Most comets are the most difficult to see against the sun's glare or hidden below the horizon.
Leonard is a comet, alas, no exception. It should be visible in small telescopes and binoculars in the Northern Hemisphere's pre-dawn sky as it increases in brightness for part of December, and later in the month just after sunset.
The comet that Gregory J. Leonard discovered is located in the Santa Catalina Mountains, 17 miles northeast of Tucson, Arizona.
The sky in December is what you can see.
The comet has been very dim since it was discovered. Most comets are too faint for amateur telescopes to catch, but for a short time in December, they should rise out of the ordinary.
The icy ball is making a pre- Christmas appearance to us. About 35,000 years ago, the comet was at the end of its elliptical path and 3,500 units from the sun. The Earth's average distance from the sun is 149,565,894 kilometers.
35 thousand years ago, comet Leonard resided some 325 billion miles from the sun, in an environment that was almost unimaginably cold, the temperature at which all motion stops. The conglomeration of icy gases like methane, ammonia and water vapor is reacting to the increasing warmth of the sun as it nears the home stretch of what is likely to be its last visit to the sun.
Leonard's month is December.
The image of the comet Leonard and the meteorite was captured by Steven Bellavia. Steven Bellavia is the image credit.
As Leonard approaches the Earth, his brightness should increase. During the early days of December, when the sun is setting, observers should focus on the eastern sky, halfway up from the horizon to the point directly overhead. The constellation Canes Venatici has two stars, the 3rd-magnitude star Cor Caroli and the 3rd-magnitude star Muphrid.
You should run across a fuzzy, 6th-magnitude glow. That will be a comet.
The second week of December is when the best compromise between increasing brightness and decreasing altitude can be found. The sky will be free of light after the new moon.
The eastern sky can be seen on the morning of December 6. Arcturus is a brilliant orange-yellow star in the constellation of Botes the Herdsman. If you use binoculars, you can see a comet in the sky about 5 degrees to the left of Arcturus. The comet's dust tail should be pointing straight up.
The comet's magnitude is expected to be +5.5, bright enough to be seen without any optical aid in a dark sky. The comet will be approaching us at a rate of 1.5 million miles per day, so it will be brighter, but it will also be lower in the eastern sky.
The International Space Station is home to a comet that stunned skywatchers in 2020. The image is from NASA/Bill Ingalls.
By the morning of December 12th, Leonard will have a magnitude of +4.3, but will be only 10 degrees above the eastern horizon. The length of your fist is roughly 10 degrees. The comet will make its closest approach to Earth at 10:54 a.m., according to NASA. The time is 1354 GMT.
On that day, the morning's visibility will end, but comet Leonard will come back for several appearances in the evening sky. On December 17th, it will be sliding below Venus. It's low to the southwest horizon about an hour after sunset, if you look with binoculars.
Visibility might be improved by forward scatter.
Skywatchers are hoping that the comet will perform better than expected due to a phenomenon known as "forward scatter." The comet's nucleus scatters light toward the observer, making it appear brighter.
The comet might get up to 2 magnitudes brighter than current predictions suggest, because it will be at a very favorable phase angle during the middle part of December. The comets that have benefited from forward scattering are Skjellerup-Maristany in 1927, West in 1976, Bradfield in 1980 and McNaught in 2007. The comets became much brighter than expected.
Not all comets like forward-scattering. Will Leonard benefit? We can only watch and see what happens.
The comet will reach its closest point to the sun on January 3 at a distance of 57.2 million miles. It will be thrown out of the solar system into a hyperbolic circle once it rounds the sun.
Space.com's readers would like to see pictures of the night sky, so send your photos, comments, and your name and location to spacephotos@space.com.
Joe is an instructor and lecturer at New York's Hayden Planetarium. He writes about astronomy in publications. Follow us on social media.
