7:15 AM | *Another celestial event for sky viewers...Comet Leonard should become visible in December*
Paul Dorian
This image of Comet Leonard was taken on November 10th from the desert Southwest. Courtesy EarthSky.org, Brian Ottum (Instagram)
Overview
In the wake of the partial lunar eclipse that was enjoyed by many, there is growing hope for another celestial event in December that too can be a worthy celestial event for sky viewers. The brightest comet of the year is heading our way and it should become visible in December as it makes its closest approach to Earth. On December 12th, 2021, the comet will be just 35 million kilometers away and it could be visible in the early morning sky. After that, the comet will transition into the evening sky and it will reach perihelion, its closest point to the sun, around January 3rd, 2022.
The blue curve traces the predicted brightness of Comet Leonard. Crosses are recent observations. Credit: Comet Observation Database, spaceweather.com
Details
Astronomer Greg Leonard discovered the comet that now bears his name in early January of this year while viewing the skies at the Mount Lemmon Observatory in Arizona. During the next month, Comet Leonard’s brightness is expected to increase sharply, perhaps more than 100 fold. Most forecasts expect the comet to reach magnitude +4 which is an easy target for small backyard telescopes and perhaps it’ll be even visible to the naked eye in dark areas by the second week of December. As the comet approaches the sun in early January, 2022, forward scattering of sunlight through the comet’s dusty atmosphere could create an additional surge in brightness according to spaceweather.com. Comets are typically brightest around the time they’re closest to the sun.
Location of Comet C/2021 A1 (Leonard) on December 10, 2021. By then, it will be brighter, but closer to the horizon, as seen from the U.S. about 30 minutes before sunrise. Illustration by Eddie Irizarry, using Stellarium. Courtesy EarthSky.
An amazing feature of Comet Leonard is that it’s an ultrafast comet according to EarthSky.org. It’s traveling at 158,084 miles per hour (254,412 km/h or 70.67 km per second) relative to Earth. Despite its incredible speed through the vast space of our solar system, don’t expect to see this comet swoosh across the sky. Like planets, comets do move in front of the star background, but only very slowly due to the large distances involved. Observers using telescopes will have to take a close look at the comet’s position relative to background stars. Then compare the view five or 10 minutes later to detect its motion, because its great distance will cause it to appear as a very slow moving object.
Location of Comet C/2021 A1 (Leonard) on December 15, 2021, about 30 minutes after sunset, facing southwest as seen from the U.S. Illustration by Eddie Irizarry using Stellarium. Courtesy EarthSky.
Meteorologist Paul Dorian