You may have seen the movie Contact, adapted from Carl Sagan's book in which a young female scientist receives a radio transmission from the star system "Vega" and the struggles of proving her extraterrestrial contact and being a female in her field go on from there.

Unfortunately Jodie Foster receiving an alien transmission will probably not be the way we find other life in our universe.

SETI is a privately funded group of astronomers still listening for radio signals to this day from intelligent lifeforms, but this may or may not turn up any good news. It is extremely unlikely that if any intelligent life forms are close enough to reach with a radio transmission, that they would even be able to retrieve the transmission because of the inverse square law. All of our radio signals have become indistinguishable only a few light years away from Earth.

We keep listening just in case they're advanced enough to send signals to us that don't degrade over long distances.

Lucky for us, the real science of searching for life is much more promising than that

Exoplanets

The most promising efforts are that of the exoplanet search performed by the Kepler mission:

It's a mission searching for habitable planets that may host life. It will also explore the diversity of other types of planets, allow us to map different solar systems in the Milky Way, and determining how long it would take to travel to these promising planets. So far Kepler has discovered 3,000 possible exoplanets since its launch in March, 2009. 

The gas giants are much easier to find because the telescope can pick up on their orbit which has a 10% probability of detection, but earth-sized planets in the habitable zone is about a .5% chance of seeing it, because we have to catch the planet in orbit at just the right time when it's orbiting in front of its sun, facing us.

This probability of the orbit being aligned is equal to the diameter of the star divided by the diameter of the orbit. 

Kepler will detect planets in from of a sun in order to measure the planet's diameter while scientists are able to measure the Doppler effect of the star in order to measure the planets mass.

What is the Doppler effect?

If you've heard an ambulance drive past you, do you remember the change in pitch as it passed you? It became higher closest to you then lower as it departed.

This effect that any type of waves have on an observer is the same way we detect exoplanets. Planets produce the same effect when orbiting its sun, the sun will actually wobble and scientists calculate this wobble with extreme precision to determine the planet's mass, which will determine its classification of being a gas or solid rocky planet.

Well we certainly know there isn't any "intelligent" life within our own solar system besides us. But we are currently searching for evidence that any life forms either exist today or once existed when the other planets were more habitable in their past.

Prospecting Mars

We send rovers to mars to study the planets history, geology, structure, and atmosphere.

Scientists have discovered salty water deposits as well as geographical evidence that Mars was once a warm and liquid water covered planet.

With a future mission to send humans to Mars, this will actually confirm the answer to our questions about this possibility.

Prospecting Europa
Jupiter's moon Europa has a surface made up of ice, however due to tidal flexing from Jupiter's gravity has caused Europa to heat up under it's surface caused by friction. Recent discoveries proving this hypothesis to be true is we've been able to observe water reaching to the top of the surface. This means if we send a robot to explore Europa, it probably won't have to drill through miles of its solid icy surface. It also has a small atmosphere consisting mainly of oxygen. Europa is a great prospect for extraterrestrial life elsewhere in our solar system.

There are several other places in our solar system to look for life's precursors for instance scientists have spotted them on Titan and discovered that Mercury may have also contained liquid water in its early life. There will probably be a mission to visit Europa in the future.

Why look for life on other planets?
Even proof that single celled organisms live elsewhere in our solar system would be able to get us astronomically closer to understanding our own origins. Discovering other advanced intelligent life would change our place in the universe significantly.

Considering there are 100 billion galaxies in the universe that we can know about and about 100 billion stars inside of each galaxy that may contain millions of diverse planets and some of those planets might be small enough and a certain distance from its sun that creates habitable temperatures and perhaps those thousands of possible habitable planets had asteroids hit them containing life's building blocks and those organisms adapted and evolved into something greater over millions of years, means there's a great possibility of life on other planets. Finding the little organisms is the first step in identifying ourselves and our place in the universe.