What Are UFO's?

The popular name for them is "flying saucers". UFO stands for "unidentified flying object".

Do they really exist? Many books have been written about them and thousands of people claim they have seen them; some even claim they have photographed them. And no matter what scientific investiga­tions reveal, there will still be people who believe they exist.

Studies of saucer reports show that UFO's are very different from one another. Some people report having seen flat saucers; others see saucers shaped like spheres, cigars, or doughnuts.

The colours of saucers seem to be as different as their sizes. Saucers of nearly all colours have been reported. Some seem to change colour as they are being watched.

Saucers have been seen to move in every direction and at nearly every speed. They can turn at right angles, move straight up or straight down, or travel in a zigzag path. They can hang motionless in the air, and make either a hissing noise or a roar.

When the United States Air Force started to investigate the re­ports about flying saucers, it discovered that people weren't "imagin­ing" what they saw. Everyone who reported a flying saucer had seen something. But what?

In some cases, the "something" was actually a weather balloon. In other cases, it was a satellite, a cloud, a meteor, a star, a bird, a comet, a planet, or fireworks. It was also what are called sun dogs. These are images of the sun reflected through ice crystals. Many flying- saucer stories have been traced to fireballs, which are formed by lightning.

If saucers were really spaceships, there would be a certain pat­tern in the reports about them. But there is no such pattern. The rea­son is that people are not seeing spaceships but many other things. So scientists believe that there is no evidence that we are being visited, watched, or invaded by intelligent beings from other worlds.

About 17 per cent of the brightest galaxies that have been ob­served are called elliptical galaxies. (An ellipse is like a stretched-out circle.) These galaxies contain mostly stars and seem to have little or no dust and gas.

Some galaxies are called irregular galaxies because they appear to have no special shape. These galaxies contain stars, dust, and gas. The two galaxies nearest the Milky Way are irregular galaxies.

There are also some small galaxies that are called dwarf galaxies. The smallest are only a few hundred light-years across and contain only a few thousand stars. There may be more dwarf galaxies in the universe than larger ones.

Galaxies are separated from one another by hundreds of thousands of light-years. They usually occur in groups or clusters containing from several tens to many thousands of galaxies.

The most distant clusters of galaxies so far observed lie billions of light-years from our Milky Way. And there are galaxies so far away. from us that it is almost impossible for us to imagine the vastness of the distance. So the answer to the question of how many galaxies there are in the universe will probably always remain a mystery.