• The Universe is seemingly infinite, both in terms of space and time. 
• Some estimates put the size of the Universe as 92 billion light-years in diameter. 
• The age of the Universe is calculated at 13.8 billion years.
• It has millions of galaxies and planets, thousands of them are confirmed and observed by us.

Early studies focused on water to determine if the planet can sustain life. Now they have finally realized that water is just one small indication of life, and exoplanets can have plenty of other forms of life, without H2O.

Similarly the definition of alien life can be an extraterrestrial being, or even bacteria. The earlier studies which only focused on earth-like planets and stable solar systems due to a better chance of finding habitable zones, have now broadened their vision.

Newer, bigger and better space telescopes are being launched by NASA and the European Space Agency to better understand the astro-biological life in the universe, and even our own galaxy.

The odds of advanced or intelligent life in the Milky Way is calculated by the Drake Equation, which puts the figure at 10,000 civilizations trying to communicate.

Various global agencies have been working to find intelligent life outside our solar system using telescopes, radio signals and other means, but the aliens are still eluding us for thousands of years.

The missing aliens have dampened the enthusiasm but the search continues.