In a year where we’ve already been treated to the “Great North American Solar Eclipse” in April and one of the biggest aurora displays in 500 years in May, what other amazing celestial attractions could 2024 have in store for us?
How about a bright comet with the naked eye?
Over the past few years, two comets have made headlines in the mainstream media. In early February 2023, comet C/2022 E3 (ZTF), informally called the “Big Green Comet,” flew close to Earth, then last month attracted the attention of comet 12P/Pons-Brooks because of its tendency to flare up suddenly. in brightness and appears to spew gaseous appendages resembling horns, giving rise to the nickname “Devil’s Comet”.
The only problem, as far as the person on the street was concerned, was that both comets were hard to see unless you were under a dark, unpolluted sky. And even through good binoculars or small binoculars, they were both rather indistinct and looked like nothing more than faint, blurry blobs of light.
Related: Space Photo of the Week: NASA sees ‘Platypus’ moving on Jupiter’s moon Europa
Clear? Easy to see?
The only problem, as far as the person on the street was concerned, was that both comets were hard to see unless you were under a dark, unpolluted sky. And even through good binoculars or small binoculars, they were both rather indistinct and looked like nothing more than faint, blurry blobs of light.
But by the end of this summer, we may have a good idea of ​​whether we’ll have a bright and easily visible comet gracing our early evening sky with the naked eye. The comet in question is C/2023 A3 (Tsuchinshan–ATLAS), discovered by the Asteroid Terrestrial-Impact Last Alert System (ATLAS) in South Africa on February 22, 2023. ATLAS is a robotic early warning system developed specifically for near-field detection. -Earth asteroids weeks to days before they could hit Earth.
Originally thought to be an asteroid, it was later discovered that the same object had been photographed six weeks earlier by the Purple Mountain Observatory (Tsuchinshan) in eastern Nanjing, China. It has since been determined that it was indeed an incoming comet.
When the comet was first spotted, it was well beyond the orbit of Jupiter, about 680 million miles (1.09 billion km) from the Sun. But on September 27 of this year, Tsuchinshan-ATLAS will make its closest approach to the Sun, coming within 36 million miles (58 million km). This is also the average distance of the planet closest to the Sun, Mercury.
And a little more than two weeks later, on October 12, the comet will pass just 44 million miles (71 million km) from Earth.
These data suggest that the comet could brighten to second or perhaps even first magnitude and develop a remarkable tail that could provide an eye-catching sight in the western evening sky in mid-October 2024.
It could also be nonsense
Unfortunately, there’s one caveat: calculations show that Tsuchinshan–ATLAS has an orbital eccentricity of 1.0001081, meaning it’s the “first” to come directly from the Oort cloud, a spherical envelope of icy space debris that scientists theorize is far away beyond the outer limits of the solar system and is thought to contain billions or even trillions of comets.
Comets originating from the Oort Cloud have never come close to the Sun before, and their nuclei are covered in highly volatile materials that evaporate away from the Sun, creating short-lived increases in brightness. But as these comets get closer to the Sun, their brightening slows or even stops altogether.
Most – though not all – comets originating in the Oort cloud usually end up as monsters. Typically, as these comets cross the orbit of Mars, their steady brightening trend begins to wane, much like a 20-mile marathon runner; “hitting a wall” so to speak. If the comet has emerged from the Oort Cloud, a sudden decrease in brightness may signal that it will eventually end up underpowered.
Not until mid-summer
Comet Tsuchinshan–ATLAS will not reach this point in its orbit until late July. If it continues to brighten even after this time, there is a good chance that it will develop into an eye-catching sight. But it’s more likely that if the brightening trend suddenly slows or even stops, all bets are off for a good show. Until then, all we can do is wait and watch.
Unfortunately, here in the Northern Hemisphere, we will not be able to check the status of Comet Tsuchinshan–ATLAS this summer, as it will be located too far south to be accessible by telescopes. However, those living in more distant locations such as Australia, New Zealand and South America will be able to watch it in the morning sky before sunrise.
We will have to rely on reports from these parts of the globe to tell us if the comet is on track to become a bright object.
Dusty reflections are the key to a good show
Another thing that could work in our favor is that the comet’s geometry relative to the Sun and Earth places it almost between the Sun and Earth around October 8, creating a phenomenon known as “forward scattering of sunlight.” If the comet is particularly dusty, dust particles ejected from the comet’s nucleus would preferentially scatter sunlight in the forward direction and could cause a dramatic increase in the comet’s brightness.
To this end, there are two comets to which Tsuchinshan–ATLAS could be compared that suddenly brightened due to forward scattering. The first was Comet Skjellerup–Maristany (C/1927 X1), which briefly became very bright in December 1927. Forward light scattering on December 18, 1927 made the comet visible in daylight due to blocking sunlight. by hand; since then it ranks among the largest comets of all time.
The second comet was Comet McNaught, also known as the Great Comet of 2007 and given the designation C/2006 P1, and was the brightest comet in over 40 years; easily visible with the naked eye to observers in the Southern Hemisphere in January and February 2007. The brightest comet on 12 January 2007 appeared at least twice as bright as Venus and, like Skjellerup-Maristany, was visible around the world on a wide scale. daylight next to the sun. This extreme brightness was also due to forward scattering.
Some calculations suggest that Tsuchinshan–ATLAS could become as bright as Venus around October 8, 2024 – although it will also be very close to the Sun in the sky, like the 1927 and 2007 comets. However, in the coming days, Tsuchinshan–ATLAS should quickly move north and become a good spot to observe in the western sky by mid-October. Although it will now be fading as it moves away from both the Sun and Earth, it will hopefully be bright enough to be easily visible to the naked eye, perhaps accompanied by a remarkable tail as well.
No guarantees
But there are no guarantees. There have been comets in the past that seemed to promise a big show that failed to live up to expectations. Comet Kohoutek from 1973-74 is a good example. On the contrary, there were comets that didn’t seem to perform well and ended up unexpectedly becoming celestial gems. Comet NEOWISE surprised everyone during the summer of 2020 by putting on a good show.
Legendary comet expert Dr. Perhaps Fred Whipple said it best when he said:
“If you must bet, bet on the horse, not the comet!”
In the meantime, keep your fingers crossed for Comet Tsuchinshan–ATLAS! Stay tuned to Space.com for future updates.
Originally published on Space.com.