Felix J. Lockman

Not long after the birth of radio astronomy, a Dutch student used what was then known about the physics of atoms to determine that if hydrogen existed in interstellar space, it would produce a specific spectral line at radio wavelengths. In 1951, the line was detected at 21 cm, exactly as predicted. At that moment, our understanding of the universe forever changed.

Interstellar clouds favor formation of carbon-based molecules over any other kind - not at all what statistical models predicted. In fact, interstellar clouds contain a profusion of chemicals similar to those that occur naturally on Earth. If planets are formed in this rich soup of organic molecules, is it possible life does not have to start from scratch on each planet?

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.

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.

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.

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.

Before there were stars and planets, before there were galaxies, there was hydrogen - and we still have more hydrogen today than any other element. Understanding the quantum physics of this simplest atomic structure, and using the Doppler shift and models of differential rotation in the Milky Way, astronomers have made myriad astounding discoveries about the universe. It all starts with hydrogen.

Have you ever looked up to Orion on a dark winter's night and noticed a fuzzy patch near the center of the constellation? You're looking at the Orion nebula, a "nursery" where stars are born every year. Learn why ionization occurs in these H II regions and how this hot plasma produces some of the most beautiful objects in the sky.

Radio source counts have led to great discoveries about the universe, even though each individual radio source isn't fully understood. Between massive black holes and starbursts, scientists relying in part on astronomical surveys now believe galaxies can have different evolutionary tracks and histories. And the universe itself? It seems to be not only evolving, but evolving through stages.

When young engineer Karl Jansky was tasked to find natural radio sources that could interfere with commercial transatlantic radio communications, radio astronomy was born. His work led to the discovery of synchrotron radiation. But it would be decades before scientists understood what these earliest radio astronomers had detected - cosmic rays and magnetic fields.