The passage of a comet is a rare event, even more so when it can be observed with the naked eye. Discovered in February 2023, comet Tsuchinshan-Atlas is currently crossing our inner solar system, surveying an invisible route that should bring it as close to the Sun as possible over the weekend, offering a spectacle visible with simple binoculars, or even the naked eye.
This small, rocky, icy body, whose exact size is not yet known, has a long-period orbit. The last time it passed close to our star was around 80,000 years ago, according to astronomers’ calculations. History does not say whether the Neanderthals who populated the European continent at that time witnessed its last visit.
Where to look in the night sky?
C/2023 A3, from its scientific name, is expected to reach its maximum brightness this Friday, September 27, when it reaches its perihelion, the closest point to the Sun. As comets approach our star, the ice in their nuclei sublimes, releasing a long trail of dust reflecting the Sun’s light.
It’s this brilliant hair that we can observe from Earth. In our latitudes, it should be possible to catch a glimpse of it in the sky in the hour before sunrise and for four mornings in a row, until Monday September 30. The hairy star will appear a few degrees above the east-southeast horizon.
Our tips for not missing a thing!
The mornings of September 29 and 30 will offer the best conditions for observing it, as the Moon’s glow will be less intense. The comet’s brightness remains a mystery, although some astronomers predict that it could be as bright as the 20 brightest stars in the night sky.
Once you’ve spotted it in the sky, be sure to stow your phone in your pocket, to let your eyes adjust to the darkness of the night sky and ensure they can absorb as much of the light emitted by the comet as possible. It may be a good idea to bring along binoculars for better observation of the comet.
While the passage of comet Tsuchinshan-Atlas can be observed on the outskirts of major cities, the ideal is to go to an area sheltered from light pollution with a clear horizon. To date, France has five dark sky reserves, a list of which can be found by clicking here (new window).
After September 30, the hairy star will be lost in the Sun’s glare, before reappearing in the night sky near the western horizon around October 12. On that day, comet Tsuchinshan-Atlas will be at its closest point to Earth, just 70 million kilometers from us, and it may once again be possible to observe it, one very last time!
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