Rhonda North, age 10,of Salt Lake City, Utah, for her question:
HOW FAR IS THE NEAREST STAR?
The stars, of course, are those twinkling sparklers that shine at night in the dark, velvety sky. All of them are vast distances away, across the vast ocean of space. But let's not forget our very own personal star, the dazzling sun. Its distance is only about 93 million miles, which is much closer to us than any of the nighttime stars.
Outer space is so enormous that a million earth miles is but a tiny step. Obviously we need a larger unit to measure the distance between us and the night time stars. One of the sky's measuring units is the light year. Not counting the sun, the nearest star to us is a distance of 4.3 light years.
Unless we know more about the light year, this figure does not mean very much. This clever measuring unit is somewhat like so many miles per hour. It is based on the speed of light, which is roughly 186,000 miles per second or almost 700 million miles per hour. But this is not all The stupendous light year is the distance that light travels in one earth year, one light year equals about 6 million million ordinary earth miles. You can write this figure as 6 plus a tail of 12 zeros. The nearest star, not counting the sun, is about 27 million, million miles away or 4.3 light years.
It would be nice to look up and see our nearest neighbor in the starry sky. But this star does not shine in our skies. It appears in the Southern Hemisphere, south of the equator. There it is the brightest star in the constellation Centaurus, the Centaur.
Astronomers use the Greek alphabet\to,list the stars of a constellation according to their brightness. our nearest neighbor is Alpha Centauri, the brightest sparkler in Centaurus. Actually it is a close family of several stars. The one that is closest to us is called Proxima.
We cannot see the nearest star, but we can see the second nearest. It is Sirius, the dazzling Dog Star that shines in our winter skies. Its distance is 8.6 light years, which is twice as far as Alpha Centauri. But Sirius is bigger and much brighter. In fact, it is the brightest star seen from anywhere on the earth not counting our razzle dazzle starry sun.