Photo: Wellington Carvalho
Very curious little celestial bodies, made of ice and dust, that come from the edge of the solar system and literally fall towards the sun. This is the definition of comets given by math professor and amateur astronomer, member of the Edmond Halley (Caeh) Astronomy Club of Marialva, Maico Zorzan.
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When they survive, comets are responsible for spectacles in the sky. And for astronomy lovers, the good news is that this show can be seen soon. The reason is that comet Leonard, discovered in January of this year, is already visible at dawn, through binoculars, and expectations about it are high. “Because it’s still intact, because of its orbit and the magnitude it’s reaching at the moment”, justifies Maico.
To form the spectacle, the ice and dust boulder approaches the sun and literally starts to melt from the heat. This process gives rise to two tails, one of water vapor and dust and the other of ionized gases, which cause a very beautiful effect and draw attention. “The more the comet melts, the bigger the tails are, which is exactly what attracts the observation”, he says.
If comet Leonard survives, it will be possible to see the spectacle in the sky in the second half of December, in the early evening, after the sun has dropped to the horizon.
For Maringá, the expectation is a beautiful spectacle, which can be seen best in the northwest region of the city, always after sunset. “It will be visible for at least a week. But the duration will depend on its magnitude”, he says.
Comet Leonard is currently at a magnitude close to 7. The magnitude is the apparent brightness of the celestial body relative to the observer. The smaller the magnitude, the brighter, the larger the less bright. “Our eye catches well up to a magnitude of 7. Above that we already have difficulty. The Moon, for example, is at – 3. At magnitude 7 it would be at the threshold of the human eye. If you get to 5 it will be very visible. But the smaller the magnitude, the brighter and more interesting it gets, and that’s what we’re hoping to happen, because depending on the magnitude we only need our eye. We’ve already had comets with a brightness below 2”, reports Maico Zorzan.
But, the astronomer suggests caution, since comets are very unpredictable bodies and, when they get closer to the sun, “anything can happen”, he says. They can destroy themselves before reaching the sun’s perihelion or after passing through it, surviving the sun’s maximum approach but being drawn into it and flinging themselves into it. A comet can also collide with meteors, meteoroids or suffer gravitational action from the sun, Jupiter and other planets. “When it approaches the sun and splits its core, nothing happens, which is what has happened in recent years with countless comets”, he explains.
Time to observe
A common mistake people make is to think that the comet ‘scrapes’ the sky, like what happens with meteors. However, according to Maico Zorzan, it is present for a period of time, orbiting the sky, just like the sun and moon. “Despite being a theoretically fast orbiting body, it follows the sun, which allows it to be observed for hours, for several days.”
How is a comet discovered?
The research process for the discovery of comets consists of capturing several photos of the same region of the sky, for several days. A software analyzes if any object is moving, and this movement is checked if it is a comet, asteroid or other celestial body.
Amateur astronomer Maico Zorzan says that in Brazil there is the Sonear Observatory, in MG, commanded by Cristovão Jacques, whose curriculum includes the discovery of some comets, asteroids, including comet Jacques, Sonear, among others. “We also have Leonardo Amaral, who discovered comet C/2020 O2 Amaral from his backyard in the interior of São Paulo last year. We have a lot of people doing science well done in Brazil”, he reports.
The names are given according to the time and year of discovery and pay homage to the discoverer or observatory who discovered it. The new comet, for example, was discovered by Gregory J. Leonard, of the Mount Lemmon Observatory, located in the state of Arizona, United States. “That’s why his name is C/2021 A1 Leonard,” says Maico Zorzan.
The return of the famous Halley Comet
As they are wandering celestial bodies, it is not possible to predict the discovery of a comet, nor when they will be visible after this discovery. “It is not possible to have an exact prediction of how this celestial body will be observed over the years. It is necessary to constantly evaluate, it is astronomy being carried out moment by moment”, explains Zorzan.
However, some comets can pass close to the Sun more than once. This is the case of the famous Halley comet, which passed in the sky for the first time in 1986 and already has a date for the next show: 2061. This is because, according to Maico Zorzan, it it has a well-defined orbit, and has been known for a long time. “We have even calculated your tickets from the ancient age. It was for many the comet that brought the fascination for astronomy”, he says.
History
The last spectacle of a comet took place between June and July of last year, the comet Neowise, which could be seen with the naked eye in the Northern Hemisphere. In the southern hemisphere, the most recent show was in 2011, between Christmas and New Year, when comet Lovejoy, discovered by an Australian amateur astronomer named Terry Lovejoy, survived.
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