Kepler-62f (also known by its Kepler Object of Interest designation ''KOI-701.04'') is a super-Earth

exoplanet An exoplanet or extrasolar planet is a planet outside the Solar System. The first confirmed detection of an exoplanet was in 1992 around a pulsar, and the first detection around a main-sequence star was in 1995. A different planet, first det ...

orbiting within the

habitable zone In astronomy and astrobiology, the habitable zone (HZ), or more precisely the circumstellar habitable zone (CHZ), is the range of orbits around a star within which a planetary surface can support liquid water given sufficient atmospheric pressu ...

of the star Kepler-62, the outermost of five such planets discovered around the star by

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

Kepler space telescope The Kepler space telescope is a defunct space telescope launched by NASA in 2009 to discover Earth-sized planets orbiting other stars. Named after astronomer Johannes Kepler, the spacecraft was launched into an Earth-trailing heliocentric orb ...

. It is located about from

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The first constellati ...

Lyra , from ; pronounced: ) is a small constellation. It is one of the 48 listed by the 2nd century astronomer Ptolemy, and is one of the modern 88 constellations recognized by the International Astronomical Union. Lyra was often represented on star ...

. Kepler-62f orbits its parent star at a distance of from its host star with an orbital period of roughly 267

days A day is the time period of a full rotation of the Earth with respect to the Sun. On average, this is 24 hours (86,400 seconds). As a day passes at a given location it experiences morning, afternoon, evening, and night. This daily cyc ...

, and has a radius of around 1.41 times that of Earth. It is one of the more promising candidates for potential

habitability Habitability is the adequacy of an environment for human living. Where housing is concerned, there are generally local ordinances which define habitability. If a residence complies with those laws, it is said to be habitable. In extreme environ ...

, as its parent star is a relatively quiet star, and has less mass than the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

– thus it can live up to a span of about 30 billion years or so. Based on its size, Kepler-62f is likely a

terrestrial Terrestrial refers to things related to land or the planet Earth, as opposed to extraterrestrial. Terrestrial may also refer to: * Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on o ...

or ocean-covered planet. However, key components of the exoplanet still need to be assessed to determine habitability; such as its

atmosphere An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...

if one exists, since it lies within the outer part of its host star's habitable zone. The

discovery Discovery may refer to: * Discovery (observation), observing or finding something unknown * Discovery (fiction), a character's learning something unknown * Discovery (law), a process in courts of law relating to evidence Discovery, The Discovery ...

of the exoplanet–along with

Kepler-62e Kepler-62e (also known by its Kepler Object of Interest designation KOI-701.03) is a super-Earth exoplanet (extrasolar planet) discovered orbiting within the habitable zone of Kepler-62, the second outermost of five such planets discovered by NAS ...

–was announced in April 2013 by

as part of the Kepler space telescope data release. The exoplanet was found by using the

transit method Methods of detecting exoplanets usually rely on indirect strategies – that is, they do not directly image the planet but deduce its existence from another signal. Any planet is an extremely faint light source compared to its parent star. For e ...

, in which the dimming effect that a planet causes as it crosses in front of its star is measured. According to scientists, it is a potential candidate to search for

extraterrestrial life Extraterrestrial life, or alien life (colloquially, aliens), is life that originates from another world rather than on Earth. No extraterrestrial life has yet been scientifically conclusively detected. Such life might range from simple forms ...

, and was chosen as one of the targets to study by the

Search for Extraterrestrial Intelligence The search for extraterrestrial intelligence (usually shortened as SETI) is an expression that refers to the diverse efforts and scientific projects intended to detect extraterrestrial signals, or any evidence of intelligent life beyond Earth. ...

(SETI) program.

Physical characteristics

Mass, radius and temperature

Kepler-62f is a super-Earth, placing it within the class of exoplanets with a radius and mass bigger than Earth, but smaller than that of the ice giants

Neptune Neptune is the eighth and farthest known planet from the Sun. It is the List of Solar System objects by size, fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 t ...

and

Uranus Uranus is the seventh planet from the Sun. It is a gaseous cyan-coloured ice giant. Most of the planet is made of water, ammonia, and methane in a Supercritical fluid, supercritical phase of matter, which astronomy calls "ice" or Volatile ( ...

. It has an

equilibrium temperature The planetary equilibrium temperature is a theoretical temperature that a planet would be if it were in radiative equilibrium, typically under the assumption that it radiates as a black body being heated only by its parent star. In this model, th ...

of , close to that of

Mars Mars is the fourth planet from the Sun. It is also known as the "Red Planet", because of its orange-red appearance. Mars is a desert-like rocky planet with a tenuous carbon dioxide () atmosphere. At the average surface level the atmosph ...

’s temperature. It has a radius of 1.46 , placing it below the radius of ≥1.6 where it would otherwise be a

mini-Neptune A Mini-Neptune (sometimes known as a gas dwarf or transitional planet) is a planet less massive than Neptune but resembling Neptune in that it has a thick hydrogen-helium atmosphere, probably with deep layers of ice, rock or liquid oceans (made o ...

with a volatile composition, with no solid surface. Due to its radius, it is likely a

rocky planet A terrestrial planet, tellurian planet, telluric planet, or rocky planet, is a planet that is composed primarily of silicate, rocks or metals. Within the Solar System, the terrestrial planets accepted by the IAU are the inner planets closest to ...

. However, the mass isn't constrained yet, estimates place an upper limit of <35 , the real mass is expected to be significantly lower than this. The

Planetary Habitability Laboratory The Planetary Habitability Laboratory (PHL) is a research remote laboratory intended to study the habitability of the Solar System and other stellar systems, specifically, potentially habitable exoplanets. The PHL is managed by the University of ...

estimated a mass of around 2.6 , assuming a rocky Earth-like composition.

Host star

The planet orbits a ( K-type)

star A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sk ...

named Kepler-62, orbited by a total of five known planets. The star has a mass of 0.69 and a radius of 0.64 . It has a temperature of 4925 K and is 7 billion years old. In comparison, the

is 4.6 billion years old and has a temperature of 5778 K. The star is somewhat metal-poor, with a

metallicity In astronomy, metallicity is the Abundance of the chemical elements, abundance of Chemical element, elements present in an object that are heavier than hydrogen and helium. Most of the normal currently detectable (i.e. non-Dark matter, dark) matt ...

( e/H of −0.37, or 42% of the solar amount. Its luminosity () is 21% that of the Sun. The star's

apparent magnitude Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), ...

, or how bright it appears from Earth's perspective, is 13.65. Therefore, it is too dim to be seen with the naked eye.

Orbit

Kepler-62f orbits its host star every 267.29 days at a

semi-major axis In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the longe ...

distance of about 0.718

astronomical unit The astronomical unit (symbol: au or AU) is a unit of length defined to be exactly equal to . Historically, the astronomical unit was conceived as the average Earth-Sun distance (the average of Earth's aphelion and perihelion), before its m ...

s (107,400,000 km, 66,700,000 mi), which is roughly the same as

Venus Venus is the second planet from the Sun. It is often called Earth's "twin" or "sister" planet for having almost the same size and mass, and the closest orbit to Earth's. While both are rocky planets, Venus has an atmosphere much thicker ...

's semi-major axis from the Sun. Compared to Earth, this is about seven-tenths of the distance from it to the Sun. Kepler-62f is estimated to receive about 41% of the amount of

sunlight Sunlight is the portion of the electromagnetic radiation which is emitted by the Sun (i.e. solar radiation) and received by the Earth, in particular the visible spectrum, visible light perceptible to the human eye as well as invisible infrare ...

that Earth does from the Sun, which is comparable to

, which receives 43%.

Habitability

Given the planet's age (7 ± 4 billion years), irradiance (0.41 ± 0.05 times Earth's) and radius (1.46 ± 0.07 times Earth's), a rocky (silicate-iron) composition with the addition of a possibly substantial amount of water is considered plausible. A modeling study indicates it is likely that a great majority of planets in its size range are completely covered by ocean. If its density is the same as Earth's, its mass would be 1.41³ or 2.80 times Earth's. The planet has the potential for hosting a

moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

according to a study of tidal effects on potentially habitable planets. The planet may be the only habitable-zone candidate which would avoid desiccation by irradiation from the host star at its current location.

Climate

Although Kepler-62f may be an ocean-covered planet possessing rock and water at the surface, it is the farthest out from its star, so without a supplementary amount of

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

(), it may be a planet covered entirely in ice. In order for Kepler-62f to sustain an Earth-like climate (with an average temperature of around , at least of carbon dioxide would have to be present in the planet's atmosphere. On 13 May 2016, researchers at

University of California, Los Angeles The University of California, Los Angeles (UCLA) is a public university, public Land-grant university, land-grant research university in Los Angeles, California, United States. Its academic roots were established in 1881 as a normal school the ...

(UCLA) announced that they had found various scenarios that allow the exoplanet to be habitable. They tested several simulations based on Kepler-62f having an atmosphere that ranges in thickness from the same as Earth's all the way up to 12 times thicker than our planet's, various concentrations of carbon dioxide in its atmosphere, ranging from the same amount as is in the Earth's atmosphere up to 2,500 times that level and several different possible configurations for its orbital path. In June 2018, studies suggest that Kepler-62f may have seasons and a climate similar to those on Earth.

Other factors

Because it is the outermost planet of its star system, the effects of tidal evolution from the inner planets and the host star on Kepler-62f are not likely to have had significant outcomes over its lifetime. The axial tilt is likely to have been unchanged, and thus, the planet may have an axial tilt (anywhere from 14°–30°) and rotational period somewhat similar to Earth. This can further make the planet more sustainable for habitability, as it would be able to transfer heat to the night side, instead of it being a planet with its surface being half water and half ice. K-type stars like Kepler-62 can live for approximately 20–40 billion years, 2 to 4 times longer than the estimated lifetime of the Sun. The low stellar activity of orange dwarfs like Kepler-62, creates a relatively benign radiation environment for planets orbiting in their habitable zones, increasing their potential habitability. One review essay in 2015 concluded that Kepler-62f, along with the exoplanets Kepler-186f and Kepler-442b, were likely the best candidates for being potentially habitable planets.Kepler Johannes Kepler (27 December 1571 – 15 November 1630) was a German astronomer, mathematician, astrologer, natural philosopher and writer on music. He is a key figure in the 17th-century Scientific Revolution, best known for his laws of p ...

Physical characteristics

Mass, radius and temperature

Host star

Orbit

Habitability

Climate

Other factors

Follow-up studies

Extraterrestrial intelligence target

See also

References

External links