There is no scientific proof that aliens or other forms of intelligent life exist elsewhere in the universe, despite many purported UFO sightings around the world. Most astronomers believe that as technology increases, the likelihood of discovering aliens also increases.
Astronomers at the SETI Institute believe there are over 1 trillion planets in the Milky Way galaxy, in addition to planets elsewhere in the universe. Based on statistics, the probability that another planet has conditions suitable for life is high.
Advances in telescope technology, most notably the invention of the Kepler planet-hunting telescope, increase the likelihood of discovering planets similar to Earth. Data suggests that one out of every five stars has a planet suitable for life.