Comet C/2021 A1 (Leonard) has just made its closest approach to Earth and promises to be visible, perhaps even with the naked eye, from Brazil in the coming days. But it won’t be easy to see him.
It was discovered exactly one year before its closest approach to the Sun, on January 3, 2021, by Gregory Leonard, from the Monte Lemmon Observatory (Arizona/USA). Its trajectory suggests that comet Leonard was in an orbit with a period of about 80,000 years, and spent the last 40,000 traveling towards the interior of the Solar System, from a distance of 3,700 astronomical units, the equivalent of 550 billion kilometers. But, when circling the Sun, on the 3rd, the gravitational recoil of our star will be enough to place it on a hyperbolic trajectory, that is, without a return. He will depart for interstellar space, where he will become one of the countless objects that travel between the stars and, from time to time, cross a planetary system, as happened with the interstellar bums ‘Oumuamua and Borisov, the first stars of their kind to be detected by astronomers.
Before perihelion, it has already made its maximum approach to Earth, last Sunday (12). At the time, it was just under 35 million kilometers from us and its brightness bordered on magnitude 4, in the constellation of Ophiuchus. As the human vision is capable of seeing stars with a magnitude of up to 5.5 (the smaller the number, the brighter), in theory it is possible to look for them with the naked eye, but only in skies free from light pollution. With binoculars, it seems like a more assured proposition.
In the first days of December, it was only visible from the extreme north of Brazil, but the situation is already improving for observers in the southern hemisphere. On Thursday (16), it can already be seen from the Midwest regions, Southeast and South, in the constellation of Sagittarius, with more or less even brightness. Each day, with the departure, the star becomes more and more discreet, reaching the end of the month with a magnitude above 6, in the constellation of Pisces Austral.
In any case, comets have unpredictable behavior. Sometimes there is a sudden increase in activity, with a corresponding increase in brightness, so it’s worth keeping an eye out.
And how to find him? Simple. Look towards the west, just after the sun has dropped below the horizon. With each passing day, the comet will be higher in the sky shortly after dark (though it never really gets too far from the western horizon). On Friday (17), it will be the most favorable day to locate him, as he will be close to Venus, easily recognizable by his ultra-potent glow right after sunset. Use binoculars in the vicinity of the planet to find him.
In addition to the passage of comet Leonard, we are left with the traditional Gemini meteor shower, the result of our planet’s annual encounter with the debris trail left by the asteroid Phaethon (or Phaethon). The peak occurs in the early hours of this Tuesday (14), but unfortunately the almost full moon can overshadow the observation of less bright shooting stars. The best time to observe comes around 2 am, when the constellation Gemini, from which the meteors seem to emanate, presents itself towards the north.
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