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Scorpius X-1

July 22, 2016

Most of us are familiar with X-rays because doctors and dentists use them to diagnose problems with our bodies and teeth. But X-rays are also a natural phenomenon in the universe. And just as medical X-rays reveal details about our bodies, these natural X-rays reveal details about astronomical bodies.

An X-ray carries far more energy than visible light does. So X-rays often alert astronomers to extreme stars. In fact, the first black hole ever found gave itself away because gas falling into it emits X-rays.

But the brightest X-ray source outside our solar system isn’t a black hole. Instead, it’s a neutron star — the crushed core of a once mighty star. It’s only about a dozen miles across, but it’s more massive than the Sun. So if you could somehow stand on its surface, you’d weigh trillions of pounds. And if you dropped a pebble from a height of a few feet, it would smash into the surface at millions of miles per hour.

The neutron star is in the bright constellation Scorpius, which is in the southern sky on July evenings. In the 1960s, a rocket detected a source of X-rays there, so scientists named it Scorpius X-1 — the first source of X-rays in Scorpius. The X-rays come not from the neutron star itself, but from a disk of gas around it. The gas is heated to millions of degrees, so it produces X-rays.

Scorpius X-1 is the brightest X-ray source beyond our solar system — high-energy radiation warning spacefarers of an extreme star dead ahead.

Script by Ken Croswell, Copyright 2016

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