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Credit & Copyright: Bray Falls
Explanation:
Why is Polaris called the North Star?
First,
Polaris is the nearest
bright star toward the north
spin axis of the Earth.
Therefore, as the Earth turns, stars appear to revolve around Polaris,
but Polaris itself always stays in the same northerly direction -- making it the
North Star.
Since no bright star is near the
south spin axis of the Earth, there is currently
no
South Star.
Thousands of years ago, Earth's spin axis pointed in a slightly different direction
so that
Vega was the North Star.
Although Polaris is not the brightest star on the sky,
it is easily located because it is
nearly aligned with two stars in the cup of the
Big Dipper.
Polaris is near the center of the eight-degree wide
featured image, an image that has been
digitally manipulated to suppress surrounding dim stars
but accentuate the faint gas and dust of the
Intergalactic Flux Nebula (IFN).
The surface of
Cepheid Polaris slowly
pulsates,
causing the star to
change its brightness
by a few percent over the course of a few days.
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NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day
Publications with keywords: polaris
Publications with words: polaris
See also: