What is an Exoplanet?
What is an Exoplanet?
An exoplanet is a planet that orbits a star outside the solar system.
Exoplanets can help us understand our universe better, and potentially find contact with other intelligent life. We can discover more unique planets, explore the universe, and meet other forms of life by learning more about these exoplanets. As of right now, 5,765 exoplanets have been discovered using various instruments and methods, but only 70 are possibly habitable. This is less than 0.01% of all these planets.
The first exoplanet was discovered by radio astronomers Aleksander Wolszczan and Dale Frail on January 9th, 1992. They announced that they discovered 2 planets orbiting a pulsar and it was later confirmed to be exoplanets. This is now considered the first definitive detection of exoplanets, and the start of this journey in science.
Discovering Exoplanets
How are exoplanets discovered?
Transit Method:
Using the transit method, the Kepler Space Telescope can catch “dips” in the light that stars emit. These dips represent planets blocking the star’s light while passing through in orbit. Using this information, the planet’s orbital size can be calculated using the time the planet takes to orbit the star and the mass of the star.
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Spectroscopy:
The James Webb Telescope uses spectroscopy to identify textures and landscapes. It captures infrared light from the stars and breaks it into colours. Depending on how the colours are blocked/filtered, the telescope can tell what the dust is made out of. Each atom and molecule has a unique spectroscopic signature.
Spectroscopy can also be used to identify water vapour in planetary disks and the atmosphere. Water is important when discovering planets because it represents being able to sustain life. Spectroscopy can help us identify planets that are similar to Earth, and discover other forms of life in the galaxy.
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Gravitational Microlensing:
As mentioned in the name, gravitational microlensing uses gravity to discover exoplanets since gravity can warp and bend starlight. A star in the foreground will magnify the light of the star behind it. If the star in the foreground has a planet in orbit, the telescope will see a spike in the intensity of light where the background star is.
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Radial Velocity:
Radial velocity is one of the key methods astronomers use to detect exoplanets. As a planet orbits a star, the star is being “tugged” at by the orbiting planet, which causes the star to wobble. Using telescopes, we can see the movement of the star and measure the wobble to determine whether there is a planet orbiting it.
Measuring Instruments
Measuring Instruments such as telescopes are tools that use different methods to discover exoplanets. These Instruments are the key for the discovery of life on other planets.
Habitable Worlds Observatory:
Habitable Worlds Observatory would be the first telescope designed specifically to search for signs of life on planets orbiting other stars. The Habitable Worlds Observatory is a large infrared/optical/ultraviolet space telescope. It is planned to be created/official in the 2040s.
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Kepler Space Telescope:
The Kepler Space Telescope was NASA’s first planet-hunting mission in 2009. It was built specifically for finding earth-sized exoplanets outside of our solar system. It found many hidden exoplanets and proved that there are more exoplanets than stars.
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Spitzer Space Telescope:
The Spitzer Space Telescope was created by NASA in 2003 it was part of NASA's Infrared Great Observatory. Over 16 years, it discovered the Trappist planets, Toi-700, the great rings on Saturn and explored many distant galaxies.
Hubble Space Telescope:
The Hubble Space Telescope was launched into the low orbit of Earth in 1990 and is still running. It helped discover exoplanets with its superb resolution and sensitivity. Some of its accomplishments include pinning down the age of the universe and the expansion rate of the universe.
CARMENES:
CARMENES(Calar Alto high-resolution search for M dwarfs with Exoearths using Near-infrared and optical Echelle Spectrographs) is a next-generation radial-velocity device that is currently being built. One of its key discovery was the Teegarden’s Star planets, which includes the exoplanet that is the most similar to Earth.
