How UAE stargazers can spot comet that appears 'once every several thousand years'

Time will tell, but it could be the 'brightest of the century', according to a Dubai-based expert

Poojaraj Maniyeri

Published: Mon 30 Sep 2024, 12:31 PM

Last updated: Sun 6 Oct 2024, 4:04 PM

Stargazers in UAE are up for a treat in October, with the opportunity to spot a comet that appears once every several thousand years. Named C/2023 A3, this long-period comet was discovered by the astronomical survey system that also contributed to the discovery of Earth's new 'mini moon.'

The comet could be the "brightest of the century, if it brightens to more than 0.5 magnitude," said Khadijah Ahmad, operations manager at Dubai Astronomy Group. [In astronomy, the brighter the object, the lower the number assigned as magnitude.] However, she added, this cannot be predicted just yet. While the comet was initially bright, it can behave in unexpected ways as it approaches the Sun.

Advertising

Stay up to date with the latest news. Follow KT on WhatsApp Channels.

When can UAE residents spot it?

UAE residents have two opportunities to try and spot this celestial phenomenon.

Its first appearance in UAE skies was just before sunrise on September 27 in the east, where it can still be spotted till October 2. However, sighting it with the human eye during this initial appearance will not be possible.

Khadijah told Khaleej Times that, after this, "it will reappear from October 12 to October 30 in the evening, after its perihelion (closest approach to the Sun), and be visible in the western sky shortly after sunset."

During this period in October, the celestial object will likely be visible with the naked eye, but "it is best observed with a telescope for the clearest sighting", she added. Visibility can be impacted by the comet's reaction to the sun, the clarity of the weather, and the distance from the horizon.

Here is an image, captured in Wadi Shawka, Ras Al Khaimah, on September 28 at 5am, by Dubai Astronomy Group. The photo was a single shot with exposure of 15 seconds:

Here is a clearer, processed photo of the comet:

C/2023 A3 is low on the horizon, which means light will be scattered by the Earth's atmosphere, which may make it harder to observe the comet.

To spot the comet, observers can look to the horizon (eastern or western depending on the dates) in areas with minimal light pollution. Locations away from city lights, like deserts, would be ideal, Khadijah noted.

At 11am on October 6, the comet was captured by Mohammed Odeh using one of the telescopes of the observatory located in the Al Khatim Desert in Abu Dhabi. The telescope has a diameter of 102 mm and a focal length of 714 mm. A 685 nm red filter was used, and 189 frames were stacked to obtain the final image.

What is the Oort cloud?

Long-period comets, such as C/2023 A3, can have orbits that bring them into the inner solar system only once in thousands or millions of years, and they usually originate from the Oort cloud, Khadijah noted.

The Oort cloud was first proposed in the 1950s by astronomer Jan Oort who theorised that "certain comets come from a vast, extremely distant spherical shell of icy bodies surrounding the solar system," according to Nasa.

This cloud is the most distant region in our solar system. While sunlight takes a little over 8 minutes to reach Earth, it would take around 10 to 29 days to reach the inner edge of the Oort cloud. And to pass through its outer edge? It would take nearly a year and a half.

According to Nasa, most known long-period comets have been seen only once in recorded history because of their long orbital periods. Our species did not exist the last time that some comets passed through the inner solar system, while others have never ventured close to the Sun since formation, it said.

ALSO READ: