Before 2005, we all knew that there was nine planets in the solar system. Then an asteroid named Ceres was discovered and shortly after Eris, an object on Pluto’s orbit, was discovered too. This prompted a rethink in the definition of a planet and Pluto was eliminated from the list on the account of having not cleared all the objects on its orbital path making the number of planets to be eight.

So, now our planets have 8 planets and 5 dwarf planets (where Pluto falls). Since then, scientists have discovered other planets outside our solar system – they revolve around a different star other than the sun. Of focus in this article are those which could be habitable. Of focus in this article though are those planets that could be able to sustain life.


For a planet to be habitable, the temperatures should be optimal to sustain life and for water to exist in its liquid state. If the planet is too cold, then the water on its surface will solidify. On the other hand, if it’s too hot, water will exist in its gaseous form or not exist at all.

The gases on its surface shouldn’t also be poisonous.

That is why in our solar system, no life can exist on Mercury and Venus for they are too hot due to their close proximity to the Sun, and from Jupiter all the way to Neptune. Actually, the reason life isn’t possible in Jupiter is the volatile nature of its atmosphere hence the name Stormy Planet.


Preliminary exploration reports by NASA and other scientists indicate the possibility of life in mass. NASA found evidence of water in Mars fuelling the belief that life could be possible in the second smallest planet. So much so that they are planning to have humans there by 2030, although Elon Musk-owned Space X has set their sights on 2024. The journey is estimated to take about 9 months.

Even then, there is the issue of Mars’ thin atmosphere, reduced sunlight and low gravitational pull that presents challenges on both landing and how life could thrive there.


Exoplanets are planets outside our solar system that revolve around a different start. You know the Sun is a star and there are many of them, right? It is estimated that there are more than 3000 planets outside our solar system.

In 2017, scientists discovered another star near our solar system and about 40 light years away from Earth called the TRAPPIST-1. It’s 0.08 smaller than the Sun, but the planets revolving around it are the size of the Earth.

Due to its comparatively small size, it the planets appear bigger than the star when viewed through a telescope. It also not as the Sun making it a possibility that life could indeed thrive on all its seven planets.

Do not get too excited since astronomers are still investigating the chemical composition of its atmosphere and the chance of liquid water on its surface. It could be a number of years before we even land a rocket in any of the exoplanets.