- What Your Eyes See:The
human eye only sees visible light. Sometimes scientists call this the optical range
of light. This has been the most studied wavelength. Astronomers will often work
in the "blue end" if they are interested in slightly hotter stars or the
"red end" for cooler ones.
- What are Good Sources of Visible Light? When a star ages, its outer envelope can expand to 50 times its normal
size. When it expands, it cools and looks red. It is then called a "red-giant"
star. You can see that stars have different colors by looking at the constellation
Orion this Fall. The star to the north is the red-giant Betelgeuse, compare how it
looks to the star in the lower right corner of Orion, which is Rigel a hotter younger
star. Other objects frequently observed in visible light are the Moon, solar system
objects (Mars, Venus, our Sun, etc.), stars, and other galaxies.
- Of course, we see all sorts of things on Earth. The Sun's light
we see reflected off of objects on Earth is visible light. Because visible light
reaches us, we can observe objects like the Sun, the Moon, planets, and stars from
ground-based telescopes. Some famous visible light telescopes are, Keck Telescope
in Hawaii, Kitt Peak National Observatory in Arizona, and Cerro Tololo Inter-American
Observatory in Chile
- Here's Some Easy-To-Do Visible Light Activities at the Exploratorium. (Will appear in your second window)
- Keck Observatory atop Mauna Kea on the Big Island of Hawaii. The Keck Telescope
is eight stories tall and 300 tons in weight.