
Amateur Astronomers Help Scientists Map Over 42 Million Stars
Image: The open cluster in the Tarantula zone
Amateur and professional astronomers have produced a star catalog that measures the detailed characteristics of more than 42 million stars, many of which are accurately mapped for the first time in history.
The catalog is focused on variable stars, a large and diverse class of stars that change in brightness over time. Astronomers need good information about variable stars to learn details about the lives of stars — such as their mass, temperature, and internal structure — that would otherwise be difficult or impossible to determine.
The survey comes from the American Association of Variable Star Observers (AAVSO), an international nonprofit organization of star observers that has been collecting data for this map since 2009. This latest release, which was made publicly available on June 8, covers 95 percent of the northern and southern sky. The project is expected to be complete in 2014.

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