Ever since we looked up to the stars, us humans have never stopped questioning whether other life exists beyond Earth. Are we alone in this universe? Or are there other creatures, maybe even ones that look like us, out there somewhere? Today, we’ll explore the fascinating possibility of extraterrestrial life (the scientific term for aliens) in our own Solar System.

How does life form, anyways? 

Life is beautiful and complex. But how did it suddenly come about? Let’s turn the clock back and look at our early Earth to find out. Around four billion years ago the Earth stopped getting hit so much by meteorites, so it began to cool down. When the temperature dropped, clouds formed and released a lot of rain - so much that oceans formed. With the combination of this ocean water, energy from the sun, and soil rich in certain chemicals, life slowly emerged. At first it was only tiny, single celled organisms. But then, over billions of years, these organisms evolved into all the diverse creatures present on Earth today. So, in order for life to form as we know it, there needs to be enough water, certain elements (like carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur), and a plentiful amount of energy.   

Where else could life be in the solar system? 

Now, let’s explore the solar system to see if life could form anywhere else. Today we’ll explore two worlds, Mars and Europa. Our first destination is Mars.  

 Mars 

The red, rocky planet of Mars has captured the imaginations of mankind for hundreds of years. Countless stories have been written about Martians, or intelligent aliens that live on Mars. But, it’s not just writers and artists who have imagined Mars as having life - scientists think it’s very possible that life may have once existed here. Around four billion years ago, there were probably oceans of water on Mars, just like on Earth today. During this time, Mars had active volcanoes and a much warmer atmosphere, so it is very possible that life could have formed just the way it did on Earth. Sadly, Mars eventually lost all its oceans and dried up into the barren, rocky planet we see today.  However, there still could be life hiding somewhere, or at least fossils of creatures that once live. In fact, this July, NASA sent a new rover, called Perseverance, to Mars. Its mission is to try and find evidence of life, and it will arrive in about four months. Maybe we will discover that
Martians exist after all...

Europa 

Next stop, Europa, the sixth out of Jupiter’s seventy-nine moons. Hidden beneath its scarred surface, there is most likely a giant saltwater ocean that surrounds the entire planet. Galileo, a spacecraft which flew by Europa twenty years ago, helped prove this when it detected giant sprays of water from its surface.  Like Earth, Europa’s ocean might even host life. How can this be, though? Europa is millions of miles away from the sun, so if there was life, how could it get enough energy to survive? Well, even in the deepest oceans of Earth, where there is no sunlight, we have discovered creatures called extremophiles which get all the energy they need from chemicals spewing out of the ocean floor. If the ocean floor of Europa is like Earth’s, there could be creatures living there. In 2024, NASA actually plans to launch a spacecraft, called the Europa Clipper, to fly near this exciting planet and get valuable information about it’s hidden ocean.  

This concludes part one of our exploration for life in the Solar System. In the next part, we will discuss four more worlds, Ganymede, Callisto, Enceladus, and Titan, all of which may have amazing secrets hidden beneath their surfaces…