The comet C/2024 G3 ATLAS will reach the perihelion (the point of its orbit closest to the Sun) the January 13, 2025 after well 160,000 years since the last time. This long-period comet, discovered on April 5 this year and originating in the cold and remote outskirts of the Solar System, is one of the so-called comets sunskirtera term that refers to those objects that pass within 33 solar radii of the center of the Sun (about 23 million km, less than half the distance between the Sun and Mercury). C/2024 G3 will in fact transit at only 13.5 million km from the solar surface, three times closer than Mercury is to the Sun.
Predictions indicate that it could become one of, if not the, comets brightest comet of 2025with a luminosity similar to that of Venus (the brightest celestial body in our sky after the Sun and the Moon). However, this show will only be reserved for observatories of the southern hemisphere. The comet is currently located in the constellation of Scorpius, shining with a magnitude of 8 not visible to the naked eye. Its orbital configuration unfortunately makes it a comet that is difficult to observe from the medium and high latitudes of the Northern Hemisphere. The only time you can attempt observation from Italy it’s ai early January when the comet will rise about forty minutes before the Sun. Even on this occasion, however, it will be difficult to observe with the naked eye seen the morning glow.
When comet C/2024 G3 ATLAS will pass: visibility forecasts
The comet currently has a magnitude equal to 8above the threshold of visibility with the naked eye, however it becomes increasingly brighter with each passing day due to its approach to the point of minimum distance from the Sun. The comet, having already passed into the inner Solar System 160,000 years ago, should survive to the close encounter with the Sun January 13, 2025when it will pass to approx 13.5 million km from the solar surface.
The latest projections predict that the comet will reach a magnitude equal to –4.5similar to that of Venus, although this value, since comets are extended objects, refers to the brightness of the entire object. This high value will also be achieved thanks to the effect of forward scattering (forward scattering), a phenomenon, which also occurred for comet C/2023 A3 (Tsuchinshan–ATLAS), which occurs when the comet, being between the Earth and the Sun, artificially increases its brightness thanks to dispersion of sunlight in the direction of the observer caused by the dust and ice crystals surrounding the comet. C/2024 G3 is likely to become the brightest comet of 2025a year in which no more comets are expected to become bright enough to be visible to the naked eye.
At perihelion on January 13, theelongation of the comet, i.e. the angular distance from the Sun, will be about 5°too close to be observed with amateur instruments. However, the probe SOHO from NASA, which continuously monitors the Sun, should allow us to observe the comet near perihelion and immediately understand whether it will have survived the close encounter.
Where will the comet be seen in the sky and when will it be possible to observe it
These days the comet it is not visible from Italysince it is only twenty degrees away from the Sun and at the same height above the horizon at dawn, therefore rising in conjunction with the Sun itself. Furthermore, it sets about 2-3 hours before the Sun. The situation will improve slightly early January when the comet it will rise around 7 in the morningabout 40 minutes before the Sun. However, given its angular proximity, it will hardly be possible to see it in the morning glow in the southeast, at least if you are equipped with excellent observing instruments.
At perihelion, the comet is angularly at suns 5th from the Sun so impossible to observe. Moving away from the perihelion, although the angular distance from the Sun increases, the visibility of the object from Italy will not improvesince the orbital configuration of the comet will make it more easily observable at sunset for those located in thesouthern hemisphere. Although its solar elongation is the same for both hemispheres, the small angle that the comet forms with respect to the south-eastern horizon when seen from north of the equator keeps it hidden in the twilight.
THE early January I am therefore there‘only occasion to observe the comet from Italy, while from perihelion onwards the best visibility will be from the southern hemisphere. Residents of this hemisphere should be able to observe the comet’s long tail starting January 16. From that moment the solar elongation will increase rapidly from 12 to 18 degrees, with the comet moving from the constellation of Capricorn to that of southern Pisces. By the end of January it may still be a naked-eye object of magnitude 5, with a faint tail visible in binoculars.
Where does comet C/2024 G3 come from?
Comet C/2024 G3 was discovered on April 5, 2024 from the system Asteroid Terrestrial-impact Last Alert System (ATLAS) when it was a very weak object of magnitude 19 at 4.4 astronomical units from Earth. Preliminary data on its orbit indicated that it could be a comet on its first pass through the inner Solar System, coming from Oort clouda remote region of the outer Solar System that contains the remnants of the Solar System’s formation and serves as a reservoir of comets.
As the months passed, the comet was observed several more times, allowing astronomers to refine the calculations on the comet’s orbit. It turns out that C/2024 G3 is actually one dynamically old cometthat is, it has already passed through the internal Solar System other times, thus managing to survive the close encounter with the Sun. C/2024 G3 is a long-period cometwhose last passage in our area dates back to well 160,000 years agowhen our ancestors had recently started using clothing.
