Richard San Roman, age 11, of Sarasota, Florida, for his question:

Can you describe Alpha Centauri?

This bright golden star which can be seen in the skies above the Southern Hemisphere actually consists of two stars revolving around each other. A third much dimmer star, Proxima Centauri, also circles in this system. The two stars of Alpha Centauri each have a mass almost equal to that of our sun. Experts classify Alpha Centauri as a "visual binary star" because its two separate members can be distinguished through the telescope.

In our Galaxy, way out from the crowded central hub on a spiraling arm, the stars are strewn rather thinly. Within a range of 10 light years from the sun, there are less than 15 other stars. And one of the closest is Alpha Centauri. This star is at a distance of approximately 4.3 light years    each light year being about six million -million miles. Traveling at the speed of light, 186,000 miles per second, a spacecraft could get from here to there in four years, four months.