The Earth is a big place . The U.S . space agency NASA says the Earth has a diameter of about 12,800 kilometers . And the organization Population Reference Bureau estimates that about 7.5 billion people live on our planet . That is a lot of people ! So , it can really come as a surprise when you see someone in a place where you do not expect to see them . This can make the world feel very small . For example , let's say I travel all the way to Brazil for a vacation . Then , at my hotel , who do I see ? I have traveled very far from home only to see someone I know from home ! That would be a great time to say : “Caty ! Fancy seeing you here ! What a small world !” It is always surprising to run into someone we know in a place as big as … the world ! We can say some form of “small world ” to show this surprise . Now , sometimes events and people are connected in a surprising way . In these situations , we can also say “small world .” For example , let's say you make a new friend . You two met while playing on the same sports team . You start talking about where your live and what you do . And as the two of you talk more , you both find out that you have the same English teacher ! You can say , “He's your teacher , too ? There are hundreds of English teachers . What are the odds ! It is such a small world !” These are all examples of coincidences . You were not expecting to find these connections between people , places , or events . And sometimes it is not always a pleasant surprise . Let's say I go to an art show in New York City . Now , on any given day there are probably many art shows taking place in the Big Apple . But the one I go to just happens to be showing the artwork of my former boyfriend . He's the artist ? Usually , we say “it's a small world ” to show surprise at a connection that seems unlikely , improbable , and against the odds . Generally speaking , “It's a small world ” means that sometimes the world can feel a lot smaller than it is . And that can be a good feeling . "It's a Small World " is also the name of a water-based boat ride at Walt Disney Company theme parks . And it is the name of the song you hear throughout the boat ride . The ride shows children from around the world in traditional costumes . They are dancing , playing , and singing . Sherman said Walt Disney wanted a simple song – one that could be performed in English and many other languages . He added that people everywhere share the same feelings . So , everyone should respect each other and love each other … after all !