'Christmas comet' to zip through sky, won't be back for 80,000 years

By Brian Lada,
Comet Leonard seen with the help of a telescope on November 28. Photo courtesy of University of Hertfordshire Observatory

The 2020 holiday season featured a "Christmas star" when Jupiter and Saturn appeared extremely close and shined together, and this year, stargazers are in for another gift as the brightest comet of 2021 races through the evening sky.

Comet C/2021 A1, more commonly referred to as comet Leonard, was discovered earlier this year and made its closest approach to the Earth on Sunday. Before its approach, it was visible only in the early morning sky, but its journey has now made it more prominent in the evening sky, making it a target for backyard stargazers.


The "Christmas comet" will appear in the evening sky throughout the rest of the year, but folks should look for it sooner rather than later as it will become dimmer and dimmer heading into the final days of December.

Comet Leonard is not expected to be a repeat of comet NEOWISE, which impressed stargazers last year on its journey through the inner solar system.

"Based on how bright comet Leonard has been appearing recently, it looks like it will not be as bright as last year's comet NEOWISE," said Gordon Johnston, a program executive at NASA headquarters.


"This comet should be visible with a backyard telescope or binoculars and may be visible to the naked eye under very clear and dark observing conditions," Johnston said.

Even with the help of a telescope or binoculars, it will look like a fuzzy green star with a small tail.

The green track shows where Comet Leonard will appear in the sky through Dec. 25, 2021. Image courtesy of NASA

Friday will be a good opportunity to spot the comet as it will appear directly below Venus after sunset.

The fuzzy green comet will continue to glow below and to the left of Venus through the weekend before eventually shifting directly to the left of Venus by Christmas.

"Viewers will need a clear view of the horizon, as the comet will only be a few degrees above the horizon as evening twilight ends," Johnston said.

The coming nights will be the only chance to see comet Leonard as it will not swing past the Earth again for another 80,000 years.

After comet Leonard fades into the depths of the solar system, it is difficult to say for sure when another comet will emerge from the darkness and become bright enough to see with the naked eye.


The University of Hawai'i discovered comet C/2021 O3 (PANSTARRS) earlier this year and predicts that it could be bright enough to see without the help of a telescope or binoculars in late April or early May of 2022, but it is difficult to say for certain.

"Comets are notoriously difficult to predict in terms of brightness and visibility," NASA explained. "With comets, you really never know."

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