From extraterrestrial beings to UFOs, there's countless theories and reported sightings of life from other galaxies. Whether you believe in Grays or are simply interested in learning more, below are some stories that might spark your interest. You can check out these otherworldly programs here or on the PBS app.

From the invading aliens of ‘War of the Worlds’ to post-world war escapism literature and even real-life scientific exploration today, the stories of Martians have changed throughout time. Find out how we’ve gone from viewing Mars as a pre-existing utopia populated by alien races to actually seeing the planet as a potential new home for earthlings.

Our solar system is a tiny bubble of habitability suspended in a vast universe that mostly wants to kill us. In fact, a good fraction of our own galaxy turns out to be utterly uninhabitable, even for suns — like stellar systems. Is this why most of us haven’t seen aliens?

Half of the universe is filled with expansionist alien civilizations, and it’s only a matter of time before they’ll reach us. OK, that sounded a little sensationalist. But it’s also the conclusion of one astrophysics paper. Let’s see how they figure this, and whether we should take it seriously.

On our search for alien lifeforms we scan for primitive biosignatures, and wait and hope for their signals to happen by the Earth. But that may not be the best way. Any energy-hungry civilization more advanced than our own may leave an indisputable technological mark on the galaxy. And yes, we’re very actively searching for those also. Time to update you on the hunt for galactic empires.

Ultra-sensitive telescopes have transformed alien planet-hunting from science fiction into enthralling hard fact. Join NOVA on a visit to exotic worlds orbiting distant suns to answer an age-old question with thrilling new science: are we alone?

This is the craziest proposal for an astrophysics mission that has a good chance of actually happening. A train of spacecraft sailing the sun’s light to a magical point out there in space where the Sun’s own gravity turns it into a gigantic lens. What could such a solar-system-sized telescope do? Pretty much anything. But definitely map the surfaces of alien worlds.

There’s one rule on Space Time: It’s never Aliens. But every rule has an exception and this rule is no exception because: It’s never aliens, until it is. So is it aliens yet? On this Space Time we’re going to examine all the best case scenarios for life beyond Earth.

Grey Aliens, sometimes called Zeta Reticulans, Roswell Greys, or just Grays, are defined by their humanoid forms, long limbs, large black eyes, small noses, thin mouths, and of course, gray skin or gray clothing. They are some of pop culture’s most recognizable representations of extraterrestrial life. But where did this depiction of extraterrestrials come from?

Mixing a fictional narrative with documentary interviews, "First Contact: An Alien Encounter" tells the dramatic story of an encounter with an extraterrestrial artifact and explores the new tools we have available in the search for life beyond earth. 

In early quarantine, a Pakistani couple in northern Virginia bicker and ruminate about extraterrestrial and terrestrial border-crossings of multiple kinds, after spotting what they believe is a UFO outside their home. 'There Was Nobody Here We Knew' is as much about finding answers as it is about looking inward to understand how we arrived at where we are and where we are headed.