Huge, ancient and 'really pretty': Check out the NEOWISE comet now while you still can

An ancient and massive ball of ice is creating a dazzling light show in the night sky as it whizzes past our planet — and if you want to catch a glimpse of it, you had better hurry. 

The NEOWISE comet — or C/2020 F3, as it is officially known — will hit its closest proximity to Earth on Wednesday, before heading to the outer parts of our solar system and venturing out of sight for more than 6,000 years. 

"So this is a really good time to go spot it," University of Arizona astronomer Amy Mainzer told As It Happens guest host Duncan McCue. 

"There's not a whole lot of moonlight right now, so ... it keeps the sky darker. This is a kind of a fuzzy, streaky object that you'll see if you can get to a dark spot in the sky and take a look for it."

Mainzer is the principal investigator for NASA's Near Earth Objects Wide-field Infrared Survey Explorer (NEOWISE) mission, which uses an infrared telescope to spot comets that threaten to collide with Earth.

It was her team that first spotted the comet, hence its nickname. But there's no need to worry. NEOWISE is not on a collision course with our home planet.

Instead, it's passing by at a distance of 103 million kilometres, and it should make its closest approach to Earth at about 9 p.m. ET Wednesday. 

It is expected to be visible in the weeks afterwards, but will dim and eventually vanish from sight as it continues along its massive orbit.  

To see it on Wednesday night, you'll need to find a spot without too much light pollution and look northwest toward the horizon and near the Big Dipper, Mainzer explained. 

"So that little scoop, it looks like a ladle, right? With a handle and a scoop. So you're going to look below the scoop in the Big Dipper towards the northwestern sky," she said. 

Fire and ice 

Comets are collections of ice and rock that generate gaseous tails as they pass near the sun. That's why something so cold and dull appears so bright and sparkly.

"If you think about it, this is a frozen mixture of ices and rocks that has been out way in the deep freeze of deep space for thousands and thousands of years. And now it's getting as close to the sun as the planet Mercury," Mainzer said.

NEOWISE passed closest to the sun on July 3, she said, "and that has just put this huge blast of heat on it, just like getting broiled in an oven."

"So you can imagine that all the ices and rocks and everything are just getting blasted off the surface of this comet," she said. 

"And that's why we see it as being so spectacular and bright right now."

Many comets don't survive the process, she said. But with a diameter of five kilometres, NEOWISE has more than enough surface to withstand the heat for a little while.

"It's a pretty good sized comet," she said. 

As old as the solar system 

Not only is the comet massive and frigid — it's also very, very old. It was formed near the birth of our solar system 4.6 billion years ago, according to NASA. 

"[Comets] represent the conditions in our solar system for when it was first formed," Mainzer said.

"Our Earth, of course, has lots of weather and geology on it that keeps the surface more fresh. So for us to get to look at these really old time capsules is special because it lets us tell a little bit about where we came from."

This marks a rare opportunity to see a comet with the naked eye, she said. The last time that was possible was when Hale-Bopp passed the Earth in 1997.

"Most of the time when we see them with our space telescope, we're seeing them, as, you know, dots on a monitor, on a computer," Mainzer said.

"But this one, I have to admit, it's really weird. I mean, I know it's real and I know it's there, but it is a really, really spectacular treat to be able to see it with my own two eyes."

In fact, she says she can't seem to take her eyes off it.

"I can't help it," she said. "I just keep wanting to go look at it. It's really pretty."

Written by Sheena Goodyear. Interview produced by Katie Geleff.