As of 2014, there is no single piece of concrete evidence to prove the existence of alien life, although most scientists today agree that the potential of discovering life outside Earth is much greater than previously thought. According to Discovery News, alien life is considered highly probable and will likely be discovered by the year 2024.Know More
Fictional accounts of aliens found in mainstream media aren't considered an accurate representation of alien life. Some scientists believe that aliens will be simple life forms such as bacteria or single celled organisms while others believe that more complex forms of life exist. Within the Milky Way galaxy, there are several planets that may be able to support some type of life.
NBC News has stated that over half of the galaxies visible from Earth's telescopes may have planets and solar systems similar to our own. Scientists often determine the probability of alien life by examining the availability of water on other planets. Currently, there are several planets that are thought to have some form of water available, including Mars and Titan, one of Saturn's moons.
The debate of whether alien life exists is hinged on the lack of definite proof of other species outside Earth. According to New Scientist, there are some examples that point to irrefutable evidence. For example, methane has been found on Mars. The presence of methane is linked to the metabolic process that occurs when life forms process organic compounds for energy. This evidence is controversial and has only been accepted as proof of alien life by a portion of scientists.Learn more about Astronomy
Copernicus discovered that the planets revolved around the sun, rather than around the Earth. Called the heliocentric model of the solar system, the concept was at odds with the conventional wisdom of the time, which held that all heavenly bodies rotated around the Earth.Full Answer >
Gravity is one of the fundamental forces of the universe, and it keeps us on Earth because it is relentlessly attractive. Every massive particle exhibits gravity by pulling closer to every other particle. The strength of this interaction is dependent on two quantities: the amount of mass and the distance between objects. It is possible to escape Earth's gravity if you have enough energy to speed up sufficiently.Full Answer >
As of 2015, there are 1,071 active, man-made satellites in orbit around Earth alone. In addition, there are two man-made satellites orbiting the moon; one each orbiting Mercury and Venus; three orbiting Mars; one orbiting Saturn; one orbiting Jupiter; one orbiting the asteroid Vesta; and four orbiting the sun.Full Answer >
The geocentric theory, or the Ptolemaic system, was one of the earliest theories regarding the origins of the universe, and it posited that the sun, stars and even the other planets revolve around the Earth. Ptolemy was not the first to suggest this theory, though, as documents indicate that Aristotle and Plato discussed this paradigm.Full Answer >