There may be up to 2 trillion galaxies page 14 and more facts about galaxies A black hole could stretch you like spaghetti page 16 and other facts about black holes A huge cloud of water floats through space page 18 and other facts about the universe's oldest cloud There could be an infinite number of universes page 20 and other facts about the multiverse theory
We might have found aliens without realizing page 22 and other facts about alien life 95 of the universe is missing page 24 and other facts about dark matter Even More Facts page 26 Glossary page 28 Further Information page 31 Index page 32
1 FACT NEW PLANETS ARE DISCOVERED ALMOST EVERY DAY Back in 1994 scientists Michel Mayor and Didier Queloz found a planet outside our solar system but people didn't believe them for almost a year Now we have found thousands with more discovered all the time Exoplanets An exoplanet is what we call a planet outside our solar system Exoplanets circle around other stars just as Earth circles around the sun Although no exoplanets were found until the 1990s scientists had believed for years before this time that they existed The reason behind this belief was that in understanding how planets formed around our sun scientists realized that planets would similarly form around other sun like stars
An artist's impression of 51 Pegasi b circling a star Too big So if scientists believed in exoplanets why did it take them so long to be convinced by the two scientists 1994 discovery Well the issue was that this planet named 51 Pegasi b the first ever found circling around a sun like star was just too big The existence of an exoplanet this size didn't fit with scientists ideas at the time about how planets were formed so they thought at first that it must be a mistake I'm looking for a Goldilocks planet Goldilocks planets The powerful telescopes available today help with spotting exoplanets One focus of this search is finding Goldilocks planets named after the fairy tale Like Goldilocks searching through the bears house scientists are trying to find a planet that is not too hot not too cold but just right for life to exist there Not the first 51 Pegasi b was the first exoplanet to be discovered orbiting a sun like star but it was not the first exoplanet to be discovered In 1992 Aleksander Wolszczan and Dale Frail found exoplanets around a type of tiny fast spinning star called a pulsar which is the squeezed core left over after a massive star explodes FACT 2 The first evidence of an exoplanet was noted in 1917 but it was not recognized as a planet at the time
