On January 3 this year, Senior research specialist Greg Leonard at Mt. Lemmon Observatory discovered a faint speck. The 19th magnitude speck was an incoming comet, now called A1 Leonard (or simply comet Leonard). This comet will pass the closest to the Sun, its perihelion, on January 3, 2022, exactly a year after its discovery. But before that, comet Leonard is all set to decorate the skies of the Northern Hemisphere and will be visible with naked eyes. So if you missed comet NEOWISE last year, here’s your chance to see the ‘comet of the year!’
We have a visitor!
At the time of its discovery, Comet Leonard was about 5 Astronomical units (750 million km) from the Earth. That’s approximately the distance between the Sun and Jupiter. Calculations suggest the comet had roughly an 80,000-year orbital period. Hence, it has spent the last 40,000 years inbound from approximately 3700 AU (550 billion km). Comet Leonard crossed the orbit of Neptune in 2009 and is now heading towards its closest approach to the Earth (perigee) on December 12. It will pass within 0.233 AU (34.9 million km) of our planet. After its perihelion next year, the comet will continue its hyperbolic trajectory and exit the solar system, never to be seen again.
As comet Leonard whizzes past the Earth, there’s a good chance it will be seen with naked eyes. So here’s everything you need to know to see this distant visitor.
How to see comet Leonard?
Before jumping onto the dates to see the comet, I want to briefly introduce an important concept that will help you understand the procedure to see the comet. In astronomy, the brightness of a celestial object is denoted by a number called apparent magnitude—the lower the number, the brighter the object. The brightest object in the sky, the Sun, has an apparent magnitude of -26.7. The Full Moon’s apparent magnitude is -12.2. Unaided eyes can see up to a magnitude of +6.0
When the comet was discovered, its apparent magnitude was +19, way beyond the range of naked eyes. As the comet came closer to the Earth by November end, its magnitude came down to +8, still invisible without a telescope.
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However, Comet Leonard will brighten up in the first week of December. It will be first visible to the viewers in the Northern Hemisphere. Here are some of the important dates and positions of the comet.
December 6: The best day to see comet Leonard
Comet Leonard’s apparent magnitude will fall below +6 in the first week of December. It is currently predicted to peak at +4. December 6 is one of the best days to see the comet because of its proximity to the fourth brightest star in the night sky, Arcturus.
All you have to do is wake up early in the morning — about 90 minutes before the sunrise — and look east. First, try to locate Arcturus in the Bootes constellation. An easy way is to look for Ursa Major and extend its arc of stars, as shown above. The first bright star you spot along the extended arc is Arcturus (Remember the ‘arc to Arcturus’). Look to the left of this star, and you will have an excellent chance to see comet Leonard.
The reason why December 6 is a perfect date is because of its vicinity to Arcturus. Even those who don’t know much about the night sky can have a ‘reference point’ to locate the comet. If you have any difficulty in locating Arcturus, you can try one of these space apps.
December 12: A1 Leonard at perigee
The comet is moving at an impressive speed of ~254,000 km/hr. It’s so fast that it will change its position every day with respect to the background stars. As the month progresses, comet Leonard will travel closer to the horizon, and each day, it will become trickier to spot it. Finally, on December 12, A1 Leonard will pass the celestial equator Southward and pass 0.233 AU from the Earth — its closest approach to our planet. By now, the comet will be close to the Sun, as seen from the Earth, and won’t be easily visible.
December 13: A1 Leonard flips to an evening object
December 12 will be the last day when comet Leonard can be seen in the morning sky. After that, it will switch to an evening object, lying at the western horizon at dusk. Around this time, the comet will top out at a magnitude of +4. Observers in the Southern Hemisphere now have a chance to spot the fading comet in the coming days.
December 17: Hello, Venus!
On December 17, about 30 minutes after sunset, A1 Leonard will be located below planet Venus. You will need access to very clear horizons to see comet Leonard near Venus. The following day, the comet will pass just 0.028 AU (4.2 million km) from Venus, probably creating a Venusian meteor shower.
As A1 Leonard sinks below the horizon, it will pose with the kings of the evening sky — Jupiter, Saturn, and Venus.
January 3, 2022: A1 Leonard at perihelion
Exactly a year after its discovery, comet Leonard will reach its closest point to the Sun. It will come interior to Venus’ orbit and then continue its hyperbolic trajectory and escape the solar system, never to return. By Christmas, the comet will be beyond the apparent magnitude of +6.
Some important points to note
Luckily, the Moon will be absent in the early hours of the first week of December when the comet is escalating to its peak brightness for viewers in the Northern Hemisphere. It should be noted that an asteroid or a comet’s ‘performance’ as it approaches the Sun is challenging to predict. There are chances that A1 Leonard will top out at an apparent magnitude of +1, way brighter than currently predicted. However, we’ll have to wait.
Although comet Leonard will be visible under perfectly dark skies with naked eyes, a small telescope or even a pair of binoculars would be advantageous.
You’ll have to sacrifice your cozy bed and go out in the chilly morning to see A1 Leonard! But I am sure it will be worth it. I wish you clear skies and wide eyes.
Before you go, make sure you also read
- What did Voyager 1, Earth’s farthest spacecraft, see in its journey?
- Why the speed of light is what it is?
- The amazing science behind James Webb’s golden mirrors
Admin and Founder of ‘The Secrets Of The Universe’ and former intern at Indian Institute of Astrophysics, Bangalore, I am a science student pursuing a Master’s in Physics from India. I love to study and write about Stellar Astrophysics, Relativity & Quantum Mechanics.