This is of course a hotly debated topic in the scientific, astronomy and science fiction community alike.

Commenter DM poses an interesting question:

I’ve always wondered, if there is bacteria on mars, wouldn’t that mean there’s a possibility of some of that bacteria preiviously evolving into life, that became a civilization like our own but that either fell by other life forms or destroyed themselfs like we have a high chance of doing eventouly. They could have also left their planet because the did not think it was suitable for life anymore, or that they knew of our existence and desided to leave and allow our species and civilization to grow. And if they were attacked or even just left they could come back and check on our growth as a species which would explain UFO’s

Commenter SG had this to say in reply:

Sounds possible yes, but very long ago (I forget when I learned about this last year lol) Mars was much like Earth, with oceans, possibly trees, etc. But due to its much smaller size and farther distance from the sun, it was not able to retain it’s heat for ever, much like the water in a bath will gradually drop temperature more and more and more, and the less hot water in the bath, the less time it will take for it to cool off. Losing enough heat caused Mars’ core to freeze. And since it is the core that creates the protective magnetic field that protects the planet from the harsh radiation of the sun, with it being frozen, there was nothing to protect the surface from the relentless strikes of the solar winds. Over time, all of Mars’ water and/or vegetation was destroyed or evaporated into space, leaving behind what we see Mars as now. Earth will, too one day cool off and become much like Mars, but since its much bigger and closer to the sun I hope that won’t be for a few billion years. 🙂

^Not for sure if this is all correct, we had a unit on space in science last year, and we talked about this.

We hope you like the video and were intrigued by these observations!