Kepler-452b

Kepler-452b

Exoplanet		List of exoplanets
Artist's concept of a rocky Earth-sized exoplanet in the habitable zone of its host star, possibly compatible with Kepler-452b’s known data
Parent star
Star		Kepler-452
Constellation		Cygnus
Right ascension	(α)	19h 44m 00.89s
Declination	(δ)	+44° 16′ 39.2″
Distance		1400 ly (430 pc)
Spectral type		G2
Mass	(m)	1.037+0.054 −0.047 M☉
Radius	(r)	1.11+0.15 −0.09 R☉
Temperature	(T)	5757±85 K
Metallicity	[Fe/H]	0.21±0.09
Age		6±2 Gyr
Physical characteristics
Mass	(m)	5 ± 2 (predicted) M⊕
Radius	(r)	1.5+0.32 −0.22 R⊕ (10.4+1.5 −1.3 Mm)
Stellar flux	(F⊙)	~1.10 ⊕
Density	(ρ)	6.4+6.8 −3.8 (predicted) g cm−3
Surface gravity	(g)	18.5+15.1 −10.0 (predicted) m/s² (1.9+1.5 −1.0 g)
Temperature	(T)	265+15 −13 K (−8+15 −13 °C, 17.6+27 −23.4 °F)
Discovery information
Discovery date		23 July 2015 (announced)
Discoverer(s)		Kepler Science Team
Discovery method		Transit
Discovery site		Kepler
Discovery status		Published
Orbital elements
Semi-major axis	(a)	1.046+0.019 −0.015 AU
Orbital period	(P)	384.843+0.007 −0.012 d
Inclination	(i)	89.806+0.134 −0.049°
Other designations
KOI-7016.01
Database references
Extrasolar Planets Encyclopaedia		data
SIMBAD		data
Exoplanet Archive		data
Open Exoplanet Catalogue		data

Kepler-452b (sometimes nicknamed Earth 2.0) is an exoplanet orbiting the G-class star Kepler-452. It was identified by the Kepler space telescope, and its discovery was announced by NASA on 23 July 2015. It is the first potentially rocky super-Earth planet discovered orbiting within the habitable zone of a star very similar to the Sun.

The planet is about 1,400 light-years away from the Solar System. At the speed of the New Horizons spacecraft, about 59,000 km/h (37,000 mph), it would take approximately 26 million years to get there.

Characteristics

Kepler-452b takes 385 Earth days to orbit its star. It is 50% bigger than Earth, and lies within the conservative habitable zone of its parent star.

It has a probable mass five times that of Earth, and its surface gravity is twice Earth's, though calculations of mass for exoplanets are only rough estimates. If it is a terrestrial planet, it is most likely a super-Earth with many active volcanoes due to its higher mass and density. The clouds on the planet would be thick and misty, covering much of the surface as viewed from space. From the surface, its star Kepler-452 would look almost identical to the Sun as viewed from the Earth.

Habitability potential

It is not known if Kepler-452b is a rocky planet but based on its small radius, Kepler-452b is likely rocky. It is not clear if Kepler-452b offers habitable environments. It orbits a G2V-type star, like the Sun, with nearly the same temperature and mass and 20% more luminous. However, the star is six billion years old, making it 1.5 billion years older than the Sun. At this point in its star's evolution, Kepler-452b is receiving 10% more energy from its parent star than Earth is currently receiving from the Sun. If Kepler-452b is a rocky planet, it may be subject to a runaway greenhouse effect similar to that seen on Venus. However, due to the planet being 50% bigger than Earth, it is likely to have an estimated mass of 5 M_⊕, which would prevent Kepler-452b from succumbing to the runaway greenhouse effect for another 500 million years, thus holding on to any oceans it may have for a longer period time compared to when Earth's oceans dry up. This in turn would be accompanied with the carbonate–silicate cycle being "buffed" in duration due to increased volcanic activity on Kepler-452b. This could allow any potential life on the surface to continue to evolve for another 500–900 million years before the habitable zone is pushed out of 452b's orbit.

Scientists with the SETI (Search for Extraterrestrial Intelligence) Institute have already begun targeting Kepler-452b, the first near-Earth-size world found in the habitable zone of a Sun-like star. SETI Institute researchers are using the Allen Telescope Array, a collection of 6-meter (20 feet) telescopes in the Cascade Mountains of California, to scan for radio transmissions from Kepler-452b. As of July 2015, the array has scanned the exoplanet on over 2 billion frequency bands, with no result. The telescopes will continue to scan over a total of 9 billion channels, searching for alien radio signals.

Notable Exoplanets – Kepler Space Telescope
Comparison of small planets found by Kepler in the habitable zone of their host stars.

Observation and exploration

Kepler-452b is 1,400 light years from Earth, each light year at 5.88 trillion miles, which means it would take the best part of a millennium-and-a-half to reach it if a spacecraft could travel at the speed of light. The speed of light is 668,000,000 mph (1.075×10⁹ km/h; 186,000 mi/s) and the fastest current space craft, the New Horizons unmanned probe that passed Pluto in July of 2015, travels at just 35,187 mph (56,628 km/h). At this rate, it would take the craft about 26 million years before it reached Kepler-452b, clearly an unthinkable amount of time.

Gallery

A diagram of the orbit of Kepler-452b within the Kepler-452 system, as compared to the inner Solar System and Kepler-186 system, and their respective projected habitable zones.   This artist's concept compares Earth (left) to Kepler-452b, which is about 50% larger in diameter.   Comparison of Kepler-452b and related exoplanets with Earth

See also

• List of potentially habitable exoplanets

External links

• NASA – Kepler Mission
• NASA – Kepler Discoveries – Summary Table
• Habitable Exolanets Catalog at UPR-Arecibo.
• Discovery and Validation of Kepler-452b: A 1.6 R⨁ Super Earth Exoplanet in the Habitable Zone of a G2 Star