[SFX: Pulsar sounds] Those are the voices of pulsars — the corpses of exploded stars. More than 2,000 have been discovered so far. But several projects are looking for more.

A pulsar forms when a massive star dies. The core collapses into a ball no bigger than a city, but up to twice as massive as the Sun. As the pulsar spins, a powerful magnetic field generates beams of energy. They can sweep across Earth like a lighthouse, producing “pulses” of radio waves and other forms of energy.

The timing of a pulsar’s “beat” can reveal the location, mass, and size of a pulsar. That tells astronomers how such stars form and evolve. It also can reveal the presence of a companion star or planet, and details about the companion. And changes in timing might even reveal gravitational waves rippling through the universe.

One major search is being conducted with the giant Arecibo radio telescope in Puerto Rico. The search has revealed more than 200 pulsars. Many of those were discovered by students at universities in Texas and Wisconsin. The students have sifted through observations compiled over many years.

Another major search uses the Green Bank Telescope in West Virginia. It involves students from high schools and colleges across the country. The students learn about how science works, while astronomers get new pulsars to ponder — rotating beacons throughout the galaxy.

Script by Damond Benningfield