Learn 10 amazing facts about our world in part 7 of this series.

Here are 10 amazing facts about our world:

Number 10 - Library of Congress in Washington D.C., is the largest library in the world and has nearly 151.8 million items on 838 miles of bookshelves.

Number 9 - The pupils of our eyes can dilate just by sound. The smallest noise causes our pupils to become larger and make vision slightly blurry.

Number 8 - On average a person spends nearly 6 years dreaming during sleep.

Number 7 - Every day the heart pumps approximately 2,500 gallons of blood.

Number 6 - According to Animal Planet an octopus does not have a backbone allowing it to escape from holes and cracks as small as a dollar coin.

Number 5 - When you are snoring, you can't dream.

Number 4 - A cat has a total of 64 muscles in both its ears - 32 in each ear.

Number 3 - Condom sales are usually 20%-30% higher around Valentine's Day according to Durex.

Number 2 - In ancient Egypt, the symbol of a woman's status was the color of her nails, red representing the highest rank.

Number 1 - Dolphins keep half of their brain awake while the other half sleeps. This sleep behavior helps them guard against predators.