There is no definitive answer as to whether other universes exist, although many astronomers believe it is highly likely and have several theories on how or where they exist. Some people theorize that an infinite number ... More » Science Astronomy Universe

According to NASA, more than 1,700 planets have been confirmed outside of our own solar system. However, the number of planets in the universe could essentially be infinite because scientists have yet to find the so call... More »

The exact number of stars in the universe is not known, and the total figure might be unknowable from the Earth's position in space. The universe almost certainly contains no fewer than 10^24, or 1 septillion, stars, and... More » Science Astronomy Stellar Astronomy

The belief of early astronomers that the Earth was the center of the universe stemmed from limited astronomical tools and geocentric attitudes. The Ptolemaic Model, developed around 100 A.D., presented the Earth-centered... More »

The exact number of solar systems is not known. According to NASA, there are more than 100 billion galaxies within the universe. One of these galaxies is the Milky Way galaxy, where our solar system is located. More »

There are billions of stars, and no one knows how many solar systems there are. The Earth's galaxy, the Milky Way, is so large that it would take an object 100,000 years to cross it traveling at the speed of light. More »

Galileo Galilei is famous for his physics-related and astronomy-related observations. He built his own telescope in 1609 and used it to study the cosmos, eventually concluding that Earth’s solar system is heliocentric. G... More » Science Astronomy Universe