Title: 
Headings: How Many Worlds Are There?
Wonder of the Day #1235
How Many Worlds Are There?
Have You Ever Wondered...
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Content: And the Milky Way is just one galaxy in our universe. Scientists estimate that there are hundreds of billions of galaxies throughout our universe. When you think about them, the numbers are staggering, and scientists believe the possibilities are endless. More and more, scientists are beginning to believe that we are not alone. Of course, there is no proof that life exists elsewhere, but experts are learning more every day about the probabilities that it might. Scientists believe that Earth is the only planet in our solar system that supports life, at least as we know it on Earth. For human beings to live and thrive, conditions have to be “just right," like they are on Earth. For example, humans could never survive the overwhelming heat on Mercury or the frigid cold on Neptune. Other conditions, such as poisonous gases and lack of water, also prevent other planets from being good hosts for life. Armed with this knowledge, scientists have long believed that life might be found elsewhere in the universe on planets similar to Earth orbiting other stars.