Have you ever wondered what color is? In this first installment of a series on light, Colm Kelleher describes the physics behind colors — why the colors we see are related to the period of motion and the frequency of waves.

There are three types of color receptors in your eye: red, green and blue. But how do we see the amazing kaleidoscope of other colors that make up our world? Colm Kelleher explains how humans can see everything from auburn to aquamarine.

Just as color is subjective among humans, so too are the colors in the stunning images our robotic spacecraft send back to Earth. Cameras on our space probes act as proxies for our own eyes, but what they see isn’t necessarily what our eyes would see. The Planetary Society explores why the true colors of the planets aren’t what you think.

Revisit the Voyager 2’s flyby of Neptune, or find out how scientists mapped Venus using radar.

In 1995, scientists pointed the Hubble Telescope at an area of the sky near the Big Dipper. The location was apparently empty, and the whole endeavor was risky – what, if anything, was going to show up? But what came back was nothing short of spectacular: an image of over 1,500 galaxies glimmering in a tiny sliver of the universe. Alex Hofeldt helps us understand the scale of this image.

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