The North Star, also known as Polaris or the Polar Star seems to never move. How do we know that? Photography. It appears that when a camera is set up and takes photos over a period of time, the stars make a "wheel". The point, or focus of that wheel is our North Star. This is one reason when hiking at night we can use the North Star to find North. Sea captains also used the North star to navigate across the oceans when traveling because they could see true north. Our Earth has a tilt, and that imaginary axis that demonstrates our tilt and rotation points to the North Star. The North Star is special. Because it lies almost exactly above Earth’s northern axis, it’s like the hub of a wheel. It doesn’t rise or set. Instead, it appears to stay put in the northern sky. When you take a time lapse picture of this phenomenon, the north star does look like the hub of a wheel. There's something else about the North Star.... The North Star does move. If you took its picture, you’d find that it makes its own little circle around the exact point of the north celestial pole every day. That’s because the North Star is really offset a little – by about three-quarters of a degree – from celestial north. And there's more... The single point of light that we see as Polaris is actually a triple star system, or three stars orbiting a common center of mass. The primary star, Polaris A, is a super giant with about six times the mass of our sun. A close companion, Polaris Ab, orbits 2 billion miles from Polaris. Much farther away, near the top of the illustration, is the third companion Polaris B. Polaris B is located approximately 240 billion miles from Polaris A. Astronomers estimate Polaris’ distance at 430 light-years. Polaris is a yellow super giant star shining with the luminosity of 2500 suns. Bottom Line: In our lifetime, we don't live long enough to see Polaris change places in the sky because it is SO FAR AWAY. From our point of view in time, we don't see any movement at all. Which is great because the star, or stars, have helped us navigate around the Earth for a very long time. If you want to see the North Star look for the Big Dipper and follow its pointer stars to the tip of the handle of the Little Dipper. The North Star is not the brightest star in the night, but it is the only constant star that you can rely on for many years to come.
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Mrs. TaylorI love science! Everything about the world is interesting and never boring. I love to study plants, animals, insects, and people. My favorite subjects are my students who are the most unique organisms on the planet! Categories |