is traveling. 

“The tail is formed by solar wind — charged particles — coming from the sun that pushes the gas away,” Coburn said. “The tail is leading right now.” 

Astronomers are constantly searching the skies for undiscovered comets.

“They’ll take pictures and compare picture to picture and watch for something that moves with respect to the background stars,” Coburn said. “We’ve had a year to study it and figure out its orbit.”  

Scientists can look at the spectra of a comet to discover what gasses it is composed of. Different elements give unique color spectrums when the light is separated into component wavelengths. An element’s wavelength is like a unique fingerprint — each one identifying only one element. This lets scientists understand what light-producing objects are made of without leaving Earth. 

Maria Rodriguez, assistant professor in USU’s physics department, said comets and asteroids have some important distinctions between them, one being how bright comets can get. 

“They rarely are so bright that you can see them with a naked eye,” Rodriguez said. “This one is very special because the materials that they’re made out of decompose faster, so we can see it.” 

According to Rodriguez, data from telescopes can be matched to simulations to understand what’s happening in space. 

“We have computer simulations now to see where and how often they would come close to the Earth. That is a very big chunk of the work that people do,” Rodriguez said. 

Quinton Harker, a first-year student studying engineering technology, was watching the comet from the Living Learning Center on Oct. 14. 

“How awesome is it to be part of an event that happens only once every 80,000 years?” Harker said. “I was born at just the right time, just the right place, to see this one comet.” 

According to Harker, people need astronomical events such as this to keep a broad perspective. 

“Without it, I feel like we would feel too much like the center of the universe, and everything would revolve around us, and we wouldn’t have any curiosity, and without curiosity, we can’t grow,” Harker said. “You should always be curious. You should never settle for an exact answer.” 

Harker said he enjoyed seeing the comet from USU’s campus but wished the viewing conditions could be improved. 

“I just wished we didn’t have as much light pollution,” Harker said. “If we could have a night a year where people just dedicate one night to turn off all the lights and just hang out outside, look up, and feel how insignificant we are in the grand scheme of time and the expanse of the universe.”