What Is "Special" about the North Star?

Question

Question for science exam...please help

Answer 1

The North Star is a title of the star best suited for navigation northwards. A candidate must be viewable from Earth and circumpolar to the north celestial pole. The current one is Polaris. It is the star at the end of the "handle" of the Little Dipper asterism in the constellation Ursa Minor. It is close to the celestial North Pole, but off by about two-thirds of 1°.

The North Star has been historically used by explorers to determine their latitude. At any point north of the equator the angle from the horizon to the North Star (its altitude) is the same as the latitude from which that angle was taken. For example, the angle to the North Star for a person at 30° latitude will be about 30°.

Polaris has a visual magnitude of 1.97 (second magnitude). Although some people mistakenly think this is the brightest star in the night sky (which truly belongs to Sirius), there are many others that are brighter.

Due to the precession of the equinoxes the direction of the Earth's axis is very slowly but constantly changing, and as the projection of the Earth's axis moves around the celestial sphere over the millenia, the role of North Star passes from one star to another. Since the precession of the equinoxes is so slow, a single star typically holds that title for many centuries.

In 3000 BC the faint star Thuban in the constellation Draco was the North Star. At magnitude 3.67 (fourth magnitude) it is only one-fifth as bright as Polaris, the current North Pole Star (situated at 430 light-years away)

Gamma Cephei (also known as Alrai, situated at 45 light-years away) will become closer to the northern celestial pole than Polaris around 3000 AD, and be at its closest approach around 4000 AD. The "title" then will pass to Iota Cephei (ι Cephei, situated 115 light-years away) some time around 5200 AD. The first magnitude star Vega (26 light-years away) will then become the North Star by 14000 AD.

Currently, there is no South Star as useful as Polaris; the faint star Octantis is closest to the south celestial pole. However, the constellation Crux, the Southern Cross, points towards the south pole.

Answer 2

The North Star, also known as Polaris, is like all the other stars we see in our night sky – they’re all members of the Milky Way galaxy. All the stars are moving through space – but they’re so far away we can’t easily see them move relative to each other. That’s why the stars appear “fixed” – it’s why we see the same constellations as our ancestors.

But Earth spins underneath the stars once a day. Earth’s spin causes the stars to rise in the east and set in the west, just as the sun does. When you’re talking about this kind of movement, the North Star is a special case. It lies almost exactly above Earth’s northern axis. So Polaris is like the hub of a wheel. It doesn’t rise or set – instead, it appears to stay put in the northern sky. Polaris cannot be seen from the Southern Hemisphere (unless you're right at the equator and on an elevated vantage point). Polaris is estimated to be within 1/2 degree in 2100 when it become an even more accurate "north star."

That’s how the eye sees it, anyway. The North Star is really offset a little from celestial north. If you took its picture, you’d find that it makes its own little circle around true north every day. What’s more, the star we know as Polaris hasn’t been the only North Star.

A motion of Earth called precession causes our axis to trace out an imaginary circle on the celestial sphere every 26,000 years. Thousands of years ago, when the pyramids were rising from the sands of ancient Egypt, the pole star was an inconspicuous star called Thuban in the constellation Draco the Dragon.

Twelve thousand years from now, the blue-white star Vega in the constellation Lyra will be a much brighter pole star than our current Polaris. Polaris could be a name for any pole star. Our current Polaris used to be called Phoenice.

Answer 3

The North Star, also known as Polaris, is with-in a half of a degree of being directly over the Geographic North Pole. Hence, the name North Star.

Answer 4

Its very close to the north celestial pole, so is used to find north (especially useful to ancient sailors that had no landmarks to use to guide them).
Its a triple star system - the primary is a yellow Cepheid variable, with 2 dwarf star companions.
Polaris is gradually increasing in brightness (not by much, it was mag 3 in Ptolemy's time and is mag 2 now).

Answer 5

Copernicus II is right. There is no South star worthy of the name. There are no especially bright stars near the South celestial pole, and furthermore, there will not be one for 13,000 years ( see precession) The celestial poles are where our planet is pointing as it spins in space.

Answer 6

The axis of the earth points almost directly at this star, it is easy to find, this makes it a great aid to navigation.

Answer 7

It pretty much doesn't move, but all the other stars do. Polaris is above the Earths axis.

Answer 8

It moves very little in the sky. To they eye it is virtually stationary compared to all the other starts. It's always there in basically the same place the sky, every night.