Comet Leonard: How to spot the brightest comet of 2021?

In December 2021, residents of the Northern Hemisphere will have a chance to see the newly discovered Comet Leonard. At first, it will be visible through binoculars or telescopes, and later even with the unaided eye. In this article, AIN.UA shares details of the comet. Also, read where and when to look for it in the night sky.

About the comet

Comet Leonard, or C/2021 A1, was discovered in January 2021. It was beyond the orbit of Mars and was barely visible through powerful telescopes as a dim spot. But its trajectory is through the inner solar system, and it will pass both Venus and Earth in December 2021. And then it will turn around the Sun in January 2022.

It is difficult to predict the behavior of comets in general. But according to preliminary estimates, Comet Leonard will be bright enough in December to be seen with binoculars and even with the unaided eye. In a telescope, the comet looks very beautiful — having a green-tinged coma and an extended dust tail. Here is a photo of it published by NASA, created by combining 62 images taken through a telescope.

Image: NASA

Orbital calculations revealed that Comet Leonard had spent the last 35,000 years wending its way sunward after reaching aphelion at the chilling distance of around 3,500 astronomical units (An AU is approximately 93 million miles (150 million km) or a distance between the Earth and the Sun).

When and how could you see it?

In December, Comet C/2021 A1 can be seen from Earth’s Northern Hemisphere. For this, you will need to find some bright stars and constellations. The comet moves very fast, so its position among the stars will be changing daily during early December 2021.

For example, to observe the comet in early December 2021, 90 minutes before sunrise, you need to find Arcturus, the brightest star in the northern constellation of Boötes:


To quickly find constellations, stars, and planets in the sky, you can use mobile apps: point your smartphone camera at the sky, and the app will identify all celestial objects. Here are some apps: Heavens Above, The Night Sky, Stellarium, etc.

A little later, in mid-December, the comet can be spotted after sunset. Here is a picture of its position at the time of December 14-16, 2021.


On December 18, 2021, about 30 minutes after sunset, comet Leonard will be [possibly] visible to the naked eye below planet Venus.

For more detailed maps of the comet passing through the night sky, visit the EarthSky website.