Astronomers all around the world have been engaged in an endeavour to find another ‘Earth’ - a planet in the habitable zone that could support life as we know it. On 23rd July 2015, NASA’s Kepler mission returned bearing good news - the confirmation of an Earth-like planet. This planet, named Kepler-452b, is a super-Earth exoplanet orbiting a star similar to our sun, Kepler-452. This particular star is part of a constellation named Cygnus, and it is about 1800 light-years away from us.
Kepler-452 is 6 billion years old - that’s 1.5 billion years older than our sun. It maintains the same temperature, and is 20% brighter and has a diameter 10% larger. The discovery of Kepler-452b took place in the 20th anniversary year of the discovery that proved other suns can host planets, and it is a major milestone. There are various characteristics that scientists have evaluated which deem Kepler-452b worthy of the title ‘Earth 2.0’ or ‘Earth’s Cousin’. It has been determined that Kepler-452b takes about 385 Earth days to complete one orbit, which is just 5% higher than Earth’s 365 days. Moreover, it is in the famous ‘Goldilocks Zone’, the region in which a planet is the right distance away from its star to allow for life to possibly exist. Too close, and it would be too hot; too far, and it would be too cold. Earth too inhabits this zone. This distance is also necessary for water, which is essential for life, to remain liquid.
Astronomers have intriguingly been able to measure the mass of this planet that is so far we cannot even see it with our bare eyes. How? They waited for the planet to pass in front of the star, as it does once every orbit when seen from Earth. When the planet is in this position, it blocks a minuscule part of the star’s light. Upon measuring this decline in the light emitted, scientists have determined that Kepler-452b is about 60% larger in diameter than Earth, hence the name ‘super-Earth’.
Although the mass is not yet determined, it is suggested that it is rocky. If this is true, then the mass of Kepler-452b is about 5 times that of Earth. In this case, gravity would be twice as strong there! This would mean that just by inhabiting the planet, our bones would get stronger. There is also the possibility of the planet’s composition being similar to Neptune’s - that is to say, with a small rocky core surrounded by a thick mantle of ice and a gaseous envelope- the mass is going to be lesser. We also have not yet determined the atmosphere’s composition, but scientists are keenly aware that it is very unlikely that it is the same or even similar to Earth’s composition of primarily nitrogen and oxygen.
The quest for more Earth-like planets is still ongoing, and who knows what we may discover next? Maybe we’ll find a planet closer to us, more similar, and even extraterrestrial life! We just have to keep looking.
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