Comet C/2023 A3, known as Tsuchinshan-ATLAS, became visible from late September to mid-October 2024, with peak brightness in early October shortly after sunset. It was observed from both the northern and southern hemispheres before fading from view by October 24. The comet stood out for its brightness, size, and extremely long 80,000-year orbit, last passing the inner solar system when Neanderthals lived on Earth.
Discovery of comet C/2023 A3
The comet was discovered on January 9, 2023, by China’s Purple Mountain Observatory (also called Tsuchinshan) and the Asteroid Terrestrial-impact Last Alert System (ATLAS) in South Africa. Tsuchinshan has a long history in astronomy, while ATLAS is a modern automated system for detecting near-Earth objects.
What makes Comet Tsuchinshan-ATLAS unique?
- It has an orbital period of about 80,000 years.
- Its nucleus size and composition contributed to exceptional brightness, at times rivaling Venus and Sirius.
- It was discovered independently by two observatories, giving it a dual name.
Orbital path
C/2023 A3 follows a vast elliptical path that takes it far into the outer solar system before returning close to the Sun and planets. Its last visit to the inner solar system was tens of thousands of years ago.
Physical characteristics
The comet’s nucleus contains ice, dust, and rock from the early solar system. The head of the comet is about 130,000 miles wide, and its tail can stretch up to 18 million miles. As it nears the Sun, heat turns its ice into gas and dust, creating a bright coma and tail pushed outward by the solar wind.
Technical aspects of comet Tsuchinshan-ATLAS
Viewing times and locations
The comet reached its closest point to the Sun (perihelion) on September 27, 2024, and its closest point to Earth on October 12, 2024, at a distance of about 44 million miles. Observers in the northern hemisphere enjoyed the best views as it appeared higher in the sky.
How to photograph Tsuchinshan-ATLAS
Photographing the comet requires a camera with manual settings, a tripod, and a remote shutter or timer to avoid camera shake. Longer exposures capture its motion and detail, and binoculars or a telescope improve clarity.
Previous comet sightings
Bright comets like Halley and Hale-Bopp have been recorded throughout history. Today, astronomers use ground-based telescopes and space probes to monitor comets, studying their chemical makeup and behavior in detail.