Life began on the Earth around 3.5 billion years ago. Has the same thing happened somewhere else in the universe? On an icy moon? On a planet in the Goldilocks zone of a distant star? Imagine if hypothetical aliens were looking for signs of life in our solar system. How might they investigate us from so far away?How to Find a Living Planet, Ocean Moon, Ocean World: The water beneath Europa’s icy surface, and The Top 5 Places to Look for Alien Life.