The Leonids are here and 2020 is a good year to observe them

The Leonids are here and 2020 is a good year to observe them

Its maximum activity will take place on the night of Tuesday 17 to Wednesday 18. To enjoy the sky we just need the atmosphere to be propitious keeping the skies clear

The Leonids are here and 2020 is a good year to observe them

From the moonless nights of this weekend we can already begin to observe the Leonids, the meteor shower created by the comet Tempel-Tuttle. Its maximum activity will take place on the night of Tuesday 17 to Wednesday 18.

During the new moon

The Leonids are visible from the 6th to the 30th of November, approximately. But its maximum activity takes place around the 17th, at which time up to 15 meteors per hour can be observed. As the name suggests, the Leonids have their radiant (the point in the sky from which all the meteors seem to come) in the constellation Leo.

The new moon takes place on Sunday 15, so the two or three nights before and after will offer us very dark skies. On the night of the Leonid maximum, Tuesday, November 17, the Moon will be a crescent edge that will lie down in the west a couple of hours after sunset. The constellation of Leo will rise in the east at about 1 am in the morning.

The Leonids are here and 2020 is a good year to observe them

So it will be preferable to observe the meteors from that time on and in the east, when the moonless night has become very dark. For the observation of the Leonids, it is enough to stand in a dark place, protected from light pollution, and not limit oneself to the constellation of Leo, but to monitor as much of the celestial vault as possible because, although they seem to come from that constellation, the meteors they can appear anywhere.

A comet that visits us every 33 years

The Leonids are originated by the comet Tempel-Tuttle, a 33-year-old comet that has a nucleus of about 2 kilometers in size. They are very bright and extremely fast meteors that can reach speeds of about 250,000 kilometers per hour. However, that of the Leonids is a rain that varies greatly from year to year. It is particularly active in the years when the Tempel-Tuttle passes close to the Sun (at perihelion). Therefore, the 33-year period of the comet is reflected in a 33-year period in the activity of this meteor shower.

A couple of years before and after the perihelion of this comet, the Leonids already present a large number of meteors and can become the most spectacular meteor shower among all those that take place throughout the year.

The Leonids are here and 2020 is a good year to observe them

During the last years, the Leonids have not presented a great activity and it is not expected very high for this. We will have to wait for the next step of the Tempel-Tuttle perihelion, in the year 2031, to see a great show.

1833, the golden year of the Leonids

Ever since Aristotle explained that meteors were bubbles of gas that exploded in the atmosphere, that is, for more than 2,000 years, meteor showers had been considered atmospheric phenomena. However, the observation of the Leonids in 1833 would revolutionize the study of meteors.

The American astronomer Denison Olmsted was sleeping on the night of November 13, 1833, when the annual Leonid peak occurred. It seems that about 72,000 meteors were observed per hour (about 20 per second!) And Olmsted almost missed the show. Fortunately, his neighbors woke him up and made him go outside. He then observed the Leonids in great detail and was completely intrigued by their origin. In a newspaper article that he published in the New Haven Daily Herald , he asked other scientists and citizens in general for information to help him find the true cause of the phenomenon. It was a prime example of what we now call 'citizen science'.

Thus Olmsted realized that all the poking seemed to come from the same point in Leo (the radiant) and, after studying his behavior and his history, he concluded that it was an astronomical phenomenon. Every astronomy lover will enjoy Olmsted's wonderful description of the phenomenon in an article in The American Journal of Sciences and Arts that can be read here. In that same magazine are other articles on the meteor shower, written by other observers than had been previously requested by Olmsted himself. The illustrations from the period are also impressive. It really must have been a great show.

And the planets

If the Leonids are not favorable to us this year, we can always take the opportunity to observe the planets that are splendid on these autumn nights. The thin arc of the crescent moon will appear very close to Jupiter and Saturn on the nights of November 18 and 19. Venus and Mercury can be seen before sunrise. Mars, which continues to shed its reddish glow for most of the night, will be in conjunction with the gibbous Moon on the night of November 25-26.

As we approach the winter solstice, the nights are lengthening a couple of minutes each day, and we already have almost 14 hours of night skies. To enjoy the sky we just need the atmosphere to be propitious by keeping the skies clear.

Rafael Bachiller is director of the National Astronomical Observatory (National Geographic Institute) and academic of the Royal Academy of Doctors of Spain.

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