SATR FACTS

STAR FACTS

Stars seem to twinkle because we see them through the layers of the Earth's atmosphere. As light passes through these layers, it is distorted so that the amount we actually see changes constantly. The stars nearest the horizon appear to twinkle the most because the light is passing through a greater depth of atmosphere. Stars do not twinkle when viewed from space, which is why telescopes in space, such as the Hubble, give the best possible view of distant stars and galaxies.

A star is a luminous body of gas, mostly hydrogen and helium. Stars generate light, which makes it possible for us to see them with a telescope or the naked eye. They also release energy from nuclear fission reactions in their core.

Brightest

Not counting the Sun, the brightest star as seen from Earth is Sirius, known as the dog star, in the constellation of Canis Major. It has a diameter of 149,598,020km and is more than 24 times brighter than the Sun. The star Cygnus OB2 No 12, discovered in 1992, is so far away that it cannot been seen from Earth. It may be the brightest star in the galaxy—up to six million times as bright as our Sun. 

Heaviest

 HDE 269810 is a star in the Large Magellanic Cloud-170,000 light years from Earth (a light year is the distance light travels in a year). It has been discovered by the Hopkins Ultraviolet telescope to be 190 times as heavy as our Sun.

Largest

The largest star is the M-class super giant Betelgeuse, or Alpha  Orionis. It is the top left star in the constellation of Orion, which is 310 light years away. It has a diameter of 700 million km, which is about 500 times greater than that of the Sun.

Nearest

Proxima Centauri, discovered in 1915, is 4.22 light years (39,953,525.879,212km) from Earth. A spaceship moving at 40,000km/h—which is faster than any human has yet travelled in space - would take more than 114,000 years to reach it.

Supernovae

These are vast explosions in which a whole star is blown up. They are extremely bright, rivalling for a few days the combined light output of all the stars in the galaxy. Supernovae are rare— the last one in our galaxy was seen in 1604 by the German astronomer johannes Kepler.

Quasars

Quasars are extremely distant radio galaxies-galaxies giving out large amounts of radio energy — and the brightest objects in the Universe. Even those near the most distant edge of the observable | Universe are easily detected by small radio telescopes. Their radio emission is typically 1,000,000 to 100,000,000 times greater than that of a normal galaxy, and they are as bright as or brighter than the brightest radio galaxies.

Black holes

A black hole is a star that has collapsed into itself. It has a surface gravity so powerful that nothing can escape from within it.