No one knows the exact number of galaxies in the universe, but it is estimated that there are more than 50 billion galaxies inthe universe!(How huge the universe is!!!)

The matter in the universe is so thinly dispersed that the universe can be compared with a building twenty miles long, twenty miles wide, and twenty miles high, containing only a single grain of sand.

While astronomers used to believe that galaxies were distributed more or less evenly through space, they have now found regions where galaxies are rare or absent. The largest of these regions is located in the direction of the constellation Bootes, and measures more than 300 million light years across.

A "light year" is a measure of distance, it is the distance that light travels in a year and is equal to about 9.5 trillion kilometres, or about 6 trillion miles.

About 25% of the universe consists of "dark matter", and about 70% consists of "dark energy", leaving only about 5% of the universe visible to us.

It is possible that many planets in the galaxy may not orbit around stars. Recent work by Kailash Sahu found six gravitational lenses in the star cluster M22 from objects smaller than brown dwarfs, the smallest type of star. Only one gravitational lensing event by a star was found in the same work.

Most scientists think that the universe began 13.7 billion years ago (that is 1,370 million years ago). But there is not much differece as other scientists say that the Universe is 10 to 20 billion years old.

According to the scientists our solar system was formed about 5 billion years ago.

The Earth was formed about 4.5 billion years ago.

Astronomers believe that the universe contains one atom for every 88 gallons of space.

At present the universe is believed to be at least 10 billion light-years in diameter.