There’s good news for anybody who enjoys stargazing: An astronomer recently discovered a new comet, now known as Comet Leonard. What makes the news even more exciting is that, although the comet is still a long way from Earth, it should be bright enough to see with the unaided eye this December -- and then, it won’t ever pass us again.
What Exactly Are Comets?
About the “size of a small town,” a comet essentially is an iceball made of frozen gasses with embedded rock and dust particles, NASA explains. Comets, at least for a time, orbit the sun.
As a comet nears the sun, it warms up and its ice begins to change from a solid to gas. This produces what’s known as a “coma,” which is the fuzzy-shaped cloud surrounding the ball of ice. The coma, by the way, can be thousands of miles in diameter, according to Live Science.
What’s even cooler is that radiation pressure -- or solar wind -- then “blows” the expanding coma out to form the tail that comets are known for, Space.com explains.
Comet Leonard, cataloged C/2021 A1 by NASA, was discovered by -- and named in honor of -- astronomer Gregory J. Leonard on January 3, 2021. Leonard is a senior research specialist for the Lunar and Planetary Laboratory’s Catalina Sky Survey, located at the Mount Lemmon Infrared Observatory, just outside Tucson, Arizona.
Now, for the science behind the discovery: When Leonard first found the comet’s image, it was faint, with a magnitude of 19. That means the comet is nearly 160,000 times dimmer than the stars you can barely see at night with the unassisted eye, Space.com explains.
One astronomical unit (AU) is equal to the Earth’s average distance from the sun -- 92.9 million miles. When Comet Leonard was first detected, it was approximately five AU from the sun, which places it near Jupiter’s orbit. The reason Comet Leonard appeared so dim was that it was just beginning to warm up and develop its coma.
When You Can See Leonard
The good news is that there is plenty of time for scientists to observe Comet Leonard -- and watch it get increasingly brighter. That’s because it won’t reach perihelion -- the point when it’s closest to the sun -- until January 3, 2022.
The NASA Jet Propulsion Laboratory estimates that Comet Leonard will come closest to Earth on December 12, 2021, at around 14:13 UTC. At that time, Comet Leonard will be approximately 21.7 million miles from Earth. You can translate UTC to your local time here.
Although it’s too soon to say for sure, NASA scientists expect that from December 14 to 16, people in the U.S. will be able to see Comet Leonard just after sunset. Although the comet should be visible to the unaided eye by looking low in the southwest horizon, it will be easier to see using binoculars.
It’s important to note that if you do plan to track the comet’s progress using a telescope, it will take some patience. It’s true that Comet Leonard will be traveling at approximately 158,076 miles per hour, or 44 miles per second. However, due to the great distances of space, the comet will appear to be moving through the sky slowly, EarthSky explains.
If you are using a telescope, you’ll need to fix Comet Leonard’s position in relation to background stars, and then look away. Then, in five to 10 minutes, look through the telescope again. You should be able to see that the comet has moved across the sky, EarthSky explains.
Once In A Lifetime
Comet Leonard has a hyperbolic orbit. That means it will move through the inner solar system once and then continue moving further out into space. In other words, this truly is a once-in-a-lifetime event because after next January, it will never be possible to see Comet Leonard from Earth again.
Editor’s Note: Head here for more stargazing events in 2021.