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This is an artist's depiction of Polaris in the constellation Ursa Minor.
Click on image for full size
NASA, ESA, G. Bacon (STScI)

Polaris is Big!
News story originally written on June 14, 2000

Scientists using a new telescope have calculated the actual size of the North Star, otherwise known as Polaris. It turns out that Polaris is 46 times larger than the Sun. It is no surprise to scientists, because Polaris is a cepheid star.

Cepheids are special stars that pulsate at a constant period. In other words, cepheids get brighter for a short time because there size changes. The complex make-up of the stars creates this effect. Cepheids are known to be much larger than normal stars like the Sun.

Polaris is one of the most famous stars in our night sky. The North Star is almost directly above the Earth's North Pole, so the position of the star changes only slightly during the year. Sailors used Polaris to guide them on the open seas. Today we know Polaris as the last star in the constellation Ursa Minor, or the Little Bear.

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA