Exoplanets are planets that are located in other solar systems, in which it might be possible to have human colonies in the future. Interstellar travel, however, is time consuming and very challenging, and we do not yet possess the technology required for it. If the humankind manages to colonise the Solar System, the next step might be the exoplanets.
Search for exoplanets
So far, scientists have managed to identify around 2 000 exoplanets. Because our methods of discovering exoplanets are still quite limited, most of the found exoplanets are huge gas giants. However, the scientists have also managed to locate smaller planets, the smallest having just two times the mass of the moon.
In the whole galaxy, there are approximately hundred billion exoplanets, of which billions are in the habitable zone of their stars. This is an incredibly large number, and it is very possible, that many of these planets would resemble the Earth almost in every way. Its possible that many exoplanets could already harbour life. In a way, colonizing exoplanets might be easier than trying to terraform planets in our Solar System.
Distances and transport
The biggest problem with the exoplanets is the distance between solar systems. The closes exoplanet we are aware of, and which also could be habitable, is Tau Ceti e, which is located over 12 light years away from the Earth. The closest exoplanets that are even more Earth-like are located hundreds of light years away. Therefore, traveling there requires completely new spacecraft technologies.
Spacecraft could be built to resemble large space habitats, which could survive independently for hundreds of years. These space stations, sailing through the space, could explore different exoplanets, before deciding which planet they would colonize. Spacecraft could also work independently, while the humans would be asleep on the craft.
When traveling vast distances with high speeds, time dilation should also be considered. The closer the ship travels to light speed, the shorter the time experienced for the passengers onboard. If we would be able to travel at near the speed of the light, a trip of thousands of light years might feel like a couple of minutes for the passengers. However, time would pass on Earth on a normal speed, so they could never return to their loved ones.
At the moment, we do not have the technology to reach high speeds. Building a space habitat could be possible, but this would require huge amount of development, before humans could be sent to other solar systems. Therefore, the best option for now is to concentrate on colonising our own Solar System.
Exoplanets might be colonised in the future. Our Sun is going to shut down at a distant point in the future, so other planets and systems should be colonised in order to ensure the survival of mankind. Technology, however, is still insufficient, but we will see what the future will bring us.