How to see 'Christmas Comet' Leonard before it disappears forever

Use Venus, currently a brightly visible presence in the southwestern sky around sunset, as a way to help you find the comet.

ByKatie Hunt and Ashley Strickland, CNN, CNNWire
Wednesday, December 22, 2021
How to see 'Christmas Comet' in sky tonight
Comet Leonard was discovered in 2021 and made its closest approach to Earth on Dec. 12, according to AccuWeather.

Comet Leonard, which last passed by Earth 80,000 years ago, has been dazzling the night sky before Christmas, and there's only a few days left to see the celestial object before it disappears forever.

The imager onboard the Solar Orbiter, a joint mission between NASA and the European Space Agency, captured Leonard streaking across the sky with the Milky Way in the background in a stunning animated sequence of images from Friday to Sunday. Venus and Mercury are also visible in the top right of the animation, with Venus appearing brighter and moving from left to right.

Stargazers on Earth have also been chasing the comet, a mass of space dust, rock and ice about a half-mile (1 kilometer) wide.

Comet Leonard made it closest approach to Earth on December 12, coming within 21 million miles (34 million kilometers) of our planet. The comet will be visible in the skies of both the Northern and Southern hemispheres until the end of this month.

It travels closest to the sun on January 3, taking it within 56 million miles (90 million kilometers) of our star, slightly more than half Earth's distance. If it doesn't disintegrate, its trajectory will fling it into interstellar space, never to return, said NASA.

NASA also captured an image of the comet with its Solar Terrestrial Relations Observatory-A spacecraft.

Ultrafast comet appears from Earth to crawl

The comet was discovered in January by astronomer Greg Leonard, a senior research specialist at the University of Arizona Lunar and Planetary Laboratory. He began tracking the fuzzy bit of light on January 3.

"The fact that the tail showed up in those images was remarkable, considering that the comet was about 465 million miles out (from Earth) at that point, about the same distance as Jupiter (from Earth)," he said this month.

It's also an ultrafast comet, blazing through the inner solar system at 158,084 miles per hour (71 kilometers per second), but it will still appear like a slow-moving object due to its distance from Earth, according to EarthSky.

Use Venus, currently a brightly visible presence in the southwestern sky around sunset, as a way to help you find the comet.

Beginning December 13, "this comet will appear very low above the horizon just after sunset," said Leonard. "It will skim across the west-southwestern horizon between now up until around Christmastime. The fact that it's so close to the horizon makes this comet a bit challenging to observe."

Most comets with long orbital periods, like Comet Leonard, come from the Oort Cloud, a large, icy area that surrounds our solar system. It's too far away from Earth to have ever been visited by a spacecraft.

"When the tug-of-war is won by the gravity of our solar system, an object may start moving inwards, accelerating as it gets closer to the sun," Leonard said.

As comets near the sun, these giant iceballs begin to shed some of their material, which forms a halo, or coma, around the object. Dust and gas stream behind comets to form their extremely long tails. Most comets only become visible to us as they travel through the inner solar system, where Earth is located, during their long orbits of the sun.

Understanding comets can open a window into the formation of our sun and solar system because they act like cosmic time capsules of material.

"As much as we have great science on comets, they're still highly unpredictable with respect to their size, shape, chemical makeup and behavior," Leonard said. "A wise and famous comet discoverer once said: 'Comets are like cats -- both have tails, and both do precisely what they want.'"

Ancient human ancestors may have witnessed Comet Leonard during its last pass by Earth about 80,000 years ago. But it won't be coming around again.

"This is the last time we are going to see the comet," Leonard said. "It's speeding along at escape velocity, 44 miles per second. After its slingshot around the sun, it will be ejected from our solar system, and it may stumble into another star system millions of years from now."

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Video provided by AccuWeather.