WHAT ARE EXOPLANETS?
In our Solar System, the planets all orbit around the Sun, which is a star. An exoplanet is a planet that is outside of the Solar System and orbits around a different star. It is predicted that there is at least one exoplanet goes around every star in our galaxy.
Astronomers are people who study the universe and how it works. In 1995, two astronomers, Michel Mayor and Didier Queloz, were the first people to discover an exoplanet. They were awarded the Nobel Prize in Physics for this discovery. Since, thousands more have been discovered.
HOW DO WE FIND THEM?
It is often very difficult to see exoplanets with telescopes. This is because they may be very far away or hidden by the brightness of the stars that they orbit. Sometimes, it is possible to see them in this way, if the bright light of these stars is removed. However, astronomers have come up with other ways to find these planets. There are three main ones:
- The wobble method
When a planet goes around a star, there is a force that pulls the star towards the planet. When the planet pulls on the star, it causes it to wobble. This makes it look like the star itself is circling around a point in space. Astronomers know that if a star moves in this way, then there is a planet around it. However, this method only works for very large planets as they are able to exert the greatest pulling force.
- The transit method
A transit occurs when the orbit of the planet causes it to move in front of its star. When this transit occurs, the planet blocks out some of its light. Astronomers can see that the star is dimmer and detect the planet.
By looking at how much the brightness decreases, astronomers can figure out the size of the planet. By looking at the time between transits, scientists can figure out how long the planet takes to orbit the star.
- Gravitational microlensing
This method uses the fact that light from distant stars can be detected from the Earth. Sometimes, the path of this light will be bent if an exoplanet passes near it. This is because of the gravitational pull of the exoplanet. Astronomers can detect this bending in order to find the exoplanet.
WHY IS THIS IMPORTANT?
We are still looking for a planet that has similar features with Earth. These include size, temperature and water. These conditions allowed life to form on Earth so astronomers are hopeful that they have allowed life to form on Earth. The more exoplanets we find, the more likely we are to find new forms of life in space!