Visible light, which can be seen with our eyes, comprises a small sliver of the electromagnetic spectrum. The rest of the spectrum, from short wavelength gamma rays to long-wavelength radio waves, requires special instruments to detect. ALMA uses and array of radio telescopes to detect and study radio waves from space. Radio telescopes are typically large parabolic dish antennas used singly or in an array. Radio observatories are preferentially located...

Using the laws of physics and electromagnetic radiation, astronomers can "weigh" a galaxy by studying the distribution of its rotating hydrogen. But when they do this, it soon becomes clear something is very wrong: A huge proportion of the galaxy's mass has simply gone missing. Welcome to the topsy-turvy world of dark matter - which we now believe accounts for 90 percent of our own Milky Way.

With an array of 66 radio antennas located in the high Chilean desert above much of the earth's atmosphere, the Atacama Large Millimeter/submillimeter Array (ALMA) is a radio telescope tuned to the higher frequencies of radio waves. Designed to examine some of the most distant and ancient galaxies ever seen, ALMA has not only revealed new stars in the making, but planetary systems as well.

Dig deeper into the treasure trove of data from the Kepler mission, which discovered hundreds of compact multiplanet systems, with planets much more closely packed than in our solar system. Explore the dynamics of these groupings, which have planets interacting strongly through mutual gravitation..

The spectacular sights of the cosmos are now as easy to see as the stars above, with these lavishly illustrated episodes produced in partnership with the Smithsonian. Orbit Saturn, search for water and life on Mars, and witness an armada of space telescopes uncovering the secrets of the cosmos. Embark on great voyages of discovery and enjoy a view that's truly out of this world!

The Green Bank Observatory is located within the 13,000-acre National Radio Quiet Zone straddling the border of Virginia and West Virginia. Come tour this fascinating facility where astronomers discovered radiation belts around Jupiter, the black hole at the center of our galaxy, and the first known interstellar organic molecule, and began the search for extra-terrestrial life.

In billions of years, the Sun will expand into a red giant, possibly engulfing Earth. Learn how planet-finding techniques give astronomers insight into the processes inside giant stars. Then study the planets around these behemoths for clues about Earth’s ultimate fate..

In visible light, scientists had described galaxies as "island universes." But since the advent of radio astronomy, we've seen galaxies connected by streams of neutral hydrogen, interacting with and ripping the gasses from each other. Now astronomers have learned hat these strong environmental interactions are not a secondary feature - they are key to a galaxy's basic structure and appearance.

Focus on two enigmatic ice worlds: Jupiter's moon Europa and Saturn's moon Enceladus. Both may harbor liquid water beneath their icy crusts. Weigh the chances that life exists in these underground oceans, despite the extreme cold in the outer solar system.

Learn how astronomers use very-long-baseline interferometry (VLBI) with telescopes thousands of miles apart to essentially create a radio telescope as big as the Earth. With VLBI, scientists not only look deep into galactic centers, study cosmic radio sources, and weigh black holes, but also more accurately tell time, study plate tectonics, and more - right here on planet Earth.