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Witness Comet Leonard Now Through Christmas!

Comet Leonard Is Back!

By “Astro” Mark Laurin, Keystone Science School Adjunct Instructor & Volunteer


 Since Comet Leonard was discovered almost a year ago, and during that time, its orbit brought it closer and closer to the Earth and the Sun.  The closer it gets to the Sun, the longer its tail and coma grow in color and size.  Up until now, in order to see the comet, it required being a hearty soul, committed to achieving full consciousness before early dawn, and having the aid of magnifying optics as the comet couldn’t be seen with the unaided eye.   But now, Comet Leonard, a long period comet, having let 70,000 years pass since its last flyby of Earth, is now giving all the world an encore appearance at a more reasonable hour.  That’s right, for us here in the northern hemisphere, the show begins in the early evening in the southwestern sky.  For the next three days, if conditions stay true, you should be able to see Comet Leonard with your naked eye and wave “hello and goodbye” to our interplanetary traveler.

Finders Keepers

Comet C/2021 A1, Comet Leonard, was named after its discoverer, American astronomer Gregory J. Leonard.  Mr. Leonard is a researcher working at the Mount Lemmon Infrared Observatory, and he identified the comet near the planet Jupiter on January 3rd, 2021.  Comet Leonard is a dirty ice ball made up predominantly of methane, ammonia, and water gasses that has a few miles under its belt to make its holiday appearance.  About 35,000 years ago, it was on the opposite side of its elongated elliptical orbit, its farthest point away from the Sun.  This moment in any celestial object's orbit is called the aphelion.  At that point, Comet Leonard was around 325 billion miles away from the Sun.

How to Find Comet Leonard?

To find Comet Leonard this evening December 17th through the 19th couldn’t be easier.  About one hour after sunset (4:42pm MST), face southwest, and locate the planet Venus low in the southwestern horizon.  Venus is the brightest object in that part of the sky.  Next, look halfway between Venus and the horizon.  You’re looking for a dimmer diffused circular fuzzy object, similar to a star but not as crisp.  You might even see the tail if you have a pair of binoculars on hand.  The close conjunction between Comet Leonard and Venus occurs at 7:08 pm MDT which will make it easier for you to find the comet and it is also when the comet is closest to the planet Venus on its journey towards the Sun.  After the 19th, and up to Christmas, you'll need binoculars or a telescope to see it.  Following the 25th, the comet will fall low in the western sky making it very difficult to see in the northern hemisphere. 

In the end, on January 3rd, about 56 million miles from the Sun, Comet Leonard reaches its closest point to the Sun in its orbit, called the perihelion.  Comets usually brighten as they reach perihelion with occasional brightness outbursts, increasing the comet’s visibility.  Yet, comets are notoriously unpredictable.  Once Comet Leonard rounds the Sun it will be thrown out of our solar system into a slightly hyperbolic orbit, never to be seen again.  Yep, for us, it’s one and done.

A Holiday Gift - A Once in a Lifetime Experience.

During your life, the universe gives you many “once in a lifetime experiences” and Comet Leonard is one of them.  The last people on Earth to have witnessed this comet were our distant ancestors living on Earth 35,000 years ago.  And we’ll be the last Earthlings to see this comet ever again.  Think about that for a moment and embrace the opportunity.  Get inside the security of a warm coat, hat, and gloves and step outside.  Look up and let the magic of a holiday winter evening compel you to find Comet Leonard, and bear witness.  Consider it your gift from the Cosmos. 

 Wishing you and yours an astronomically delightful holiday season.