As we are learning nowadays, hope should be tempered by facts that change daily.

So when writing about Comet ATLAS, here are the possibilities: It may be the next great comet, a naked-eye dazzler, something to cheer us in late April and May when we could use a thrill.

Or it may be kind of dim. A faint little fuzzball. A dud.

That won’t stop people from trying to see it.

“I tried to observe it last week,” said Bill Cloutier of New Milford, one of the directors of the John J. McCarthy Observatory in New Milford. “But anyone who hypes a comet may be in for a disappointment. They tend to be very unpredictable.”

“It is very difficult to say,” said Bob King, an astronomer and writer whose AstroBob blog can be found atastrobob.areavoice.com and who has written about ATLAS for Sky & Telescope Magazine. “I think the high estimates — as bright as the moon — are way off.”

But, King said, even if it underperforms people should be able to see ATLAS with a pair of binoculars in the northwest sky — a nice comet, if not a great one.

“It could be pretty good,” he said.

ATLAS stands for the Asteroid Terrestrial-impact Last Alert System, a NASA-funded asteroid warning system centered at the University of Hawaii. Its staff spotted the comet in December, 2019. It’s full name is ATLAS (C/2019-Y4.)

At first, it seemed another faint object in the sky. But it the last few months, it brightened so dramatically that it got people thinking ATLAS could be special.

A great comet is one that people can see in the night sky without telescope or binoculars. They are ghostly and wonderful.

Anyone who was around for Comet Hyakutake in 1996 or Comet Hale-Bopp in 1997 will remember the thrill of looking up in the night sky and getting the gift, freely given, of just seeing them.

“You could see it from a city,” Diana Hannikainen, observing editor for Sky & Telescope, said of Hyakutake.

“People are amazed when I show them pictures of those comets,” said Cloutier. “It’s amazing that people didn’t see them.”

What gives people hope for ATLAS is that it is following the same orbit as the Great Comet of 1844. ATLAS and the 1844 comet may be part of a larger object that broke apart many millennia ago.

Astronomers have calculated that its hyperbolic orbit takes it past our solar system and around the sun every 4,800 to 5,000 years or so. Which means that the last humans to see it, if they saw it, were Bronze Age people. The next time it comes around will be in the 7000s.

Heidi Hammel, a planetary astronomer who is vice president for science at AURA — The Association of Universities for Research in Astronomy — said ATLAS comes from the vast region lying between the Kuiper Belt, where Pluto dwells, and the Oort Cloud, the far, far distant region ringing our solar system, filled with trillions of objects.

At its most distant, ATLAS swings out 57 billion miles from the sun.

“It sounds like a lot, but it’s not,” Hammel said.

Comets — along with being beautiful — contain elements that give astronomers new insights about the origins and formation of the solar system.

Some comets circle through our solar system regularly, Hammel said, and have shed a lot of their material. But a visitor from so far away is a little more interesting.

“It’s a little more pristine,” Hammel said.

As comets approach the sun, they melt, leaving behind a trail of dust and debris that we see as the comet’s tail. These can be spectacular — Hyakutake’s spread far behind it, while Hale-Bopp had two tails.

But sometimes, as comets approach the sun, they fragment. That’s what happened in 2013 to Comet ISON — another great comet hope that tattered.

There’s a fear that could happen to Comet ATLAS. At its closest to the sun, on May 31, it will be only 23.5 million miles away — closer than the planet Mercury. It could fall apart as well.

Or, having freshened so quickly, it may get brighter than it is now.

Right now, it’s near the Big Dipper in the north sky — you may be able to see it with binoculars. By May it will move closer to the northwest horizon.

And if it gets brighter still? If becomes, well, great?

“It’s a different story,” Hammel said.

Connecticut Media Group