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 February 2025
2/6/2025
It’s been a wild last few months for comet observers, with not one but two comets reaching negative magnitudes. Though both C/2023 A3 (Tsuchinshan-ATLAS) and C/2024 G3 (ATLAS) were at their brightest when within a few degrees of the Sun, both were observable in bright twilight and were still close to 0th to 1st magnitude as they entered a dark sky.
In February, C/2023 A3 (Tsuchinshan-ATLAS) fades from 10th to 11th magnitude for northern hemisphere observers. C/2024 G3 (ATLAS) is still a naked-eye object with a tail up to 10 degrees long, but only for southern hemisphere observers. The comet's continued brightness and photogenicity are amazing since the nucleus of ATLAS disintegrated around January 19/20, about a week after perihelion. The only other comet currently brighter than magnitude 12 is the outbursting Centaur comet 29P/Schwassmann-Wachmann, which is near opposition in Leo this month.
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/953681-alpo-comet-news-for-february-2025/
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Meteors Shed Light on Comet Composition
8/22/2024

Physics.org logo 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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