The comet C/2023 A3 (Tsuchinshan-ATLAS) will reach today September 27, 2024 perihelionthat is, the point of its orbit closest to the Sun, at a distance of “suns” 58 million kmcomparable to that between the Sun and Mercury, preparing to potentially become one of the brightest comets of recent decades. The perihelion is undoubtedly the most delicate moment of the passage of a comet in the internal Solar System, especially for a comet like C/2023 A3 which is on its first visit near the Sun: this is because a comet is a relatively fragile icy body, and the solar radiation near the perihelion can be intense enough to break it up, thus taking away the possibility of admiring its spectacle in the sky when it passes close to our planet.
Fortunately, however, Tsuchinshan-ATLAS seems to enjoy good health even in these critical moments, so much so that so far no particular indications of its fragmentation have been found. Certain, the last word has not yet been said and anything can still happen, as recently happened to the Devil’s Comet, Comet Nishimura and the Neanderthal Comet. But at the moment it seems likely that C/2023 A3 could be worthy of its ambitious moniker “comet of the century” and reveal themselves next Great Comet – that is, a particularly bright and spectacular comet – after the McNaught in 2007 (in the southern hemisphere) and the Hale-Bopp in 1997.
There are several reasons why Tsuchinshan-ATLAS has so much potential: it is in fact a comet very dusty (therefore capable of producing abundant coma and a long tail), it will pass at a relatively small distance from Earth (71 million km The October 12) and on October 9th, just 3 days away from its maximum proximity to the Earth, it will be very close to the Earth-Sun line and for this reason its brightness could be amplified by the phenomenon of forward scattering: Simply put, when the comet is backlit by the Sun it can spread its light towards the Earth, increasing its brightness tens or even hundreds of times.
At the moment the comet is visible mainly in the southern hemisphere; in our hemisphere it can be observed in the last hours of the night before dawn. From the October 9th we will be able to observe it immersed in the twilight immediately after sunset, therefore with a sky that is not yet completely dark. In the following days the observation time will improve, but at the same time the effect of the forward scattering: in short, the conditions will never be exactly ideal, but the potential of the show is nevertheless enormous. According to forecasts, if the comet does not fragment, the best observation opportunities will be the day of closest proximity to the Earth, therefore the October 12when the comet could also be safely visible to the naked eye with a luminosity – according to the most optimistic forecasts – comparable to that of Venus, which is the brightest celestial body after the Sun and the Moon. In the following days the brightness of the comet will gradually decrease while the crescent Moon will increasingly “disturb” the observations until its full phase which will reach the October 17.
While we keep our fingers crossed waiting to see what will happen to the comet in the next few hours, we will be able to observe the comet thanks to the Italian project Virtual Telescopewhich has a live broadcast scheduled tomorrow 28 September at 6:00 at the link below:
