Where are the Aliens?

by Esme Kelly

No one can really know if there are aliens or not, however the universe is so big, bigger than most of us can comprehend, so some scientists think it’s worth a look. To help narrow the search for these mysterious beings, scientists often try to figure out what aliens might be like and therefore what conditions they might require. For example, if we think aliens will be made mostly of carbon, like us, then we should look for planets that have carbon. If we think they will depend on liquid water, we should look for planets with liquid water.

Although none have been found yet, there are three exciting ways we might detect life beyond Earth in the coming years.

1. Probes to planets and moons - this involves sending probes to planets and moons in the Solar system. We already know there isn’t any other intelligent life in the Solar system, but there could be simpler life like microbes. You may have heard about the NASA missions to Mars – the latest is the Curiosity rover which has special equipment that might detect simple life like microbes on the red planet’s surface. 

2. Studying the atmospheres of other star systems - The second way we might detect life is by looking closely at the atmospheres of planets in other star systems, which are called exoplanets. Astronomers have detected lots of exoplanets, and recently found water in the atmosphere of one exoplanet but we still can’t tell if there is life on the surface. Excitingly, the next generation of optical telescopes will be able to detect gases in the atmospheres of nearby exoplanets. If we see that an exoplanet’s atmosphere has a mix of gases like Earth, that would be strong evidence that we are sharing the galaxy with other beings.

3. The search for extraterrestrial intelligence or ‘SETI’ - In SETI, we look for signals from space that look artificial or that don’t seem natural. Detecting an artificial signal would tell us that there was not only life, but life capable of producing advanced technology. SETI could detect an artificial signal from much, much further away than the other two methods; the disadvantage is that intelligent life is almost certainly rarer. We just don’t know yet how rare, and that’s the reason we need to look.

In conclusion the best explanation for why we haven’t found life beyond Earth yet is simply that we haven’t been looking hard and long enough, and our technology has not advanced enough, not because they’re not out there.