Become an Expert: Exoplanets

Exoplanets, planets that orbit stars other than our sun. They’re one of my favourite topics in general astronomy. But how did they first get detected, what is the future of them and why does it matter? These are the questions I’ll be answering today so you become an expert on exoplanets!

So the first exoplanets were detected by astronomers detecting a wobble of a star at regular integers. This wobble occurs because of the exoplanet in question’s gravitational pull on the star. It isn’t much but we can detect it. You may be familiar with this process because of one of the two Nobel physics prizes (2019) was for the discovery of the first exoplanets using this method. 

However, today we use the transit method. This is when an exoplanet transits across the star and blocks some of the light. We detect this by continuously observing a star and look for a slight decrease of light. This decrease in light could just be <1% depending on the star but with powerful telescopes, we can detect this. Nasa sent a space mission into the orbit of the Earth, called Kepler, to find exoplanets using this method. It recently decommissioned Kelper, but ESA has sent a space mission up as a successor of Kepler to find more exoplanets called TESS. TESS additionally will be able to study the atmospheres of some exoplanets by looking at the light given off from them. That information will be sent back to Earth so astronomers can study the colours to find what the main chemicals are in the atmosphere by studying what colours different gasses glow.

So what’s the future? Will we visit them? How will we find out more information about these planets? Well in the near future we are trying to detect exomoons. These are moons that orbit around exoplanets. We detect these by using the transit method for planets and try and predict when the planet should transit as accurate as possible. We then look for the planet’s transit to be slightly earlier or later. If we detect this then we know that most likely we would have found an exomoon. We have detected one exomoon but it isn’t confirmed. The media, as they usually do, bent the truth and said that the first exomoon was 100% detected and confirmed when in fact, it is still in its conformity stage now (October 2019). 

In the further future, we probably won’t see humans going to these otherworldly bodies, as the closest one (Proxima b) is more than 4 light-years away, meaning that it would take over 4 years to get to the planet if we travel at light speed. Never fear though, there are plans to send a spacecraft with nano-like sub space crafts to explore the Proxima system. These plans are still in the planning stage and if everything goes to plan (which it won’t! Look at the Webb telescope, it was supposed to be launched in 2000 but is still in development) we’re looking at the late 2030s. Although it is a nice thought. Not much more information can be gathered from Earth, other than exomoons and their atmospheres. So to really understand these worlds we need to send spacecraft there.

So why do we do this? Why do we need to understand exoplanets? It’s because it is human nature to wonder and discover. Why venture over that hill? Why climb the tallest mountain? Why cross the largest seas? It is what we have done, what we are doing and what we will do. It is our job as humans to study the universe and our world for then we can have a greater understanding and we can fulfil our name as homosapiens or wise man.

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