Education
Learn the basics of light, lenses, and telescope designs.
What is light
Visible light is electromagnetic radiation with wavelengths roughly between 380 nm (violet) and 780 nm (red). Wavelength determines the color we perceive. Drag the slider to see how color changes across the visible spectrum.
Note: The colors shown may not exactly match the wavelength stated; this demo is intended to illustrate the visible spectrum.
How does a lens work
A positive lens bends parallel (collimated) rays toward a single point called the focus. The distance from the lens to that point is the focal length.
How does a Schmidt–Cassegrain telescope work?
Light enters through a Schmidt corrector plate (which corrects spherical aberration), hits the primary mirror at the back, reflects to the secondary mirror, then passes through a hole in the primary behind the tube.
Constellation Challenge
Test your knowledge of the night sky! Can you identify these famous constellations? Each pattern represents actual star positions.
Which constellation is shown above?