An astronomy student from the University of British Columbia discovered new exoplanets in February 2020. Michelle Kunimoto was checking through data collected by NASA’s Kepler when she made the discovery. She came across a total of 17 exoplanets.


What are exoplanets?

Also referred to as Extra-Solar Planets, these are planets orbiting stars. These stars are at a fixed point, similar to our Sun’s position. Therefore, an extra-solar planet could be a planet within a different solar system from ours. From as early as the 16th century, astronomers have hinted at the likelihood of other solar systems. As such, there could be plenty of exoplanets out there waiting to get discovered. At the moment, there’s a list of more than 4000 exoplanets.


Ways of searching for exoplanets

When observed through powerful telescopes, stars appear as small dots. Planets are smaller than stars, making it even harder to spot them by merely looking for them. Therefore, scientists came up with indirect ways to help find these elusive planets. There are seven methods to search for exoplanets:


  1. The Transit Method –also called the Transit Photometry method, is one of the more common ways to hunt for exoplanets. Planets orbit stars. When a planet passes between its star and Earth, that’s known as a transit. When that occurs, the amount of light between the star and Earth dims a little, exposing its presence. If this happens regularly, then it’s an indication of a planet. The starlight may dim a little for smaller sized planets or a lot for more massive planets.


  1. The Radial Velocity Method – also called the Doppler spectroscopy, it was one of the first methods used to find exoplanets. That’s up until 2009 when the Kepler space telescope got launched. This method relies on the fact that stars orbited by planets do not stay stationary. The movement of the star is due to the gravitational pull of the surrounding planets. These movements cause a shift in the star’s colour signature. Shorter wavelengths have a more blue hue, while longer wavelengths will seem redder. Planet hunters watch the spectrum shift between blue and red. The more regular the shifts, the more likely a planet exists next to the star.


  1. The Astrometry Method – considered as one of the oldest methods to find planets, it’s been used since 1943. Stars with planets around them tend to move, though very slightly. Therefore, the Astrometry Method keeps track of a star’s movement relative to other stars within the area. However, it’s a slightly tricky method to use. As such, most of the exoplanet discoveries made have gotten classified as false positives.


  1. The Microlensing Method – happens to be the best method to find planets that are extremely far away. That’s because scientists can use it to look for planets thousands of lightyears away. It comes from Einstein’s General Theory of Relativity. Gravity from a star passing between another star and Earth causes the space near it to bend. That bend in the star’s light, makes it appear brighter than usual. The existence of a planet close to the lensing star turns that planet into yet another lens. That amplifies the brightness further.


  1. The Direct Imaging Method – a problematic method to use as it relies on a planet having unique characteristics. These include planets that were recently formed and are therefore still hot. Planets are always smaller than the stars they orbit. Thus, they quickly get lost in their star’s glare.


  1. Timing Variations – make a planet’s presence known due to the timing variations they cause to regular events such as natural radiation pulses and planetary transits. It’s the method that led to the discovery of Neptune in 1846. That was after scientists noticed that Uranus orbited the Sun either faster or slower.


  1. Phase Curves – relies on detectable brightness variations that come about due to the planet orbiting its star. A phase curve refers to the change in the brightness of a rotating object. The methods it can use to detect these variations include:
  • Using Reflection Signals based on the planet’s position from its star
  • Using Ellipsoidal Variations caused when massive planets change how their star appears from Earth
  • Using Relativistic Beaming when a star crosses the barycenter (the point where its gravity and that of the surrounding planet balances out) becoming either brighter or fainter


Significant discoveries during Michelle Kunimoto’s search

Among the exoplanets that Kunimoto came across was one Earth-sized world that could be habitable. That’s because it lies within the habitable zones, where it’s possible to come across liquid water. The planet has officially been named KIC-7340288 b. It’s one and a half times the size of Earth. It’s also believed to be a rocky rather than a gaseous planet. It could, therefore, bear a similar appearance to the bigger ones within the Solar System. Unfortunately, the planet is about 1000 lightyears away. That puts it exceptionally far away for exploratory visits. More data on the planet includes the fact that it has a year that probably spans 142 and a half days long.