Question: How do scientists discover exoplanets outside of the solar system without physically being in space?

What are Exoplanets?

Exoplanets are planets that orbit stars beyond our Solar System. 

For many decades, scientists have been able to discover new planets outside of our Solar System. Technological advances in the workforce have increased findings to uncover unknown planets in space, and in other terms these are known as “exoplanets.”

The first exoplanet breakthrough was discovered in 1995 – when scientists found a planet in orbit around another star. Within 20 years, we have discovered more than 3,500 exoplanets beyond our Solar System. According to certain sources, there is more than one exoplanet for every star, which indicates that there are more exoplanets in the Milky Way than there are stars. Until 20 years ago, scientists assumed that they could only study planets that were found within the Solar System. Their main assumption was that other planets were beyond the Milky Way, but none were discovered and Scientists didn’t have the rights tools or methods to find them. Today in science, we know that there more than thousands of planets orbiting around other stars. They come in many different shapes and sizes, with different types of matter and chemicals. Some can be smaller than Earth, and bigger than planet Jupiter. Many exoplanets can be found around individual stars or in multiples systems. In the star systems, there can be singular or multiple planets orbiting around the star. 

Exoplanets are being discovered by scientists every day… but how are they finding them so easily, and what are their methods to finding these planets beyond our Solar System without being above earth, and in space? 

Scientists use a list of methods to find Exoplanets beyond our Milky Way. The most common methods used in the workforce are: The Transit Method, The Wobble Method, Direct Imaging, and Microlensing.

The Transit Method:

A solar eclipse is a type of transit. This occurs as the moon passes between the Sun and Earth. The Exoplanet Transits occurs when a distant planet passes between it’s Star and Earth. When a solar eclipse happens, the sun’s light goes from 100% to 0% as seen from people on earth, and goes back to 100% when the eclipse is over. When scientists observe distant stars in order to find transiting exoplanets, a star’s light might potentially dim by very little amounts or even smaller fractions of that size. The minute that the star is dim, it’s light can reveal a hidden planet. The dip in a star’s light is resourceful for uncovering exoplanets. To use this method, scientists/astronomers are required to develop sensitive instruments that can quantify the light shining from the star. Even when they looked for unknown planets for several decades, they couldn’t find any signs or evidence until the 1990’s. 

The Wobble Method (Also known as the radial velocity method): 

In all gravitational-bound systems that include stars, objects in orbit (a star and exoplanet) move around a known center of mass. When an exoplanet’s mass is significant to the star’s mass, there is a possibility for scientists to notice a wobble in the center. It would be detected by a shift in the star’s light frequencies. This shift is known as a Doppler shift. It has the same effect of a race car that makes the sound of a vroom – high-pitched coming towards you, and low-pitched when the car races away. When astronomers measure cyclic changes within the light spectrum of the star, they suspect that there is a large exoplanet orbiting around the star. The wobble method is specifically only used for finding very large exoplanets. Planets such as Earth, would not be detected because it’s too small to be measured by these tools. 

Direct Imaging: 

Direct Imaging is the most hardest and restricted method to use when trying to discover exoplanets beyond the system. First, the star has to be extremely close to Earth in order to track the planet, Also, the exoplanets in this specific system have to be far enough from the star so they can identify the planet from the star’s light. Scientists are required to use a special instrument called a “coronagraph,” so they can block the light from the star. This helps them reveal any dim light of a planet that could be orbiting around the star. Around 10-30 exoplanets have been discovered using this method. 

Microlensing:

The Microlensing method is another difficult tool that scientists use for finding exoplanets. In order to discover exoplanets using this method, one star needs to pass in front of another star that is more distant from Earth. Scientists could then possibly measure the light from the distance star that is passing the system. They can then observe differences between the star and its exoplanet. This method can work even if the exoplanet is very distant from its star. This becomes an advantage over the more common methods such as the Transit or Wobble Methods. 

In conclusion to this topic, scientists have help researching planets beyond our Solar System by using common methods to figure out differences between a star, and the planet orbiting around it. The most common methods are the Transit and Wobble methods while the uncommon ones are the Microlensing and Direct Imaging methods. This project helped me understand how scientists are able to research, observe, and discover new planets every day.

Citations:

Earthsky.org. (2017). How do astronomers find exoplanets?. [online] Available at: http://earthsky.org/space/how-do-astronomers-discoverexoplanets [Accessed 4 Jun. 2018].

sciencenordic.com. (2018). How do scientists find new planets?. [online] Available at: http://sciencenordic.com/how-do-you-find-new-planet [Accessed 4 Jun. 2018].

Encyclopedia Britannica. (2018). Extrasolar planet | astronomy. [online] Available at: https://www.britannica.com/science/extrasolar-planet [Accessed 4 Jun. 2018].