Science / Leonard, the brightest comet of the year, to fly past Earth on December 12

Zoom News : Dec 08, 2021, 11:38 AM
New York: On November 24 this year, telescopes picked up a bright comet in northern predawn skies between two galaxies. The bright trail of light travelling across the galaxy was Comet C/2021 A1, also known as Leonard, announcing its arrival in the skies over Earth.

The arrival comes nearly a year after it was first discovered around Jupiter in January 2021.

Telescopes picked up the comet sporting a greenish coma harpooning the heart of NGC 4631 also known as the Whale Galaxy. Its closest approach to Earth (and even closer approach to Venus) still to come, comet Leonard will grow brighter as December goes by.

The comet will have its closest approach to Earth on December 12, just a couple of weeks before it reaches its closest distance from the Sun. While comets are notoriously hard to predict, some estimations have Comet Leonard brightening to become visible to the unaided eye in December.


The Comet was first discovered by astronomer Gregory J Leonard in January this year at the Mount Lemmon Observatory. A senior research specialist, he spotted the faint object, which was nearly 1,60,000 times dimmer than the faintest stars visible to the unaided eye. At the time, the comet was 149.565 million kilometres from the Sun near the orbit of Jupiter.

According to, the initial calculations showed it was travelling in an exceedingly long, flattened elliptical orbit taking it out as far as 523 billion kilometres. And as it came closer to the Sun, it began going directly from a frozen state into a gas leaving behind a trail.

Astronomers suggest that the reason behind its brightness could be its orbit itself, which demonstrates that it is not a "new" comet coming directly from the Oort cloud. Instead, it is travelling in a closed orbit and probably visited the vicinity of the sun at least once before, about 70,000 years ago.

Since the object has been far away from solar rays for so long it could have frozen carbon dioxide, nitrogen, and carbon monoxide, which vapourise giving it a high brightness. But, as they come closer to the Sun its brightness will begin diminishing. Meanwhile, its close approach will also play a part in its high bright visibility.


The comet will be visible a couple of hours before sunrise, low in the east-northeast sky through the constellations Coma Berenices, Boötes and Serpens Caput. It will be easy to spot using a small telescope or a pair of binoculars. It will pass between Arcturus and the handle of the Big Dipper as it approaches the horizon right around the time of its closest approach to Earth.