What might make life hard to recognize as life? By Caleb A. Scharf.

When you're trying to figure out what alien life might look like, it makes sense to be looking in the most extreme environments Earth has available. By Michelle Starr.

Arthur C. Clarke warned us to attempt no landings on Europa in 2010: Odyssey Two, the 1982 the science fiction novel , when the Earth mission returns to the Jupiter to explore beneath the ice of Europa, nine years after...

It’s a mighty big universe, but ET hunters are zeroing in on some prime candidates. By Andrew Masterson.

A look at the scientific evidence for panspermia. By Daniel Oberhaus.

Discovery has major implications for hunt for alien life on the red planet as it means any evidence is likely to be buried deep underground. By Ian Sample.

Meteorites might have delivered some of the basic building blocks, but there are still some missing pieces to the puzzle. By Elizabeth Tasker.

Will we ever salute Vulcans or cuddle tribbles? An astrobiologist explores the latest thinking on the forms alien life might really take. By Andrew Fazekas.

Deadly radiation could be breakfast for microbes on rogue planets, comets, and more. By Sarah Fecht.

Scientists have figured out how microbes can suck energy from rocks. Such lifeforms might be more widespread than anyone anticipated. By Emily Singer. (June 21, 2016)

Odd viruses flourish in boiling, acidic Yellowstone hot springs. By Joel Shurkin.

Scientists blast comet-like ice with radiation like that in space, creating a key building block for life.

Milton Wainwright believes he’s seen ET. In Earth’s upper atmosphere, he claims to have found evidence for panspermia—the hypothesis that life travels through the cosmos via meteoroids and other objects. A microbiologist and astrophysicist at the University of Sheffield, Wainwright sends large balloons up to the stratosphere, as high as 25 miles above the planet’s surface, to look for microorganisms drifting in from space. By Gayil Nalls.

Why life is constrained to be about the sizes we see on Earth. By Gregory Laughlin.

More than a mile below the surface, our planet supports diverse creatures that could give us clues about life across the solar system. By Sandeep Ravindran.

Earlier life-forms across the cosmos may have faced thousands to millions of times the cosmic ray dose that we do today. By Nola Taylor Redd. (Jan. 22)

European scientists have gathered tiny fungi that take shelter in Antarctic rocks and sent them to the International Space Station. After 18 months on board in conditions similar to those on Mars, more than 60% of their cells remained intact, with stable DNA...

Tardigrades, also known as water bears, are the ultimate survivors. They can handle everything from the vacuum of space to 600 times the normal atmospheric pressure. And new research is revealing how they manage one of their party tricks, turning to glass when there is not enough water to maintain normal life processes.

A small laptop-sized device is being developed at JPL to look for amino acids and fatty acids, with potential applications in space. By Elizabeth Landau.

In the search for extraterrestrial intelligence, some have been accused of harboring a sense of “carbon chauvinism,” expecting other life-forms in the universe to be made of the same biochemical building blocks as we are and tailoring our searches accordingly. Here are 10 examples of biological and nonbiological systems that stretch the definition of “life.”