Season 4 opens with an exploration of dying stars, the process where stars become supernovas, and, occasionally, become the biggest blast in the universe as a gamma ray burst (GRB). One death star, named WR104, lurks 8,000 light-years from Earth and some believe its GRB arrow is aimed directly at us. A death star galaxy named 3C321 is a frightening vision of what could one day befall the Milky Way galaxy: a companion galaxy's black hole being hammered with a constant blast of high-energy particles, wreaking havoc with its celestial bodies

Without the moon, Earth would be a very different and desolate place today--four hours of sunlight with pitch-black nights, steady 100-mph winds spawning giant hurricanes that last for months, and virtually no complex life forms, much less humans. Safe to say, we probably owe our very existence to the moon. But what if it suddenly disappeared?

Every year, thousands of objects both natural and manmade plummet through our atmosphere and crash into the Earth. These menacing messengers from the sky provide scientists with amazing insights into the natural, and not so natural, phenomena of the cosmos. From space rocks crashing through homes to cosmic boulders triggering mass extinctions to rocket parts landing on front lawns, explore objects that fall from the heavens, such as asteroids, comets, meteor showers and space debris

An examination of the most powerful explosions and blasts in the universe. Includes a look at the Mexico's Yucatán peninsula and the impact which caused the Chicxulub crater. Also a look at gamma rays and Big Bang Theory

They are breathtaking, lethal and a constant source of surprise. The stunning rings of Saturn have mesmerized countless scientists over the centuries. With particles the size of a house shooting at 53,000 miles per hour around the planet, any spacecraft passing through would meet an instant and catastrophic end

Experts cook up ways you could destroy the Earth, including swallowing it with a black hole, blowing it up with anti-matter, hurling it into the Sun, and switching off gravity

They are the one-stop-shopping places for learning all about the nature and variety of stars in the Universe. They're unique, because in clusters, all the stars were born at about the same time, from the same material and all are at the same approximate distance from Earth. This means we can be sure that any differences among them are due to their true natures and not distorted by different distances from Earth and other factors

Outer space is already an essential part of America's ability to fight wars. Our military depends on satellites for many things, such as communications, reconnaissance and targeting information. But so far, no country has put weapons into space, although the U

On alien planets, they rain from the sky as scalding iron. On distant moons, even at hundreds of degrees below zero, they slosh around in pristine lakes of methane. They can cover entire planets in miles-deep oceans of electrified hydrogen metal

They sort of sound like the same phenomenon, but Pulsars and Quasars are very different. Pulsars are tiny--only a few miles across--but they spin as fast as a kitchen blender and sweep the sky with beacons of radiation that make them appear to flash on and off. They have unbelievably strong magnetic fields, are more accurate than atomic clocks

Warp speed, transporters, wormholes and lasers--they are all staples of science fiction books, movies, and TV shows. But the fantastic world of tomorrow is quickly becoming the futuristic world of today. While you may not be "beaming" to your next appointment any time soon, researchers are preparing for the first tests of a present-day "transporter

Ours is a universe of energy, from powerful jets ejected from black holes to the raw nuclear fury of our Sun. But, the total amount of energy in the universe maintains perfect equilibrium--no more can be added or taken away. Because of this, there are enormous amounts of energy being transferred