Discovering the Universe
Explore the concepts that underlie the study of the stars and other heavenly bodies, and how astrophysicists analyze their distant light for clues to their physical and chemical properties. This Special Collection sets out the fundamentals and demonstrates them in a set of articles, activities, and reference lists for all ages.
Did you know that when you look at a star, your eyes are capturing light that traveled all the way from the star to your eye? Learn more about how light carries information from distant objects.
You can't see the Sun's ultraviolet rays with your eyes—you just see their results on your freckled, tanned, or sunburned skin. Build a bracelet that immediately detects these invisible rays.
When does mixing every color under the rainbow create pure white rather than a murky brown or black? When light, not paint, is the medium—and you're subtracting, not adding, color.
White light is a mixture of all colors of visible light, but it doesn't always include every color of the rainbow. Build a spectroscope, and view the spectral fingerprints of different light sources.
It probably comes as no surprise that telescopes do a better job of collecting light and observing outer space than your eyes. But do you know why? (Hint: the answer is NOT magnification!)
While refracting and reflecting telescopes use different means of collecting light, the same principle applies to both—the bigger the aperture, the more light collected.
What could Galileo see when he looked through his telescope? Build a refracting telescope with lenses similar to the ones he used, and see the answer for yourself.
What is a telescope's focal point, and why is knowing its location so important to astronomers? Grab a flashlight, an empty soda bottle, and a few other supplies; then find out.
For most of human history, recording a star meant describing it with words or drawing a picture. The 19th-century invention of photography changed that—only to be revolutionized by digital imaging.
No doubt you've received—or even sent—a digital image. But do you know how these pixel-based photographs work? You will after you decode one yourself.