Kepler-452b: How NASA’s space telescope found Earth’s cousin

NASA’s Kepler space telescope has found the first near-Earth-size planet, named Kepler-452b, in the “habitable zone” around a sun-like star.

This zone is known as The Goldilocks Zone, an area around a star where it’s warm enough for water to be liquid. In other words it’s similar to Earth’s orbit around the Sun, and therefore may offer just the right conditions for supporting life. Some scientists also believe that such habitable planets need to exist within galactic habitable zones, places where there are the necessary heavy elements to form rocky planets. Planets within Goldilocks Zones could be capable of supporting extraterrestrial life or, with the right atmosphere and gravitation, human colonies from Earth.

Kepler-452b: The facts

Kepler-452b Earth
An artist’s impression comparing Earth (left) to the new planet, called Kepler-452b (right)
    • Kepler-452b is 60 percent larger in diameter than Earth and is considered a super-Earth-size planet.
    • Its mass and composition have not yet been determined, but previous research suggests that planets the size of Kepler-452b have a good chance of being rocky.
    • While Kepler-452b is larger than Earth, its 385-day orbit is only 5 percent longer because the planet is 5 percent farther from its parent star Kepler-452 than Earth is from the Sun.
    • Kepler-452 is 6 billion years old, 1.5 billion years older than our sun, has the same temperature, is 20 percent brighter and has a diameter 10 percent larger.
    • The Kepler-452 system is located 1,400 light-years away in the constellation Cygnus.

What is the Kepler mission?

The Kepler mission is looking for planets with the potential to support life, either alien or human. Its aim is to look at the planetary systems around a range of stars and gather data on a wide variety of factors, such as the behaviour of gas giant planets, but one of its most particular objectives is to identify Earth-sized or larger planets in or near a star’s Goldilocks Zone.

Kepler itself is a space telescope akin to Hubble. It follows the Earth at a distance of one AU (Astronomical Unit or 92,955,887 miles, the average distance from the Earth to the Sun) in an orbit around the Sun, taking slightly longer than an Earth year to complete a circuit. Launched in March 2009, it’s designed to observe planets crossing across the face of their stars. The size of a planet affects the amount it dims the light from its parent star when occluded by it; Kepler is looking for relatively tiny fluctuations in the star’s light – around 0.01 per cent of its stellar magnitude.

The Kepler space telescope looks at one particular area of the sky which is not affected by light from the Sun from the angle at which Kepler observes it. This is because it uses a photometer to measure the light of stars, and sunlight would drastically affect the results. The star field it primarily observes is made up of the constellations Cygnus, Lyra and Draco.

Keplar Space Telescope annotated illustration
How the Keplar Space Telescope works

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Plus take a look at:

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How do planets form?

Astrophysicist Eric Ford from Pennsylvania State University discusses our current understanding of planet origins