Comets
Comets are cosmic snowballs of frozen gases, rock, and dust that orbit the Sun. When frozen, they are the size of a small town. When a comet's orbit brings it close to the Sun, it heats up and spews dust and gases into a giant glowing head larger than most planets. The dust and gases form a tail that stretches away from the Sun for millions of miles. There are likely billions of comets orbiting our Sun in the Kuiper Belt and even more distant Oort Cloud.
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ALPO Comet News for March 2025
3/3/2025
The last months of 2024 and the first month of 2025 saw a flurry of bright comet activity. Unfortunately, the middle months of 2025 are expected to experience a bright comet drought with no comets expected to become brighter than 10th magnitude until late in the year.
Currently, the best comets are outbursting 29P/Schwassmann-Wachmann in the evening sky at 10-11th magnitude, departing C/2023 A3 (Tsuchinshan-ATLAS) in the morning sky, also at 10-11th magnitude, and the diffuse remains of C/2024 G3 (ATLAS) for southern hemisphere observers.
The next reasonably bright comet may be newly announced C/2025 A6 (Lemmon), which will be a northern hemisphere-only object, peaking at 9th magnitude or perhaps a few magnitudes brighter in October and November.
The monthly ALPO Comet News PDF can be found here. All are encouraged to join the discussion over at Cloudy Nights at https://www.cloudynights.com/topic/956463-alpo-comet-news-for-march-2025//

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Meteors Shed Light on Comet Composition
8/22/2024

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In a study recently published in Icarus, researchers using visual and video observations of 47 young meteor showers have found differences in the sizes of meteoroids produced by short-period and long-period comets. The difference in meteoroid sizes may be a relic of the conditions in the early solar system when these objects formed. Jupiter-family comets usually crumble into smaller, denser meteoroids, whereas long-period (Oort Cloud) comets often crumble into sizes indicative of gentle accretion conditions.

 


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Comet's impact triggered downfall of ancient Hopewell?
2/1/2022

The rapid decline of the Hopewell culture about 1,500 years ago might be explained by falling debris from a near-Earth comet that created a devastating explosion over North America, laying waste to forests and Native American villages alike. Researchers found evidence of a cosmic airburst at 11 Hopewell archaeological sites in three states stretching across the Ohio River Valley.


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New comet C/2021 O3 Might Brighten in May 2022
1/20/2022

A comet discovered last July is approaching the inner solar system and might reach binocular visibility (at least) by late April and early May 2022. It’s designated C/2021 O3 (PanSTARRS) and appears to be “new” to the inner solar system, a first-time visitor. If it survives its April 2022 passage near our star, the comet might become visible to amateur stargazers armed with binoculars in May. At that time, it’ll be in front of the constellation Perseus the Hero, close to the northwestern horizon after sunset.


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