Hobbies And Interests
Identification
The light from a star often seems to be moving back and forth a bit. This is caused by the light from the star passing through the Earth's atmosphere and being bent, or refracted. The light is moving through various layers of air that can be different temperatures and density, causing the star to "twinkle." Planets do not twinkle because they are closer to Earth and they appear large enough to offset the twinkling effect. Stars overhead twinkle less than those close to the horizon due to the fact they have to traverse through more air than they do directly above us.
Time Frame
The naked eye can detect only about 5,000 stars. Of those, only a fraction can be seen at any given time from a given place. A small telescope will reveal thousands of stars, and the highest-powered telescopes can show millions. Stars are so distant from Earth that this distance is measured in what are called light years, the distance that light would travel in one year. The closest star other than the sun is Proxima Centauri, which is more than four light years away. This means that when you see the light from this particular star, it started out from the star four years before.
Types
The color of stars depends on their temperature. Blue-white stars have a temperature of over 36,000 degrees. White stars are from 20,000 to 36,000 degrees. Yellow stars are 11,000 to 20,000 degree, with orange stars from 7,500 to 11,000 degrees. The coolest stars are the red ones, about 5,500 degrees.
Features
Even though our sun is 93 million miles away, it still appears to us as a large orangish ball of glowing gases. The sun could be described as an average star, and the majority of stars would appear to us just as the sun does. Stars do differ in size, though. For example, Antares, a red-giant star, would extend out well past the orbit of Earth if it were to replace our sun. Also, some stars are much denser than others.
Considerations
When the ancient civilizations looked into the sky, they saw various shapes and figures when they connected some of the stars. These star groupings are called constellations. Some are familiar, such as Orion the Hunter, which shines brightly in the Northern Hemisphere winter night. Others are obscure, looking very little like what they are supposed to represent.