Published: 2021-12-03 18:05:00
Updated: 2021-12-07 11:40:26
Posted December 3, 2021 6:05 p.m. EST
Updated December 7, 2021 11:40 a.m. EST
This week will be the only chance to ever observe Comet Leonard — one of the brightest comets to pass by the planet Earth.
Comet C/2021 A1 (Leonard) was discovered in January by Astronomer Greg Leonard from the Mount Lemmon Observatory near Tucson, Arizona. When we first told you about this comet, there were hopes it might be visible in our skies by December. That week has arrived.
Recent observations have shown a short, but dense, dust tail should make spotting it a little easier. Binoculars and a dark site will help you see it. By mid-to-late this week, you might be able to make it out with the naked eye under particularly dark skies. The best time to see it will be in the early morning hours, around 5 a.m. You'll have around 90 minutes to catch it.
Picking the best day to catch a glimpse of this icy visitor is a balancing act.
Like all comets, including last year's Comet NEOWISE, Comet Leonard will be at its brightest when it is nearest the sun. Unfortunately that's also when they are most difficult to see, either lost in the sun's glare or too low or even below the horizon.
By Friday or Saturday (Dec. 10-11), it will be too close to the sun to be able to see.
The comet currently has an estimated brightness (apparent magnitude) of around 6. Lower numbers are brighter and each jump represents a lot more brightness on this logarithmic scale. This is expected to decrease to under 4.3 by next weekend, or about 5 times brighter.
The best time to look will be mid-to-late this week. As the comet draws closer to the horizon, even through the comet is expect to continue brightening, you are looking through much more atmosphere, so it will actually appear dimmer.
By Dec. 13, the comet will be lost in the sun's glow. About a week later, if it survives perihelion, the comet should be visible in the evening sky through the end of the year.
The same energy from the sun that creates a brilliant tail can cause a comet to break apart, something that could happen tomorrow, next week or not at all.
As astronomer David H. Levy says, “Comets are like cats: they have tails, and they do precisely what they want.”