Farewell, Halloween Comet: C/2024 S1 Has Disintegrated!
Comet C/2024 S1 was supposed to light up the sky this Halloween, but sadly it has just died in the heat of the Sun. Its last fragments are still burning away, but they won't be putting on any kind of show for us. Here's a look at what happened and why the loss of C/2024 S1 is such a big deal.
Contents
- Quick facts about Comet C/2024 S1 (ATLAS)
- Comet C/2024 S1 (ATLAS): what happened?
- Comet in October 2024
- More facts about Comet C/2024 S1 (ATLAS)
- Comet type – the Kreutz sungrazer family
- Comet C/2024 S1 (ATLAS) disintegration
- How to find the next comet in the sky: the comet tracker apps
- C/2024 S1 (ATLAS) Conclusion: too bright to survive
Quick facts about Comet C/2024 S1 (ATLAS)
- Official name: C/2024 S1 (ATLAS)
- Former name: A11bP7I
- Type: non-periodic Kreutz sungrazer comet
- Closest approach to Earth: October 23
- Brightness at the closest approach: mag 8.7
- Perihelion: October 28
- Predicted brightness at perihelion: mag -2.6
- Visibility: disintegrated
Comet C/2024 S1 (ATLAS): what happened?
On October 28, Comet C/2024 S1 (ATLAS) was on its way to perihelion, its closest point to the Sun, where temperatures soar to around 1000°C. By then, the icy materials in the comet’s nucleus had fully vaporized, and even its more durable refractory materials were severely heated. As the comet began to "fall" into the Sun, it simply evaporated.
In fact, C/2024 S1 lasted longer than many expected! The first signs of disintegration were observed on October 9, followed by a dangerous outburst on October 18. Yet the comet still made it into the view of the Solar and Heliospheric Observatory (SOHO). We also tracked the comet's path until the very last moment, and it was more than exciting!
Comet in October 2024
October 16-23: approaching Earth
The comet is visible with small backyard telescopes late at night in the Southern Hemisphere. C/2024 S1 reaches the elongation from 35 degrees to 20 degrees from the Sun in the sky.
Key dates:
- October 20: enters the constellation Corvus
- October 22: passes the star Gienah (mag 2.6)
- October 23: reaches a magnitude of 8.7 at its closest point to Earth (0.88 AU), and passes the star Algorab (mag 2.9)
October 24-28: approaching perihelion
As the comet approached the Sun, its brightness increased, but it was too close to the Sun for direct observation. Observers tracked it live with the SOHO instruments. As C/2024 S1 was about to reach perihelion, it completely disintegrated due to the heat of the Sun.
Key dates:
- October 25: enters the constellation Virgo, where the Sun is also located
- October 26: passes the star Spica (mag 1.0)
- October 28: disintegrated during the perihelion passage, with a peak brightness of -2.6.
More facts about Comet C/2024 S1 (ATLAS)
C/2024 S1 (ATLAS) discovery
Comet C/2024 S1 (ATLAS) was discovered on September 27, 2024, by the ATLAS survey in Hawaii. It was given the temporary designation A11bP7I while awaiting official confirmation. On October 1, it has been confirmed and officially named C/2024 S1 (ATLAS).
C/2024 S1 (ATLAS) name
The name of the comet contains data about where and when the comet was first seen:
- The letter C indicates a non-periodic comet – comets of this type originate from the Oort cloud and may pass through the Solar System only once or take from 200 to thousands of years to orbit the Sun;
- 2024 S1 means the comet was discovered in 2024, in the second half of September (this corresponds to the letter S in the IAU comet naming system), and was the first such object discovered in this period;
- ATLAS means the discovery was made using the Asteroid Terrestrial-impact Last Alert System (ATLAS) telescope.
Comet type – the Kreutz sungrazer family
This comet is thought to belong to the Kreutz sungrazer family, a group of comets that pass very close to the Sun. The comets of this type are thought to be fragments of one large comet that broke up several centuries ago. Historically, Kreutz sungrazers, such as Ikeya-Seki (1965) and Lovejoy (2011), have often become particularly bright, visible even in daylight.
Comet C/2024 S1 (ATLAS) disintegration
Comet C/2024 S1 (ATLAS) disintegrated during its perihelion passage on October 28. Here are the stages of the comet's evolution that foreshadowed its breakup.
October 9: fragmentation of Comet C/2024 S1 (ATLAS) nucleus first reported
As far back as October 9, 2024, an ongoing breakup of the comet's nucleus was reported. The researchers say that the intense release of gas, along with tidal or rotational forces, may have caused fragmentation. The fragmentation, in turn, may have led to the release of lots of dust and gas, which is why we saw the comet brighten rapidly after it was discovered.
October 18: one more sudden brightening
On October 18, the comet suddenly brightened again, which indicated that its nucleus was still breaking apart. However, part of the comet’s nucleus survived and continued its journey.
October 26-28: C/2024 S1 (ATLAS) in SOHO images
Though it was uncertain if C/2024 S1 would reach SOHO’s field of view, the comet did appear in images from the C3 LASCO instrument on October 26. It showed up as a small but strikingly bright object — more luminous than most SOHO-observed sungrazers.
On October 28, the comet entered the C2 SOHO LASCO view. Observers could watch in real-time as the comet evaporated near its closest point to the Sun. Unfortunately, C/2024 S1 didn’t survive its perihelion passage, meaning it won’t grace our skies after perihelion.
The Kreutz sungrazers have historically been some of the most spectacular comets. Check out our fun quiz to learn more about famous Great Comets from history!.
How to find the next comet in the sky: the comet tracker apps
It’s a shame that C/2024 S1 (ATLAS) didn’t make it to naked-eye visibility, but don’t worry! There’s another promising comet on the way! C/2024 G3 (ATLAS) is expected to reach its peak brightness on January 13, 2025. Start tracking it now with the Sky Tonight or Star Walk 2 apps:
- Type C/2024 G3 into the search bar.
- In Sky Tonight, tap the target button next to the comet's name. The app will show you the comet's location on the sky map.
- In Star Walk 2, simply tap the comet's name. The app will show you the comet's location on the sky map.
- For real-time tracking, point your device at the sky and follow the white arrow.
C/2024 S1 (ATLAS) Conclusion: too bright to survive
Comet C/2024 S1 (ATLAS) evaporated as it neared perihelion on October 28. But no need to be downhearted! Check out our upcoming comets schedule, and use Sky Tonight or Star Walk 2 to track them in your sky!
