Kepler-442b – a Near-Earth-sized Exoplanet

Kepler-442b is a super-Earth exoplanet in the habitable zone of a K-type star. It is a confirmed near-Earth-sized exoplanet, most likely rocky, orbiting within the habitable zone of the K-type main-sequence star Kepler-442 in the constellation Lyra, about 1,206 light-years (370 parsecs) from Earth. It has a mass of 2.36 Earths, takes 112.3 days to complete one orbit around its star, and is 0.409 AU away from it.

The planet orbits its host star at a distance of approximately 0.409 AU (61,200,000 km; 38,000,000 mi) with an orbital period of approximately 112.3 days, has a mass that is approximately 2.3 times that of Earth, and a radius that is approximately 1.34 times that of Earth. It is one of the more promising candidates for potential habitability because its parent star is at least 40% less massive than the Sun, allowing it to live for approximately 30 billion years.

It was discovered in 2015, and its discovery was announced. The planet was discovered by NASA’s Kepler spacecraft using the transit method, which measures the dimming effect caused by a planet as it passes in front of its star. On January 6, 2015, NASA announced the confirmation of the exoplanet.

Physical characteristics

The planet is most likely rocky, and it is classified as a Super-Earth, a planet with a greater mass and radius than Earth but less than the Ice Giants. Kepler 442b has a mass roughly double that of the Earth and a radius 30 percent larger. The equilibrium temperature, or the temperature of the planet if no atmosphere existed, is 233 K (-40°C; -40°F). Kepler 442b orbits its star at a distance of 38,000,000 miles (61,200,000 kilometers) and takes approximately 112 Earth days to complete one revolution. Determining the atmospheric composition of the planet cannot be conducted due to it being too far from the Earth.

Mass, radius, and temperature

Kepler-442b is a super-Earth, an exoplanet with a larger mass and radius than Earth but a smaller radius than the ice giants Uranus and Neptune. It has a temperature equilibrium of 233 K (40 °C; 40 °F). It has a diameter of 1.34 R☉. Due to its radius, it is most likely a rocky planet with a solid surface. The exoplanet’s mass is estimated to be 2.36 M☉. If Kepler-442b has a rocky composition similar to Earth, its surface gravity would be 30% greater than that of Earth.

Host star

The planet Kepler-442 orbits a (K-type) star. The star has a radius of 0.60 R☉ and a mass of 0.61 M☉. It has a temperature of 4402 K and is estimated to be 2.9 billion years old. The Sun, on the other hand, is 4.6 billion years old and has a temperature of 5778 K. With a metallicity (Fe/H) of 0.37, or 43 percent of the solar amount, the star is somewhat metal-poor. It has a luminosity (L) that is 12% that of the Sun.

The apparent magnitude of the star, or how bright it appears to us from Earth, is 14.76. As a result, it is too dim to see with the naked eye.


Kepler-442b orbits its host star for 112 days, 9 hours, 10 minutes, and 24 seconds, with an orbital radius roughly 0.4 times that of Earth (a little larger than the distance of Mercury from the Sun, which is about 0.38 AU). It receives roughly 70% of the sunlight that the Earth receives from the Sun.


The planet was announced to be within its star’s habitable zone, a region where liquid water could exist on the planet’s surface. It was described as one of the most Earth-like planets ever discovered in terms of size and temperature. A new index has been developed to assist researchers in determining which exoplanets are most likely to be habitable, allowing them to use this information when deciding which objects to focus space telescopes and other monitoring equipment on. It is just outside the zone (approximately 0.362 AU) where tidal forces from its host star would be sufficient to fully tidally lock it. Kepler-442b was thought to be the most habitable non-tidally locked exoplanet discovered as of July 2018.