Astro2110 – The Solar System - Potentially Hospitable Exoplanets – UNIVERSE

One of the most exciting thoughts for many is the possibility of life on another planet. With our Solar System being explored without success, the search has spread to other systems for a hospitable exoplanet. An exoplanet, also know as an extrasolar planet, is simply a planet outside of our solar system. The goal for many has been to hopefully discover a planet with the capabilities of supporting life, either some of its own or some of ours. But what are scientists and astronomers looking for in order to deem a planet potentially hospitable?

§  It must be in the circumstellar hospitable zone (CHZ). 

§  The CHZ, also known as the Goldilocks Zone, is the area around a star where the temperatures and pressures of an orbiting planet would allow for liquid water. If the planet is too close to the star, the temperatures will be too high and water, if it exists on the planet, will do so only as vapor. If the planet is too far away, water can only exist as ice. 

• It must have water.
• It doesn’t have to have oceans of water, but there must be some kind present. This can be determined by searching for various atmospheric elements to ensure some water is still on the planet.
• Radiation is at a minimum.
• Many exoplanets orbit red dwarf starts, which are known for their frequent and harsh solar flares. If the star is experiencing flares that reach out far enough, radiation could reach the planet and threaten life.
• Nitrogen and Oxygen.
• While oxygen wouldn’t necessarily mean life, it would be damn near impossible for life to exist without it. Complex life would also almost certainly require amino acids, which would need nitrogen to be constructed.

Currently there are no systems that can detect for all of these, but it is what would be needed to roughly determine if life would be at all possible to be sustained on an exoplanet. Think of it like baking a cake: you need a list of ingredients, added in a certain way, and baked in a specific way. You may have all of the main ingredients but if they’re in the wrong quantity or you’re missing the tertiary ingredients your cake isn’t going to turn out very edible. Our list is a partial recipe for a hospitable planet, that with the right other elements and right setting could support life.

National Geographic link discussing this topic.

Source: https://my.vanderbilt.edu/astro201solarsys/page/48/