New Delhi: Since the Asteroid Terrestrial-impact Last Alert System (ATLAS) flagged the interstellar comet 3I/Atlas on 1 July 2025, the Earth has been moving away while the comet approaches the Sun. The comet is now on the other side of the Sun than the Earth, making it impossible to observe from the Sun. However, ESA is pointing its interplanetary missions with a better vantage point towards the interstellar visitor. Between 1 and 7 October, the operational Mars orbiters, Mars Express and the ExoMars Trace Orbiter will observe the comet during its close encounter with Mars. The comet will approach within 30 million km of Mars on 3 October.
The path of 3I/Atlas. (Image Credit: ESA).
Between 2 and 25 November, ESA’s Jupiter Icy Moons Explorer (Juice) spacecraft will observe the comets using a sophisticated suite of instruments designed to investigate the ice moons in orbit around the gas giant. Juice will be pointing towards 3I/Atlas soon after the closest approach of the comet to the Sun, which is likely to be in an active state because of the boiling away of the material making up the icy body. The halo around its nucleus is expected to reach its brightest extent, along with the longest extent of the tail stretching out behind it.
The third known interstellar object
3I/Atlas is the third known interstellar object to visit the Solar System after 1I/’Oumuamua in 2017 and 2I/Borisov in 2019. ‘Oumuamua was a flattened, rapidly tumbling asteroid, while both Borisov and Atlas are comets. 3I/Atlas poses no threat to the Earth, with the closest approach being about 1.8 Astronomical Units or AU, with a single AU being the Sun-Earth distance. The closet approach to the Sun will be at a distance of 1.4 AU, just inside the orbit of Mars, around 30 October. The comet is expected to reappear on the other side of the Sun by early December, allowing for a renewal of observations by Earth-based astronomical instruments.