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Not every star is constant. Believe it or not, one of the most famous points of light, the North Star is not actually constant, it too, changes its brightness every so often. It brightens slightly and fade slightly over and over with the passing years. Researchers are learning what this signifies. And just lately, astronomers at Villanova University concluded that the North Star has brightened by about a single magnitude, about 2.5 times since antiquity.

Variable stars come in two basic types. Thi first is called the Intrinsic which often change in brightness due to physical alterations in the stars themselves. They break down into 3 main groups, which are the Pulsating, the Flare and the Exploding stars. The second form of variable star has the name the Extrinsic that apparently alters in brightness due to the fact something outside the star changes its light. Both the intrinsic and extrinsic variable stars would be the Eclipsing binaries and the Microlensing event stars.

Pulsating stars are in a continuing state of oscillation, they bulge in and out, getting bigger and smaller, hotter and cooler, brighter and dimmer.

Cepheid Variable stars are a vey important pulsating type, from the scientific perspective, they inherited their label as a result of the first studied star of their kind, the Delta from the constellation Cepheus consequently the name became Delta Cephei. Cepheids are located in faraway galaxies.

Knowing the real brightness connected with a star makes it possible for us to find out the distance of it. Of course, the further away it is, the dimmer it looks, nevertheless in reality, it still possesses the same true brightness.

If a star is two times as far away, it appears four times as faint, if the distance is tripled, then it looks nine times as faint, and
if it is ten times further away, it seems one hundred times as faint.

RR Lyrae stars are almost like Cepheids although not as large and bright. A number are located in globular star clusters inside our Milky Way.

Globular clusters are large balls of old stars that have been born while the Milky Way was still forming. With globular clusters, there are some hundred thousand to a million or so stars all crammed in a section of space only 60 to 100 light-years across.

Flare stars are small red-colored dwarfs that experience huge explosions, like ultrapowerful solar flares. You can not see most solar flares without the aid of a special colored filter, since the light from the flare is just a very small fraction associated with the total light from the sun.

Exploding stars are know as the novas and supernovas. These explosions are massive. They are significantly more powerful and also have considerably greater effects then the flare does. A nova explodes through a build-up process on a white dwarf in a binary system. It merely blows its top and then it settles down while it sucks more gasses off its companion and on its surface layer.

Classical novas, dwarf novas, and similar objects are known collectively as cataclysmic variables.