If you want to believe, now is the time: the hope that we might one day stumble upon alien life is greater than it ever was. No, it’s not going to be little green men speeding through space in flying disks—more likely microbes or primitive bacteria. But a discovery like that would nevertheless be a sign that we are not alone in the universe that life elsewhere is a possibility.

Where are we going to find that life? It was once thought the solar system was probably a barren wasteland apart from Earth. Rocky neighbors were too dry and cold like Mars, or too hot and hellish like Venus. The other planets were gas giants, and life on those worlds or their satellite moons was basically inconceivable. Earth seemed to be a miracle of a miracle.

But life isn’t that simple. We now know that life on Earth is able to thrive in even the harshest, most brutal environments, in super cold and super dry conditions, depths of unimaginable pressures, and without the need to use sunlight as a source of energy. At the same time, our cursory understanding of these obscure worlds has expanded tremendously. Our rocky neighbors of Venus and Mars may have once been temperate and Earth-like, and some of the life might have lingered on after these planets’ climates took a turn for the worse. Several of the icy moons that hang around Jupiter and Saturn might have underground oceans that could sustain life. A couple may even have atmospheres. And still other places that seem to be too exotic for life continue to surprise us.