A burst of activity increased the luminosity of Comet Leonard

Update December 20, 2021

Numerous astronomers enthusiasts around the world have reported that a startle activity has earned the comet Leonard a sudden sudden of his brightness these last few hours. Her magnitude would have continued to climb until the third (or even second), according to testimonies. On December 20, in the early evening, the star diffuse was more easily visible to theeye naked (see the article below for his position today in the sky at dusk).

This increase in its activity is in line with its approach to Sun (perihelion January 3). Its core of ice and dust weakens under the effect of warmer temperatures and solar wind. Hopefully it doesn’t break in the next few days.

After passing in the vicinity of the Earth – 35 million kilometers anyway – on December 12, comet Leonard (C / 2021 A1) was closest to Venus on Friday, December 17. It grazed it some 4.2 million kilometers, which was the closest visit in history known to human memory from a comet to our dear neighbor! If we were on Venus, and her sky was clear, there is no doubt that the spectacle would have amazed us.

Anyway, seen from the Earth, it is also very beautiful: we can see the approximation of the comet with the one that many Earthlings nickname the ” Evening Star After sunset. However, you have to wait for the blazing twilight lights to fade a bit to have a chance to spot the brightest comet of the year. It is these days at the peak of its luminosity (seen from the Earth), around magnitude +4. Theoretically visible to the naked eye, thestar very diffuse will be revealed to you even more easily, and nicely, through a pair of binoculars, and of course, a telescope or a telescope if you have one.

Where is comet Leonard?

To find it, it is not very difficult, it passes below the brightest star in the sky – after the Moon and the sun –, Venus of course (magnitude -4.6).

Tonight, December 17, C / 2021 A1 (Leonard) will be above the southwest, low on the horizon (look for a clear spot to observe it).

On December 18, Comet Leonard will still be near Venus, but to its left, or east (see figure above) of the sparkling star. The comet should still be visible.

On December 19, C / 2021 A1 (Leonard) continues to take off, overtaking Venus in the sky. Still in Sagittarius, she will soon enter the small constellation from Microscope. Skimming the terrestrial horizon more and more, its visibility becomes difficult.

Very swift, the comet continues to darken for the next two weeks towards the Sun until January 3, 2022, date of perihelion, the point of orbit closest to our Star. It is exactly one year after its discovery by Gregory Leonard. It will then have become very difficult to observe it. As for seeing her again, everything indicates that it will never be possible again, because she will be ejected from our Solar system.

Comet Leonard will be visible in the evening and these will be the last times we can see it

Article by Xavier Demeersman published on December 15, 2021

Comet Leonard: remember its name because it will be talked about in December and until the beginning of the year 2022. Discovered a year ago, it promises to be the comet of the year! Here is how, when and where to observe it?

C / 2021 A1 (Leonard), or to put it more simply, Comet Leonard, looks very promising for visibility with the naked eye in the coming days. Came from edge of the solar system, the star is now visiting the vicinity of the neighboring and (almost) twin planets, the Earth and Venus.

Its smallest distance with our Planet was this Sunday, December 12 at 1:52 p.m. UT precisely, i.e. 2:52 p.m. Paris time, it was then some 35 million kilometers, which remains very far away, and therefore without any risk for us. , Terrans. A few days later, on December 17-18, it will be the turn of Venus to welcome it in its neighborhood, and this time to touch it since it will only pass four million kilometers from its surface! We dare not imagine the spectacle that will be visible from there.

Then, the comet will continue on its way to perihelion, the point of its orbit closest to the Sun, which it will reach on January 3, 2022, exactly one year after its discovery by the astronomer Gregory J. Leonard – who has him naturally given its name – to the Mount Lemmon Observatory. C / 2021 A1 will then pass 92 million kilometers from our Star (i.e. 60% of the distance between the Earth and the Sun), which is a lot, and therefore reduces the risk of it disintegrating. Although it is not excluded that this will happen; this naturally depends on the cohesion of its core of ice and dust. The risk of it breaking up is always great for a comet when it passes through the hottest region of the Solar System. Hopefully this will not happen, so that one can make the most of the spectacle of his visit to the sky in the morning and then in the evening. Because this will be the last time it will pass through here: researchers believe that, by its high speed, it will be ejected from our Solar System in a few thousand years. “This is the last time we will see her” assures Gregory Leonard (researcher at Lunar and Planetary Laboratory from the University of Arizona), which remember also in passing how unpredictable comets are: “A wise and famous comet discoverer once said: ‘comets are like cats, they both have tails and both do exactly what they want”! “.

Where is comet Leonard?

Specialists predict that Comet Leonard could remain below the magnitude 6 bar (limit below which a star is visible to the naked eye) for several days, and perhaps flirt with magnitude 4, thanks to its passage as close as possible to the Earth. Everything indicates that its brightness will peak between December 11 and 13 (seen from Earth, always). However, is it clearly visible in the sky? The answer is yes under certain conditions because it will soon disappear from the morning sky to emerge in the evening one. As the star is diffuse – not punctual like a star or a planet – it is not easy to distinguish it with the naked eye. To do this, it is necessary to know your position well and to redouble your attention. To maximize the chances of admiring it, it is strongly recommended that you bring a pair of binoculars or an instrument collecting more than light (telescope or refracting telescope), if you have one (or know someone who has). You will then be able to appreciate the beauty of its core surrounded by gas, its hair and its long tail that stretches out into interplanetary space, opposite the Sun.

For weeks now, the comet has been followed by many amateur astronomers around the world who share on the social networks photos of their hunts. Among the most beautiful and spectacular are those where C / 2021 A1 is displayed in front of galaxies, located in the background, tens of millions oflight years of the earth. More recently, on December 3, Comet Leonard came close to theglobular cluster Messier 3 (M3). Apparently of course, because M3 is actually over 35,000 light years away from us, and the comet.

Comet Leonard is visible at dusk

At the beginning of December, comet Leonard is visible high in the sky in the second part of the night until thedawn, passing Dogs de Chasse au Bouvier, to the south-east. Its high velocity (254,000 km / h) makes it traverse the celestial vault with great strides compared to the “fixed” stars (which appear fixed to us). Over the nights, the star will lose height in the sky and approach the horizon as it advances towards the Earth. On December 9, she entered the constellation Serpentarius and will soon disappear from the morning sky (before dawn on December 13), to slide into the evening sky on December 14. It will then be in front of the Milky Way. But you will have to look for it in the twilight lights, very low above the southwest horizon.

On December 16, in the evening, we can admire it in front of Sagittarius. On December 17 and 18, in the vicinity of the sparkling Venus. The opportunity to remember that these beautiful eveningswinter will be enhanced by the alignment of our neighbor with Saturn and Jupiter. And to this are added the Geminids, the most beautiful rain ofshooting Stars of the year whose peak of activity coincides with the night of the comet’s smallest distance from Earth.

We therefore cannot recommend enough that you go out and enjoy these beautiful celestial shows in the heart of the longest nights of the year. By turning the back, as always, at the light pollution, in order to admire all those objects that fill the darkness. Comet Leonard will undoubtedly be Comet of the Year if its brightness continues to increase as advertised, so if you miss it you will have to wait 35,000 years to see it again (estimates from its orbital period).