Explaining Those Mysterious Lights in Space
Stars Are Not the Only Thing Visible in the Night Sky
by Pallav Regmi, age 12
Stars are everywhere in the universe. They can be seen all over the night sky. But how do they start? How do they end? The mysteries of the skies have fascinated astronomers for generations.
Stars are formed when plasma, a hot gas-like substance, and gas are held together by gravity. Years ago, when a new, bright light appeared in the sky, people thought it was the birth of a new star, and named it nova or “new.” Actually, it was the product of a white dwarf star exploding.
Novas are very bright and look like new stars. Even more unique is the appearance of supernovas, which are even brighter than novas. A supernova may only occur once every few hundred years. In the year 1054, Chinese astronomers saw a supernova in the constellation of Taurus. Today, the gaseous remains of this star are called the Crab Nebula.
Some supernovas vanish completely, leaving behind only the wispy gases of a nebula. However, a few supernovas leave a small, tightly packed ball of particles called a neutron star, which is incredibly massive. A tiny drop of a neutron star would weigh a billion tons on earth.
If a supernova suddenly collapses, the neutron star would start to spin very fast, emitting beams of X-ray radiation. Because X-ray radiation can be detected as a pulse, like a lighthouse beam, it is called a pulsar. There is a pulsar in the Crab Nebula; the star is visible when the pulsar blinks on and off at a rate of 30 times a second.
If a giant star collapses, it is crushed together by collapsing gases. The star disappears after gravity squeezes it too much, and becomes a black hole. Even light cannot pass through black holes. Black holes are invisible and almost impossible to find. Anything lingering too close to a black hole will be sucked in and stuck there for eternity.
The night sky is bright with stars, planets, nebulas, and even novas or supernovas. In a few minutes of thoughtful watching, you too can see the fascinating displays that happen out in the cosmos.
[Sources: Stars, www.nasa.gov]