Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2023 September 5
A large Moon is seen behind a historic stone structure. 
Please see the explanation for more detailed information.

Blue Supermoon Beyond Syracuse
Credit & Copyright: Kevin Saragozza

Explanation: The last full moon was doubly unusual. First of all, it was a blue moon. A modern definition of a blue moon is a second full moon to occur during one calendar month. Since there are 13 full moons in 2023, one month has to have two -- and that month was August. The first full moon was on August 1 and named a Sturgeon Moon. The second reason that the last full moon was unusual was because it was a supermoon. A modern definition of supermoon is a moon that reaches its full phase when it is relatively close to Earth -- and so appears a bit larger and brighter than average. Pictured, the blue supermoon of 2023 was imaged hovering far behind a historic castle and lighthouse in Syracuse, Sicily, Italy.

Gallery: Selected August 2023 supermoon images submitted to APOD
Tomorrow's picture: sky in motion

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