What is an exoplanet ?
Exoplanet Meaning - Exoplanets (Extrasolar Planets) are planets that orbit a star other than Sun.
The nearest exoplanet from our solar system is Proxima Centauri b by a distance of about 4.24 light-years, which orbits a star called Proxima Centauri.
Till the date, we have 4,141 Exoplanets, and there are more than 40 exoplanets discovered in the Habitable Zone ( An orbital region where liquid water will be found and life will exist ).
Our galaxies (Milky way) has about 400 billion stars, and it can be possible that it has trillions of exoplanet.
The transit photometry method is the most effective way to find an exoplanet. When an exoplanet comes between earth and star (not the Sun) then a dips in the brightness of that star can be observed. Astronomers use Photometry (a curve b/w time and brightness of a star) to study dips in brightness.
The nearest exoplanet from our solar system is Proxima Centauri b by a distance of about 4.24 light-years, which orbits a star called Proxima Centauri.
Till the date, we have 4,141 Exoplanets, and there are more than 40 exoplanets discovered in the Habitable Zone ( An orbital region where liquid water will be found and life will exist ).
Our galaxies (Milky way) has about 400 billion stars, and it can be possible that it has trillions of exoplanet.
The transit photometry method is the most effective way to find an exoplanet. When an exoplanet comes between earth and star (not the Sun) then a dips in the brightness of that star can be observed. Astronomers use Photometry (a curve b/w time and brightness of a star) to study dips in brightness.
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| Transit photometey method Credit - NASA |
51 Pegasi b (also called Dimidium) was the first discovered exoplanet that is orbiting a star like our sun.
This exoplanet was found using the wobble method.
In this method, if a star is wobbling, it has an exoplanet.
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| Credit -Zhatt, Public domain, via Wikimedia Commons |
The wobbling of a star occurs because star and exoplanet are orbits around a point known as Barycenter. (Barycenter is central of mass between star and exoplanet)
{this all phenomenon is also seen between the sun and planet.}
{this all phenomenon is also seen between the sun and planet.}
Astronomers absorb the doppler shift due to steller wobble.
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| Credit -NASA |
[Same doppler effect that we hear motorcycles get high and low pitch]
Some times this method is also called the radial velocity method.
Direct imaging exoplanets, As his name suggests, involves taking the pictures of the exoplanet, but it's not easy, due to the distance. A Star is a billion times brighter than exoplanet, but in case of infrared wavelength, it is just million. So with this, Astronomers can easily capture a photo of an exoplanet near to our solar system.
First direct image of an 2M1207b(exoplanet) -
First direct image of an 2M1207b(exoplanet) -
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| 2M1207b -Exoplanet, CrediESO, CC BY 4.0 , via Wikimedia Commons |
There are other method to but they detect very less exoplanet Except - Microlensing.
NASA had launched Kepler Space Telescope mission in 2009 and retired in 2018 after valuable discoveries.
Smallest Exoplanet ever discovered -
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| IMAGE CREDIT - NASA |
L 98-59b is the smallest exoplanet ever discovered. It orbits the star M dwarf star - L 98-59 in 2.2 days. L 98-59c and L 98-59d exoplanets are also part of its system. It gets 22 times more energy from its host star than our Earth gain from the sun.
All three worlds are not in the habitable zone. The star is not half our sun and, it is only 8 times our earth while L 98-59b is 80% of our earth size. L 98-59b is located in Volans constellation and 32 lightyears away from our Earth. It has a temperature of 330°C.
L 98-59b is 10% smaller than the previous smallest star Kepler-37b, which is 20% larger than the moon. The exoplanet was spotted recently in the year 2018 by the transit method.
Transiting Exoplanet Survey Satellite (TESS) was launched in the year 2018 by SpaceX Falcon 9 rocket. And the mission was led by the Massachusetts Institute of Technology and NASA. TESS is designed to search for the extrasolar planet through the transit method. It covers 400 times a large area than the Kepler mission.
All three worlds are not in the habitable zone. The star is not half our sun and, it is only 8 times our earth while L 98-59b is 80% of our earth size. L 98-59b is located in Volans constellation and 32 lightyears away from our Earth. It has a temperature of 330°C.
L 98-59b is 10% smaller than the previous smallest star Kepler-37b, which is 20% larger than the moon. The exoplanet was spotted recently in the year 2018 by the transit method.
Transiting Exoplanet Survey Satellite (TESS) was launched in the year 2018 by SpaceX Falcon 9 rocket. And the mission was led by the Massachusetts Institute of Technology and NASA. TESS is designed to search for the extrasolar planet through the transit method. It covers 400 times a large area than the Kepler mission.
