Media Release

Udupi, Oct 3: A cosmic visitor graces the festive seasons this year. A comet designated C/2023 A3—a rock that formed far from the Sun, primarily made of dust and ice—moved out of its place and headed toward the Sun tens of thousands of years ago. Discovered by the Purple Mountain Observatory in China and the ATLAS Observatory in South Africa, it is named the Tsuchinshan-ATLAS Comet. Astronomy enthusiasts can watch this comet in October.

The C/2023 indicates that this is a non-period comet discovered in 2023 and will not return. The A3 indicates it was the third comet discovered in the first half of January 2023, having been first observed on January 9, 2023.

Such non-periodic comets originate from the Oort Cloud, located at the outer edge of the Solar System. The Oort Cloud begins at 2,000 AU (1 AU equals to Earth-Sun distance: 150 million km) from the sun (2,000 x 150 million km) and extends to around 200,000 AU. It contains many icy rocks and dust, forming a shell-like region around the solar system. Comets like C/2023 A3 primarily originate from this region.

The comet moved out of Oort Cloud into an orbit around the sun, in a extremely eccentric elliptical-orbit (highly stretched circle with the sun away from the ‘center of the circle’). It was closest to the sun on September 27, with a distance of 58 million km (5.8 crore km) from the sun. That’s when it became visible to the naked eye. Now on its way back, it will be closest to earth on October 12, at a distance of 7,067,200 km, moving at a velocity of 80.5 km per second. This makes the comet suitable for observations on several days this month.

Currently, the comet can be spotted in the East between 5:00 and 5:45 am, moving closer to the horizon each day and disappearing on October 7. To find the comet, look East during this time and identify two bright stars: Regulus (Makha Nakshatra) from Leo Constellation (Simha Rashi) on the left and Alphard (Alpha Hydra) from the Hydra constellation on the right. Both stars are at an altitude of 25 degrees, which one can measure by extending the arm with little finger and thumb open. If the thumb touches the horizon, the little finger will point 25 degrees away. Once one spots the two stars, visualize an equilateral triangle formed with a third point near the horizon; the comet should be around this point. The comet is observed at a magnitude of 2.0 (the smaller the number, the brighter the object) and will be the brightest until October 7, making it visible to the naked eye during this time.

If the comet is missed to view in the morning skies, one can spot it between October 12 and 30, after sunset, just to the right of Venus in the west. The comet is best viewed through binoculars or small telescopes. Long exposure images will also reveal the comet and its tail during this time.