Ultima Thule

In ancient times the northernmost region of the habitable world - hence, any distant, unknown or mysterious land.

Thursday, October 19, 2006

Warning! Staring at this picture may make you dizzy!

By Aussiegirl

This short article mentions the fact that Polaris won't always be the North Star. The reason for this is the precession of the equinoxes, and for a discussion of this phenomenon (in which we learn that Polaris will again become the North Star in 27800 A.D), please see my earlier post here.

SpaceWeather.com -- News and information about meteor showers, solar flares, auroras, and near-Earth asteroids

These are star trails--slow, graceful arcs traced by the stars as Earth spins on its axis. "It was a clear night last night, so I decided to let my camera do an 'all-nighter,'" explains photographer Larry Landolfi of Rochester, New Hampshire. "I made this 8-hour exposure of my house looking towards the North Star."

The North Star, a.k.a. Polaris, is the stubby arc near the pattern's vertex. Because Earth's north pole points almost directly at Polaris, the star barely moves throughout the night, making it useful for direction-finding. But Polaris won't always be the North Star. Earth's spin axis is slowly precessing, and in 10,000 years or so Vega (six times brighter than Polaris) will take over as North Star. Star trail photos will look even prettier then, with an intense bright dot in the center of the starry whirlpool.


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