Earth has been able to accommodate humans for thousands of years because natural resources that support life are plentiful. We have had the essentials for living – most notably air, water and minerals. Add the sun's energy and you have an ideal environment for the human race.

However, scientists tell us that in about two billion years or so, as the sun approaches its expiration date, our star will expand in size and increase its energy emission rate in such a way that oceans will boil and the environment will be unsustainable for human life.

In the meantime, we must keep in mind the possibility that a thousand-mile-wide asteroid could hit Earth. It has been estimated that such a life-ending event could happen at a rate of about one every 300,000 years. While it is true that several agencies and groups around the world are on the lookout for Near Earth Objects (NEO) such as large asteroids that may cross our planet's path, there is little we can do to divert one of these huge rocks.

Of course, there is the ongoing threat of total nuclear war which would last only an hour or so, but could eliminate most life on Earth. Fortunately, the horrific thought of this threat has acted as a deterrent to such wars for the last 75 years. We can only hope that it stays that way.

Even if Earth survives these various threats, the human race is consuming our natural resources at a rapid rate and we do not even have a solution to the effective disposal of waste products. As the world population continues to grow and resources become scarcer the pressure to leave our home planet will increase dramatically. However, leaving Earth is only part of the challenge for human survival.

We will need at least one destination and a transportation system to get there. Space colonies in orbit about the Earth will not be sufficient. What we need is what we have on Earth. So, we must find another planet with the natural resources and a sun that can provide the energy to sustain life. Thus, we need to find at least one "exoplanet" – an Earth-like planet beyond our own solar system. The good news is that NASA has used the Kepler Space Telescope to find thousands of potential exoplanets over the past two decades.

As it turns out, exoplanets come in a huge variety of sizes and orbits. However, planet searchers are looking for a special kind of planet that is roughly the size of Earth and is orbiting a sun-like star at an acceptable distance for life support.

A suitable distance is one that at least allows the planet's temperature to sustain liquid water oceans. Of course, an acceptable situation is one that offers simple thermal equilibrium and the greenhouse effect of the planet's atmosphere.

In 2016, astronomers announced the discovery of a potentially suitable planet that is orbiting Proxima Centauri. This star is also known as Alpha Centauri C, a red dwarf that is small and has a low mass. It is about 4.2 light-years from our sun in the constellation of Centaurus. This potential exoplanet is known as Proxima b and is about 1.3 times more massive than Earth.

Assuming we have found a suitable new home, the next challenge is getting there. If we could travel at the speed of light it would take over four years to get there. However, the laws of physics tell us that we cannot travel that fast.

Available technologies indicate it would take several generations to reach this destination. If we had an interstellar transportation device the humans that depart Earth would not be the humans that arrive at the exoplanet.

The people that arrive would have been born and raised on a spaceship, never having experienced Earth. Communications from Earth will require more than four years to reach the new planet and vice versa. It seems clear that Earth humans and exo-humans will have few cultural attributes in common.

If the human race is going to survive, we must seriously consider interstellar travel.