The Hunt for Alien Life on Exoplanets May be Harder Than Previously Thought

It turns out that finding life on other planets may be far more of a challenge than scientists once thought. A new study reveals the difficulties of searching for life outside of our solar system.

When searching for life on other planets, researchers normally concentrate on suitable conditions that could support it. More specifically, they look for the presence of multiple chemicals such as methane and oxygen in an exoplanet's atmosphere. This mixture is considered an example of a biosignature, or evidence of past or present life.

Yet it seems as if the method to detect biosignatures may actually produce a false positive result. In fact, the researchers found that a lifeless planet with a lifeless moon can mimic the same results as a planet with a biosignature.

"You wouldn't be able to distinguish between them because they are so far away that you would see both in one spectrum," said Hanno Rein, one of the researchers, in a news release. He continued by explaining that it would be impossible to obtain a genuine biosignature from a false positive, "A telescope would need to be unrealistically large, something one hundred meters in size and it would have to be built in space. This telescope does not exist, and there are no plans to build one any time soon."

There are currently 1,774 confirmed exoplanets that are known to exist. Yet there could be as many as 100 billion in the Milky Way Galaxy alone. While the new research shows that it will be hard to detect alien life, it's not impossible.

"We should make sure we are looking at the right objects," said Rein in a news release. "As for exoplanets, we want to broaden the search and study planets around stars that are cooler and fainter than our own sun. One example is the recently discovered planet Kepler-186f, which is orbiting an M-dwarf star."

The findings are published in the journal Proceedings of the National Academy of Sciences.