Kepler-452b: Difference between revisions

Kepler-452b
	Artist's impression of Kepler-452b (center), depicted here as a rocky planet in the habitable zone with extensive cloud cover. The actual appearance and composition of the exoplanet is unknown.
Discovery
Discovered by	Kepler Science team
Discovery site	Kepler
Discovery date	23 July 2015 (announced)
Detection method	Transit
Designations
Alternative names	KOI-7016.01
Orbital characteristics
Semi-major axis	1.046+0.019; −0.015 AU
Orbital period (sidereal)	384.843+0.007; −0.012 d
Inclination	89.806+0.134; −0.049
Star	Kepler-452
Physical characteristics
Mean radius	1.5+0.32; −0.22 R🜨
Mass	5 ± 2 ME
Surface gravity	1.9+1.5; −1.0 (est.) g
Temperature	Teq: 265K+15; −13 (265 K (−8 °C; 17 °F))

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Kepler-452b (sometimes quoted to be an Earth 2.0 or Earth's Cousin^[4]^[5] based on its characteristics; also known by its Kepler object of interest designation KOI-7016.01) is a candidate^[6]^[7] super-Earth exoplanet orbiting within the inner edge of the habitable zone of the sun-like star Kepler-452 and is the only planet in the system discovered by the Kepler space telescope. It is located about 1,800 light-years (550 pc)^[8] from Earth in the constellation of Cygnus.

Kepler-452b orbits its star at a distance of 1.04 AU (156 million km; 97 million mi) from its host star (nearly the same distance as Earth from the Sun), with an orbital period of roughly 385 days, has a mass at least five times that of Earth, and has a radius of around 1.5 times that of Earth. It is the first potentially rocky super-Earth^[9] planet discovered orbiting within the habitable zone of a very Sun-like star.^[10] However, it is unknown if it is entirely habitable, as it is receiving slightly more energy from its star than Earth and could be subjected to a runaway greenhouse effect.

The Kepler space telescope identified the exoplanet, and its discovery was announced by NASA on 23 July 2015.^[11] The planet is about 1,800 light-years (550 pc) away from the Solar System. At the speed of the New Horizons spacecraft, at about 59,000 km/h (16,000 m/s; 37,000 mph), it would take approximately 30 million years to get there.^[12]

Physical characteristics

Mass, radius and temperature

Kepler-452b has a probable mass five times that of Earth, and its surface gravity is nearly twice as much as Earth's, though calculations of mass for exoplanets are only rough estimates.^[3] 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.

The planet takes 385 Earth days to orbit its star.^[13] Its radius is 50% larger than Earth's, and lies within the conservative habitable zone of its parent star.^[3]^[14] It has an equilibrium temperature of 265 K (−8 °C; 17 °F), a little warmer than Earth.

Host star

The host star, Kepler-452, is a G-type and has about the same mass as the sun, only 3.7% more massive and 11% larger. It has a surface temperature of 5757 K, nearly the same as the Sun, which has a surface temperature of 5778 K.^[15] The star's age is estimated to be about 6 billion years old, about 1.5 billion years older than the Sun, which is estimated to have existed for 4.6 billion years. Kepler-452b has been in Kepler-452's habitable zone for most of its existence, a duration just over six billion years.^[16]

From the surface of Kepler-452b, its star would look almost identical to the Sun as viewed from the Earth.^[17] The star's apparent magnitude, or how bright it appears from Earth's perspective, is 13.426; therefore, it is too dim to be seen with the naked eye.

Orbit

Kepler-452b orbits its host star with an orbital period of 385 days and an orbital radius of about 1.04 AU, nearly the same as Earth's (1 AU). Kepler-452b is most likely not tidally locked and has a circular orbit. Its host star, Kepler-452, is about 20% more luminous than the Sun (L = 1.2 L_☉).

Potential habitability

Comparison of Kepler-452b and related exoplanets with Earth.

It is not known if Kepler-452b is a rocky planet^[4] but based on its small radius, Kepler-452b is likely to be rocky.^[11] It is not clear if Kepler-452b offers habitable environments. It orbits a G2V-type star, like the Sun, which is 20% more luminous, with nearly the same temperature and mass.^[13] However, the star is roughly 6 billion years old, making it 1.5 billion years older than the Sun. At this point in its star's evolution, Kepler-452b is currently receiving 10% more energy from its parent star than Earth is currently receiving from the Sun.^[10] If Kepler-452b is a rocky planet, it may be subject to a runaway greenhouse effect similar to that seen on Venus.^[18]

"Delayed" runaway greenhouse effect

However, due to the planet Kepler-452b being 50 percent bigger in terms of size, it is likely to have an estimated mass of 5 M_E, which could allow it to hold on to any oceans it may have for a longer period, preventing Kepler-452b from succumbing to runaway greenhouse effect for another 500 million years.^[18] This, in turn, would be accompanied by the carbonate–silicate cycle being "buffered", extending its lifetime due to increased volcanic activity on Kepler-452b.^[19] This could allow any potential life on the surface to inhabit the planet for another 500–900 million years before the habitable zone is pushed beyond Kepler-452b's orbit.

Discovery and follow-up studies

In 2009, NASA's Kepler space telescope was observing stars on its photometer, the instrument it uses to detect transit events, in which a planet crosses in front of and dims its host star for a brief and roughly regular time. In this last test, Kepler observed 50000 stars in the Kepler Input Catalog, including Kepler-452; the preliminary light curves were sent to the Kepler science team for analysis, who chose obvious planetary companions from the bunch for follow-up by other telescopes. Observations for the potential exoplanet candidates took place between 13 May 2009 and 17 March 2012. Kepler-452b exhibited a transit that occurred roughly every 385 days, and it was eventually concluded that a planetary body was responsible. The discovery was announced by NASA on 23 July 2015.^[11]

At a distance of nearly 1,800 light-years (550 pc), Kepler-452b is too remote for current telescopes or the next generation of planned telescopes to determine its true mass or whether it has an atmosphere. The Kepler space telescope focused on a single small region of the sky but next-generation planet-hunting space telescopes, such as TESS and CHEOPS, will examine nearby stars throughout the sky with follow up studies planned for these closer exoplanets by the James Webb Space Telescope and future large ground-based telescopes to analyze their atmospheres, determine masses, and infer compositions.

A study in 2018 by Mullally et al. claimed that statistically, Kepler-452b has not been proven to exist and must still be considered a candidate.^[6] However, Kepler-452b is still a possible planet and has not been shown to be a false positive.^[6]

SETI targeting

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.^[20] 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 analysis.^[20]

Observation and exploration

Kepler-452b is 1,800 light-years (550 parsecs) from Earth. The fastest current spacecraft, the New Horizons uncrewed probe that passed Pluto in July 2015, travels at just 56,628 km/h (15,730 m/s; 35,187 mph; 0.00037853 AU/h).^[5] At that speed, it would take a spacecraft about 26 million years to reach Kepler-452b from Earth, if it were going in that direction.^[5]

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

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.

References

^ ^a ^b ^c ^d "NASA Exoplanet Archive – Confirmed Planet Overview – Kepler-452b". NASA Exoplanet Archive. 2009. Archived from the original on 24 July 2015. Retrieved 23 July 2008.
^ "NASA's Kepler Mission Discovers Bigger, Older Cousin to Earth". National Aeronautics and Space Administration. 23 July 2015. Archived from the original on 15 August 2015. Retrieved 10 June 2016.
^ ^a ^b ^c Feltman, Rachel (23 July 2015). "Scientists discover 12 new potential Earth-like planets". The Washington Post. Archived from the original on 18 July 2020. Retrieved 23 July 2015.
^ ^a ^b Rincon, Paul (23 July 2015). "'Earth 2.0' found in Nasa Kepler telescope haul". BBC News. Archived from the original on 19 July 2020. Retrieved 24 July 2015.
^ ^a ^b ^c "Kepler-452b: How long would it take humans to reach 'Earth 2' and could we live there?". 28 July 2015. Archived from the original on 5 May 2016. Retrieved 9 January 2016.
^ ^a ^b ^c Mullally, Fergal; Thompson, Susan E.; Coughlin, Jeffrey L.; Burke, Christopher J.; Rowe, Jason F. (May 2018). "Kepler's Earth-like Planets Should Not Be Confirmed without Independent Detection: The Case of Kepler-452b". The Astronomical Journal. 155 (5): 210. arXiv:1803.11307. Bibcode:2018AJ....155..210M. doi:10.3847/1538-3881/aabae3.
^ Burke, Christopher J.; Mullally, F.; Thompson, Susan E.; Coughlin, Jeffrey L.; Rowe, Jason F. (April 2019). "Re-evaluating Small Long-period Confirmed Planets from Kepler". The Astronomical Journal. 157 (4): 143. arXiv:1901.00506. Bibcode:2019AJ....157..143B. doi:10.3847/1538-3881/aafb79.
^ Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
^ "The Habitable Exoplanets Catalog – Planetary Habitability Laboratory @ UPR Arecibo". upr.edu. Archived from the original on 11 February 2018. Retrieved 23 July 2015.
^ ^a ^b Chou, Felicia; Johnson, Michele (23 July 2015). "NASA's Kepler Mission Discovers Bigger, Older Cousin to Earth" (Press release). NASA. Archived from the original on 7 October 2015. Retrieved 23 July 2015.
^ ^a ^b ^c Jenkins, Jon M.; Twicken, Joseph D.; Batalha, Natalie M.; et al. (23 July 2015). "Discovery and Validation of Kepler-452b: A 1.6 R_🜨 Super Earth Exoplanet in the Habitable Zone of a G2 Star" (PDF). The Astronomical Journal. 150 (2): 56. arXiv:1507.06723. Bibcode:2015AJ....150...56J. doi:10.1088/0004-6256/150/2/56. ISSN 1538-3881. S2CID 26447864. Archived (PDF) from the original on 5 July 2016. Retrieved 24 July 2015.
^ "NASA telescope discovers Earth-like planet in star's 'habitable zone". BNO News. 23 July 2015. Archived from the original on 4 March 2016. Retrieved 23 July 2015.
^ ^a ^b Overbye, Dennis (24 July 2015). "Kepler Data Reveals What Might Be Best 'Goldilocks' Planet Yet". The New York Times. Archived from the original on 24 July 2015. Retrieved 23 July 2015.
^ Witze, Alexandra (23 July 2015). "NASA spies Earth-sized exoplanet orbiting Sun-like star". Nature. Archived from the original on 23 November 2019. Retrieved 23 July 2015.
^ Fraser Cain (15 September 2008). "Temperature of the Sun". Universe Today. Archived from the original on 29 August 2010. Retrieved 19 February 2011.
^ Bohan, Elise; Dinwiddie, Robert; Challoner, Jack; Stuart, Colin; Harvey, Derek; Wragg-Sykes, Rebecca; Chrisp, Peter; Hubbard, Ben; Parker, Phillip; et al. (Writers) (February 2016). Big History. Foreword by David Christian (1st American ed.). New York: DK. p. 77. ISBN 978-1-4654-5443-0. OCLC 940282526. Archived from the original on 8 September 2024. Retrieved 18 March 2023.
^ NASA Kepler press conference. 23 July 2015.
^ ^a ^b Lugmayr, Luigi (23 July 2015). "Kepler-452b details unveiled". I4U News. Archived from the original on 9 October 2019. Retrieved 23 July 2015.
^ "Is Earth's Closest Cousin A Dying Planet?". Gizmodo.com. 30 July 2015. Archived from the original on 19 May 2016. Retrieved 24 May 2016.
^ ^a ^b "SETI Targets Kepler-452b, Earth's 'Cousin,' in Search for Alien Life". Space.com. 31 July 2015. Archived from the original on 20 July 2020. Retrieved 9 January 2016.

External links

[NASA-EPA-Kepler452b-1] "NASA Exoplanet Archive – Confirmed Planet Overview – Kepler-452b". NASA Exoplanet Archive. 2009. Archived from the original on 24 July 2015. Retrieved 23 July 2008.

[2] "NASA's Kepler Mission Discovers Bigger, Older Cousin to Earth". National Aeronautics and Space Administration. 23 July 2015. Archived from the original on 15 August 2015. Retrieved 10 June 2016.

[Feltman-3] Feltman, Rachel (23 July 2015). "Scientists discover 12 new potential Earth-like planets". The Washington Post. Archived from the original on 18 July 2020. Retrieved 23 July 2015.

[RinconP2015-4] Rincon, Paul (23 July 2015). "'Earth 2.0' found in Nasa Kepler telescope haul". BBC News. Archived from the original on 19 July 2020. Retrieved 24 July 2015.

[express.co.uk-5] "Kepler-452b: How long would it take humans to reach 'Earth 2' and could we live there?". 28 July 2015. Archived from the original on 5 May 2016. Retrieved 9 January 2016.

[Mullally2018-6] Mullally, Fergal; Thompson, Susan E.; Coughlin, Jeffrey L.; Burke, Christopher J.; Rowe, Jason F. (May 2018). "Kepler's Earth-like Planets Should Not Be Confirmed without Independent Detection: The Case of Kepler-452b". The Astronomical Journal. 155 (5): 210. arXiv:1803.11307. Bibcode:2018AJ....155..210M. doi:10.3847/1538-3881/aabae3.

[Burke2019-7] Burke, Christopher J.; Mullally, F.; Thompson, Susan E.; Coughlin, Jeffrey L.; Rowe, Jason F. (April 2019). "Re-evaluating Small Long-period Confirmed Planets from Kepler". The Astronomical Journal. 157 (4): 143. arXiv:1901.00506. Bibcode:2019AJ....157..143B. doi:10.3847/1538-3881/aafb79.

[GaiaDR3-8] Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.

[PHL-9] "The Habitable Exoplanets Catalog – Planetary Habitability Laboratory @ UPR Arecibo". upr.edu. Archived from the original on 11 February 2018. Retrieved 23 July 2015.

[Chou-10] Chou, Felicia; Johnson, Michele (23 July 2015). "NASA's Kepler Mission Discovers Bigger, Older Cousin to Earth" (Press release). NASA. Archived from the original on 7 October 2015. Retrieved 23 July 2015.

[Jenkins2015-11] Jenkins, Jon M.; Twicken, Joseph D.; Batalha, Natalie M.; et al. (23 July 2015). "Discovery and Validation of Kepler-452b: A 1.6 R_🜨 Super Earth Exoplanet in the Habitable Zone of a G2 Star" (PDF). The Astronomical Journal. 150 (2): 56. arXiv:1507.06723. Bibcode:2015AJ....150...56J. doi:10.1088/0004-6256/150/2/56. ISSN 1538-3881. S2CID 26447864. Archived (PDF) from the original on 5 July 2016. Retrieved 24 July 2015.

[bno-12] "NASA telescope discovers Earth-like planet in star's 'habitable zone". BNO News. 23 July 2015. Archived from the original on 4 March 2016. Retrieved 23 July 2015.

[Overbye-13] Overbye, Dennis (24 July 2015). "Kepler Data Reveals What Might Be Best 'Goldilocks' Planet Yet". The New York Times. Archived from the original on 24 July 2015. Retrieved 23 July 2015.

[Witze-14] Witze, Alexandra (23 July 2015). "NASA spies Earth-sized exoplanet orbiting Sun-like star". Nature. Archived from the original on 23 November 2019. Retrieved 23 July 2015.

[15] Fraser Cain (15 September 2008). "Temperature of the Sun". Universe Today. Archived from the original on 29 August 2010. Retrieved 19 February 2011.

[:022-16] Bohan, Elise; Dinwiddie, Robert; Challoner, Jack; Stuart, Colin; Harvey, Derek; Wragg-Sykes, Rebecca; Chrisp, Peter; Hubbard, Ben; Parker, Phillip; et al. (Writers) (February 2016). Big History. Foreword by David Christian (1st American ed.). New York: DK. p. 77. ISBN 978-1-4654-5443-0. OCLC 940282526. Archived from the original on 8 September 2024. Retrieved 18 March 2023.

[17] NASA Kepler press conference. 23 July 2015.

[Lugmayr-18] Lugmayr, Luigi (23 July 2015). "Kepler-452b details unveiled". I4U News. Archived from the original on 9 October 2019. Retrieved 23 July 2015.

[Kep452bAdvancedEarth2.0-19] "Is Earth's Closest Cousin A Dying Planet?". Gizmodo.com. 30 July 2015. Archived from the original on 19 May 2016. Retrieved 24 May 2016.

[space.com-20] "SETI Targets Kepler-452b, Earth's 'Cousin,' in Search for Alien Life". Space.com. 31 July 2015. Archived from the original on 20 July 2020. Retrieved 9 January 2016.

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@@ Line 1: / Line 1: @@
-{{short description|Extrasolar planet in the constellation Cygnus}}
+{{short description|Super-Earth exoplanet candidate orbiting Kepler-452}}
-{{Use dmy dates|date=March 2019}}
+{{Use dmy dates|date=March 2018}}
 {{Infobox planet
 | name                     = Kepler-452b
 | image                    = Kepler-452b artist concept.jpg
-| caption                  = Artist's impression of Kepler-452b ''(center)'', depicted here as a [[terrestrial planet|rocky planet]]  in the [[habitable zone]] with extensive cloud cover. The actual appearance of the exoplanet is unknown.
+| caption                  = Artist's impression of Kepler-452b ''(center)'', depicted here as a [[terrestrial planet|rocky planet]] in the [[habitable zone]] with extensive cloud cover. The actual appearance and composition of the exoplanet is unknown.
 <!-- DISCOVERY           -->
-| discoverer               = Kepler Science Team
+| discoverer               = Kepler Science team
 | discovery_site           = ''[[Kepler telescope|Kepler]]''
 | discovered               = 23 July 2015 (announced)
@@ Line 12: / Line 12: @@
 <!-- DESIGNATIONS        -->
 | alt_names                = KOI-7016.01
 <!-- ORBITAL             -->
 | apsis                    = astron
-| semimajor                = 1.046{{±|0.019|0.015}}<ref name="NASA-EPA-Kepler452b">{{cite web |title=NASA Exoplanet Archive – Confirmed Planet Overview – Kepler-452b
+| semimajor                = 1.046{{±|0.019|0.015}}<ref name="NASA-EPA-Kepler452b">{{cite web |title=NASA Exoplanet Archive – Confirmed Planet Overview – Kepler-452b |url=http://exoplanetarchive.ipac.caltech.edu/cgi-bin/DisplayOverview/nph-DisplayOverview?objname=Kepler-452+b |year=2009 |work=[[NASA Exoplanet Archive]] |access-date=23 July 2008 |archive-date=24 July 2015 |archive-url=https://archive.today/20150724003816/http://exoplanetarchive.ipac.caltech.edu/cgi-bin/DisplayOverview/nph-DisplayOverview?objname=Kepler-452+b |url-status=live }}</ref> [[astronomical unit|AU]]
-|url=http://exoplanetarchive.ipac.caltech.edu/cgi-bin/DisplayOverview/nph-DisplayOverview?objname=Kepler-452+b |year=2009 |work=[[NASA Exoplanet Archive]] |access-date=23 July 2009 }}</ref> [[astronomical unit|AU]]
 | period                   = 384.843{{±|0.007|0.012}}<ref name="NASA-EPA-Kepler452b" /> [[day|d]]
 | inclination              = 89.806{{±|0.134|0.049}}
@@ Line 22: / Line 21: @@
 | mean_radius              = 1.5{{±|0.32|0.22}}<ref name="NASA-EPA-Kepler452b" /> {{Earth radius|link=y}}
 | mass                     = 5 ± 2<ref>{{cite web|url=http://kepler.nasa.gov/news/index.cfm?FuseAction=ShowNews&NewsID=393|archive-url=https://web.archive.org/web/20150815125616/http://kepler.nasa.gov/news/index.cfm?FuseAction=ShowNews&NewsID=393|url-status=dead|archive-date=15 August 2015|title=NASA's Kepler Mission Discovers Bigger, Older Cousin to Earth|work=National Aeronautics and Space Administration|date=23 July 2015|access-date=10 June 2016}}</ref> {{Earth mass|link=y}}
-| surface_grav             = 1.9{{±|1.5|1.0}} (est.) [[g-force|g]]
+| surface_grav             = 1.9{{±|1.5|1.0}} (est.) [[g-force|g]]<ref name=Feltman/>
-| single_temperature       = [[Planetary equilibrium temperature|''T''<sub>eq</sub>]]: {{convert|265|K|C F}}<ref name="NASA-EPA-Kepler452b" />
+| single_temperature       = [[Planetary equilibrium temperature|''T''<sub>eq</sub>]]: 265K{{±|15|13}} ({{Convert|265|K|C F}})<ref name="NASA-EPA-Kepler452b" />
 <!-- ATMOSPHERE          -->
 <!-- NOTES               -->
 }}
-'''Kepler-452b''' (a planet sometimes quoted to be an ''Earth 2.0'' or ''Earth's Cousin''<ref name="RinconP2015">{{cite news |last=Rincon |first=Paul |url=https://www.bbc.com/news/science-environment-33641648 |title='Earth 2.0' found in Nasa Kepler telescope haul |publisher=[[BBC News]] |date=23 July 2015 |access-date=24 July 2015 }}</ref><ref name="express.co.uk">[http://www.express.co.uk/news/science/594133/Kepler-452b-How-long-take-humans-reach-Earth-2-could-we-live-there Kepler-452b: How long would it take humans to reach 'Earth 2' and could we live there?]</ref> based on its characteristics; also known by its [[Kepler Object of Interest]] designation ''KOI-7016.01'') is a [[super-Earth]] [[exoplanet]] orbiting within the inner edge of the [[habitable zone]] of the [[solar analog|Sun-like]] star [[Kepler-452]], and is the only planet in the system discovered by ''Kepler''. It is located about {{convert|1402|ly|pc}} from [[Earth]] in the constellation of [[Cygnus (constellation)|Cygnus]].
+'''Kepler-452b''' (sometimes quoted to be an ''Earth 2.0'' or ''Earth's Cousin''<ref name="RinconP2015">{{cite news |last=Rincon |first=Paul |url=https://www.bbc.com/news/science-environment-33641648 |title='Earth 2.0' found in Nasa Kepler telescope haul |publisher=[[BBC News]] |date=23 July 2015 |access-date=24 July 2015 |archive-date=19 July 2020 |archive-url=https://web.archive.org/web/20200719093632/https://www.bbc.com/news/science-environment-33641648 |url-status=live }}</ref><ref name="express.co.uk">{{Cite web |url=http://www.express.co.uk/news/science/594133/Kepler-452b-How-long-take-humans-reach-Earth-2-could-we-live-there |title=Kepler-452b: How long would it take humans to reach 'Earth 2' and could we live there? |date=28 July 2015 |access-date=9 January 2016 |archive-date=5 May 2016 |archive-url=https://web.archive.org/web/20160505035926/http://www.express.co.uk/news/science/594133/Kepler-452b-How-long-take-humans-reach-Earth-2-could-we-live-there |url-status=live }}</ref> based on its characteristics; also known by its [[Kepler object of interest]] designation ''KOI-7016.01'') is a candidate<ref name="Mullally2018"/><ref name="Burke2019"/> [[super-Earth]] [[exoplanet]] orbiting within the inner edge of the [[habitable zone]] of the [[Solar analog|sun-like]] star [[Kepler-452]] and is the only planet in the system discovered by the [[Kepler space telescope]]. It is located about {{convert|1800|ly|pc}}<ref name=GaiaDR3>{{cite Gaia DR3|2079597124345617280}}</ref> from [[Earth]] in the constellation of [[Cygnus (constellation)|Cygnus]].
-Kepler-452b orbits its star at a distance of {{convert|1.04|AU|abbr=on}} from its host star (nearly the same distance as Earth from the Sun), with an orbital period of roughly 384 [[days]], has a mass at least 5x times that of Earth, and has a radius of around 1.5 times that of Earth.  It is the first potentially rocky [[super-Earth]]<ref name=PHL>{{cite web|url=http://phl.upr.edu/projects/habitable-exoplanets-catalog|title=The Habitable Exoplanets Catalog – Planetary Habitability Laboratory @ UPR Arecibo|work=upr.edu}}</ref> planet discovered orbiting within the [[Circumstellar habitable zone|habitable zone]] of a star very similar to the [[Sun]].<ref name=Chou>{{cite press release|last1=Chou|first1=Felicia|last2=Johnson|first2=Michele|title=NASA's Kepler Mission Discovers Bigger, Older Cousin to Earth|url=http://www.nasa.gov/press-release/nasa-kepler-mission-discovers-bigger-older-cousin-to-earth|access-date=23 July 2015|agency=NASA|date=23 July 2015}}</ref> However, it is not known if it is completely habitable, as it is receiving slightly more energy than Earth is, and could possibly be subjected to a [[runaway greenhouse effect]].
+Kepler-452b orbits its star at a distance of {{convert|1.04|AU|e6km e6mi|abbr=unit}} from its host star (nearly the same distance as Earth from the Sun), with an orbital period of roughly 385 [[Day|days]], has a mass at least five times that of Earth, and has a radius of around 1.5 times that of Earth. It is the first potentially rocky [[super-Earth]]<ref name=PHL>{{cite web|url=http://phl.upr.edu/projects/habitable-exoplanets-catalog|title=The Habitable Exoplanets Catalog – Planetary Habitability Laboratory @ UPR Arecibo|work=upr.edu|access-date=23 July 2015|archive-date=11 February 2018|archive-url=https://web.archive.org/web/20180211104253/http://phl.upr.edu/projects/habitable-exoplanets-catalog|url-status=live}}</ref> planet discovered orbiting within the [[Circumstellar habitable zone|habitable zone]] of a very Sun-like star.<ref name=Chou>{{cite press release|last1=Chou|first1=Felicia|last2=Johnson|first2=Michele|title=NASA's Kepler Mission Discovers Bigger, Older Cousin to Earth|url=http://www.nasa.gov/press-release/nasa-kepler-mission-discovers-bigger-older-cousin-to-earth|access-date=23 July 2015|agency=NASA|date=23 July 2015|archive-date=7 October 2015|archive-url=https://web.archive.org/web/20151007035447/http://www.nasa.gov/press-release/nasa-kepler-mission-discovers-bigger-older-cousin-to-earth/|url-status=live}}</ref> However, it is unknown if it is entirely habitable, as it is receiving slightly more energy from its star than Earth and could be subjected to a [[runaway greenhouse effect]].
-The exoplanet was identified by the [[Kepler (spacecraft)|''Kepler'']] [[space telescope]], and its discovery was announced by [[NASA]] on 23 July 2015.<ref name=Jenkins2015>{{cite journal| last1=Jenkins| first1=Jon M.| last2=Twicken| first2=Joseph D.| last3=Batalha|first3=Natalie M.| last4=Caldwell| first4=Douglas A.| last5=Cochran| first5=William D.| last6=Endl| first6=Michael| last7=Latham| first7=David W.| last8=Esquerdo| first8=Gilbert A.|last9=Seader|first9=Shawn|last10=Bieryla|first10=Allyson|last11=Petigura|first11=Erik|last12=Ciardi|first12=David R.|last13=Marcy|first13=Geoffrey W.|last14=Isaacson|first14=Howard|last15=Huber|first15=Daniel|last16=Rowe|first16=Jason F.|last17=Torres|first17=Guillermo|last18=Bryson|first18=Stephen T.|last19=Buchhave|first19=Lars|last20=Ramirez|first20=Ivan|last21=Wolfgang|first21=Angie|last22=Li|first22=Jie|last23=Campbell|first23=Jennifer R.|last24=Tenenbaum|first24=Peter|last25=Sanderfer|first25=Dwight|last26=Henze|first26=Christopher E.|last27=Catanzarite|first27=Joseph H.|last28=Gilliland|first28=Ronald L.|last29=Borucki|first29=William J.|display-authors=3| title=Discovery and Validation of Kepler-452b: A 1.6 R⨁ Super Earth Exoplanet in the Habitable Zone of a G2 Star| journal=The Astronomical Journal| date=23 July 2015| volume=150| issue=2| page=56| issn=1538-3881|doi=10.1088/0004-6256/150/2/56| url=http://www.nasa.gov/sites/default/files/atoms/files/ms-r1b.pdf|access-date=24 July 2015|arxiv = 1507.06723 |bibcode = 2015AJ....150...56J | s2cid=26447864}}</ref> The planet is about 1,800 light-years away from the [[Solar System]]. At the speed of the ''[[New Horizons]]'' [[spacecraft]], about {{convert|59,000|km/h|mph|abbr=on}}, it would take approximately 30 million years to get there.<ref name="bno">{{cite web |url=http://bnonews.com/news/index.php/news/id961 |title=NASA telescope discovers Earth-like planet in star's 'habitable zone |date=23 July 2015 |work=[[BNO News]] |access-date=23 July 2015}}</ref>
+The Kepler [[space telescope]] identified the exoplanet, and its discovery was announced by [[NASA]] on 23 July 2015.<ref name=Jenkins2015>{{cite journal|last1=Jenkins|first1=Jon M.|last2=Twicken|first2=Joseph D.|last3=Batalha|first3=Natalie M.|last4=Caldwell|first4=Douglas A.|last5=Cochran|first5=William D.|last6=Endl|first6=Michael|last7=Latham|first7=David W.|last8=Esquerdo|first8=Gilbert A.|last9=Seader|first9=Shawn|last10=Bieryla|first10=Allyson|last11=Petigura|first11=Erik|last12=Ciardi|first12=David R.|last13=Marcy|first13=Geoffrey W.|last14=Isaacson|first14=Howard|last15=Huber|first15=Daniel|last16=Rowe|first16=Jason F.|last17=Torres|first17=Guillermo|last18=Bryson|first18=Stephen T.|last19=Buchhave|first19=Lars|last20=Ramirez|first20=Ivan|last21=Wolfgang|first21=Angie|last22=Li|first22=Jie|last23=Campbell|first23=Jennifer R.|last24=Tenenbaum|first24=Peter|last25=Sanderfer|first25=Dwight|last26=Henze|first26=Christopher E.|last27=Catanzarite|first27=Joseph H.|last28=Gilliland|first28=Ronald L.|last29=Borucki|first29=William J.|display-authors=3|title=Discovery and Validation of Kepler-452b: A 1.6 R<sub>🜨</sub> Super Earth Exoplanet in the Habitable Zone of a G2 Star|journal=The Astronomical Journal|date=23 July 2015|volume=150|issue=2|page=56|issn=1538-3881|doi=10.1088/0004-6256/150/2/56|url=http://www.nasa.gov/sites/default/files/atoms/files/ms-r1b.pdf|access-date=24 July 2015|arxiv=1507.06723|bibcode=2015AJ....150...56J|s2cid=26447864|archive-date=5 July 2016|archive-url=https://web.archive.org/web/20160705184651/http://www.nasa.gov/sites/default/files/atoms/files/ms-r1b.pdf|url-status=live}}</ref> The planet is about {{convert|1,800|ly|pc}} away from the [[Solar System]]. At the speed of the ''[[New Horizons]]'' [[spacecraft]], at about {{convert|59,000|km/h|m/s mph|abbr=on}}, it would take approximately 30 million years to get there.<ref name="bno">{{cite web |url=http://bnonews.com/news/index.php/news/id961 |title=NASA telescope discovers Earth-like planet in star's 'habitable zone |date=23 July 2015 |work=[[BNO News]] |access-date=23 July 2015 |archive-date=4 March 2016 |archive-url=https://web.archive.org/web/20160304042706/http://bnonews.com/news/index.php/news/id961 |url-status=dead }}</ref>
 ==Physical characteristics==
 ===Mass, radius and temperature===
-[[File:Kepler-452b versus Earth.jpg|thumb|450px|Size of Kepler-452b versus Earth size]]
+[[File:Kepler-452b and Earth Size.jpg|thumb|300px|Size comparison between Kepler-452b ''(right)'' and Earth ''(left)'', along with the similarities of their parent stars.]]
-Kepler-452b has a probable mass five times that of Earth, and its surface gravity is nearly twice as Earth's, though calculations of mass for exoplanets are only rough estimates.<ref name=Feltman /> 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.
+Kepler-452b has a probable mass five times that of Earth, and its surface gravity is nearly twice as much as Earth's, though calculations of mass for exoplanets are only rough estimates.<ref name=Feltman /> 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.
-The planet takes 385 Earth days to orbit its star.<ref name=Overbye>{{cite news|last1=Overbye|first1=Dennis|title=Kepler Data Reveals What Might Be Best 'Goldilocks' Planet Yet|url=https://www.nytimes.com/2015/07/24/science/space/kepler-data-reveals-what-might-be-best-goldilocks-planet-yet.html|access-date=23 July 2015|work=[[The New York Times]]|date=23 July 2015}}</ref> Its radius is 50% bigger than [[Earth]]'s, and lies within the conservative [[Circumstellar habitable zone|habitable zone]] of its parent star.<ref name=Feltman>{{cite news|last1=Feltman|first1=Rachel|title=Scientists discover 12 new potential Earth-like planets|url=https://www.washingtonpost.com/news/speaking-of-science/wp/2015/07/23/scientists-discover-12-new-potential-earth-like-planets/|access-date=23 July 2015|work=[[The Washington Post]]|date=23 July 2015}}</ref><ref name=Witze>{{cite news|last1=Witze|first1=Alexandra|title=NASA spies Earth-sized exoplanet orbiting Sun-like star|url=http://www.nature.com/news/nasa-spies-earth-sized-exoplanet-orbiting-sun-like-star-1.18048|access-date=23 July 2015|work=Nature|date=23 July 2015}}</ref> It has an equilibrium temperature of {{convert|265|K|C F}}, a little warmer than Earth.
+The planet takes 385 Earth days to orbit its star.<ref name=Overbye>{{cite news|last1=Overbye|first1=Dennis|title=Kepler Data Reveals What Might Be Best 'Goldilocks' Planet Yet|url=https://www.nytimes.com/2015/07/24/science/space/kepler-data-reveals-what-might-be-best-goldilocks-planet-yet.html|access-date=23 July 2015|work=[[The New York Times]]|date=24 July 2015|archive-date=24 July 2015|archive-url=https://web.archive.org/web/20150724153629/http://www.nytimes.com/2015/07/24/science/space/kepler-data-reveals-what-might-be-best-goldilocks-planet-yet.html|url-status=live}}</ref> Its radius is 50% larger than [[Earth]]'s, and lies within the conservative [[Circumstellar habitable zone|habitable zone]] of its parent star.<ref name=Feltman>{{cite news|last1=Feltman|first1=Rachel|title=Scientists discover 12 new potential Earth-like planets|url=https://www.washingtonpost.com/news/speaking-of-science/wp/2015/07/23/scientists-discover-12-new-potential-earth-like-planets/|access-date=23 July 2015|newspaper=[[The Washington Post]]|date=23 July 2015|archive-date=18 July 2020|archive-url=https://web.archive.org/web/20200718001218/https://www.washingtonpost.com/news/speaking-of-science/wp/2015/07/23/scientists-discover-12-new-potential-earth-like-planets/|url-status=live}}</ref><ref name=Witze>{{cite news|last1=Witze|first1=Alexandra|title=NASA spies Earth-sized exoplanet orbiting Sun-like star|url=http://www.nature.com/news/nasa-spies-earth-sized-exoplanet-orbiting-sun-like-star-1.18048|access-date=23 July 2015|work=Nature|date=23 July 2015|archive-date=23 November 2019|archive-url=https://web.archive.org/web/20191123084429/http://www.nature.com/news/nasa-spies-earth-sized-exoplanet-orbiting-sun-like-star-1.18048|url-status=live}}</ref> It has an [[equilibrium temperature]] of {{convert|265|K|C F}}, a little warmer than Earth.
 ===Host star===
 {{main|Kepler-452}}
-The host star, [[Kepler-452]], is a [[Stellar classification#Class G|G-type]] and has about the same mass as the sun, only 3.7% more massive and 11% larger. It has a surface temperature of 5757 [[Kelvin|K]], nearly the same as the Sun, which has a surface temperature of 5778 K.<ref>{{cite web|url=http://www.universetoday.com/18092/temperature-of-the-sun/ |title=Temperature of the Sun|author=Fraser Cain |date=15 September 2008 |publisher=[[Universe Today]] |access-date=19 February 2011}}</ref> The star's age is estimated to be about 6 billion years old, about 1.5 billion years older than the Sun, which is 4.6 billion years old. From the surface of Kepler-452b, its star would look almost identical to the [[Sun]] as viewed from the Earth.<ref>NASA Kepler press conference. 23 July 2015.</ref>
+The host star, [[Kepler-452]], is a [[Stellar classification#Class G|G-type]] and has about the same mass as the sun, only 3.7% more massive and 11% larger. It has a surface temperature of 5757 [[Kelvin|K]], nearly the same as the Sun, which has a surface temperature of 5778 K.<ref>{{cite web |url=http://www.universetoday.com/18092/temperature-of-the-sun/ |title=Temperature of the Sun |author=Fraser Cain |date=15 September 2008 |publisher=[[Universe Today]] |access-date=19 February 2011 |archive-date=29 August 2010 |archive-url=https://web.archive.org/web/20100829025937/http://www.universetoday.com/18092/temperature-of-the-sun/ |url-status=live }}</ref> The star's age is estimated to be about 6 billion years old, about 1.5 billion years older than the Sun, which is estimated to have existed for 4.6 billion years. Kepler-452b has been in Kepler-452's habitable zone for most of its existence, a duration just over six billion years.<ref name=":022">{{Cite book |last1=Bohan |first1=Elise |url=https://www.worldcat.org/oclc/940282526 |title=Big History |last2=Dinwiddie |first2=Robert |last3=Challoner |first3=Jack |last4=Stuart |first4=Colin |last5=Harvey |first5=Derek |last6=Wragg-Sykes |first6=Rebecca |last7=Chrisp |first7=Peter |last8=Hubbard |first8=Ben |last9=Parker |first9=Phillip |collaboration=Writers |date=February 2016 |publisher=[[DK (publisher)|DK]] |others=Foreword by [[David Christian (historian)|David Christian]] |isbn=978-1-4654-5443-0 |edition=1st American |location=[[New York City|New York]] |pages=77 |oclc=940282526 |author-link6=Rebecca Wragg Sykes |author-link7=Peter Chrisp |access-date=18 March 2023 |archive-date=8 September 2024 |archive-url=https://web.archive.org/web/20240908120327/https://search.worldcat.org/title/940282526 |url-status=live }}</ref>
-The star's [[apparent magnitude]], or how bright it appears from Earth's perspective, is 13.426; therefore, it is too dim to be seen with the naked eye.
+From the surface of Kepler-452b, its star would look almost identical to the [[Sun]] as viewed from the Earth.<ref>NASA Kepler press conference. 23 July 2015.</ref> The star's [[apparent magnitude]], or how bright it appears from Earth's perspective, is 13.426; therefore, it is too dim to be seen with the naked eye.
 ===Orbit===
@@ Line 51: / Line 50: @@
 ==Potential habitability==
 [[File:Kepler452b-Earth-SurfaceTemp-vs-Energy-20150723.gif|thumb|left|275px|Comparison of Kepler-452b and related exoplanets with Earth.]]
-It is not known if Kepler-452b is a [[Terrestrial planet|rocky planet]]<ref name="RinconP2015" /> but based on its small radius, Kepler-452b is likely to be rocky.<ref name=Jenkins2015 /> It is not clear if Kepler-452b offers habitable environments. It orbits a G2V-type star, like the Sun, which is  20% more luminous, with nearly the same temperature and mass.<ref name=Overbye /> However, the star is 6 billion years old, making it 1.5 billion years older than the Sun. At this point in its star's [[stellar evolution|evolution]], Kepler-452b is currently receiving 10% more energy from its parent star than Earth is currently receiving from the Sun.<ref name=Chou /> If Kepler-452b is a rocky planet, it may be subject to a [[runaway greenhouse effect]] similar to that seen on [[Venus]].<ref name=Lugmayr>{{cite news|last1=Lugmayr|first1=Luigi|title=Kepler-452b details unveiled|url=http://www.i4u.com/2015/07/93538/kepler-452b-details-unveiled|access-date=23 July 2015|agency=I4U News|date=23 July 2015}}</ref>
+It is not known if Kepler-452b is a [[Terrestrial planet|rocky planet]]<ref name="RinconP2015" /> but based on its small radius, Kepler-452b is likely to be rocky.<ref name=Jenkins2015 /> It is not clear if Kepler-452b offers habitable environments. It orbits a G2V-type star, like the Sun, which is 20% more luminous, with nearly the same temperature and mass.<ref name=Overbye/> However, the star is roughly 6 billion years old, making it 1.5 billion years older than the Sun. At this point in its star's [[stellar evolution|evolution]], Kepler-452b is currently receiving 10% more energy from its parent star than Earth is currently receiving from the Sun.<ref name=Chou /> If Kepler-452b is a rocky planet, it may be subject to a [[runaway greenhouse effect]] similar to that seen on [[Venus]].<ref name=Lugmayr>{{cite news|last1=Lugmayr|first1=Luigi|title=Kepler-452b details unveiled|url=http://www.i4u.com/2015/07/93538/kepler-452b-details-unveiled|access-date=23 July 2015|agency=I4U News|date=23 July 2015|archive-date=9 October 2019|archive-url=https://web.archive.org/web/20191009124433/https://www.i4u.com/2015/07/93538/kepler-452b-details-unveiled|url-status=live}}</ref>
-==="Delayed" runaway greenhouse===
+==="Delayed" runaway greenhouse effect===
-However, due to the planet Kepler 452b being 50 percent bigger in terms of size, it is likely to have an estimated mass of 5 {{earth mass}}, which could allow it to hold on to any oceans it may have for a longer period, preventing Kepler-452b from succumbing to [[Future of the Earth#Loss of oceans|runaway greenhouse effect]] for another 500 million years.<ref name=Lugmayr/> This, in turn, would be accompanied with the [[carbonate–silicate cycle]] being "buffered" extending its lifetime due to increased volcanic activity on Kepler-452b.<ref name=Kep452bAdvancedEarth2.0>{{cite web|url=https://gizmodo.com/is-earths-closest-cousin-a-dying-planet-1720434455|title=Is Earth's Closest Cousin A Dying Planet?|work=Gizmodo.com|date=30 July 2015|access-date=24 May 2016}}</ref> This could allow any potential life on the surface to inhabit the planet for another 500–900 million years before the habitable zone is pushed beyond Kepler-452b's orbit.
+However, due to the planet Kepler-452b being 50 percent bigger in terms of size, it is likely to have an estimated mass of 5 {{Earth mass}}, which could allow it to hold on to any oceans it may have for a longer period, preventing Kepler-452b from succumbing to [[Future of the Earth#Loss of oceans|runaway greenhouse effect]] for another 500 million years.<ref name=Lugmayr/> This, in turn, would be accompanied by the [[carbonate–silicate cycle]] being "buffered", extending its lifetime due to increased volcanic activity on Kepler-452b.<ref name=Kep452bAdvancedEarth2.0>{{cite web|url=https://gizmodo.com/is-earths-closest-cousin-a-dying-planet-1720434455|title=Is Earth's Closest Cousin A Dying Planet?|work=Gizmodo.com|date=30 July 2015|access-date=24 May 2016|archive-date=19 May 2016|archive-url=https://web.archive.org/web/20160519094635/http://gizmodo.com/is-earths-closest-cousin-a-dying-planet-1720434455|url-status=live}}</ref> This could allow any potential life on the surface to inhabit the planet for another 500–900 million years before the habitable zone is pushed beyond Kepler-452b's orbit.
 ==Discovery and follow-up studies==
-In 2009, [[NASA]]'s [[Kepler (spacecraft)|Kepler]] spacecraft was observing stars on its [[photometer]], the instrument it uses to detect [[transit method|transit]] events, in which a planet crosses in front of and dims its host star for a brief and roughly regular time. In this last test, Kepler observed {{val|50,000}} stars in the [[Kepler Input Catalog]], including Kepler-452; the preliminary light curves were sent to the Kepler science team for analysis, who chose obvious planetary companions from the bunch for follow-up by other telescopes. Observations for the potential exoplanet candidates took place between 13 May 2009 and 17 March 2012. Kepler-452b exhibited a transit which occurred roughly every 385 days, and it was eventually concluded that a planetary body was responsible. The discovery was announced by NASA on 23 July 2015.<ref name=Jenkins2015/>
+In 2009, [[NASA]]'s [[Kepler space telescope]] was observing stars on its [[photometer]], the instrument it uses to detect [[transit method|transit]] events, in which a planet crosses in front of and dims its host star for a brief and roughly regular time. In this last test, Kepler observed {{val|50,000}} stars in the [[Kepler Input Catalog]], including Kepler-452; the preliminary light curves were sent to the Kepler science team for analysis, who chose obvious planetary companions from the bunch for follow-up by other telescopes. Observations for the potential exoplanet candidates took place between 13 May 2009 and 17 March 2012. Kepler-452b exhibited a transit that occurred roughly every 385 days, and it was eventually concluded that a planetary body was responsible. The discovery was announced by NASA on 23 July 2015.<ref name=Jenkins2015/>
-At a distance of nearly {{convert|430|pc|ly|disp=flip}}, Kepler-452b is too remote for current telescopes or the next generation of planned telescopes to determine its true mass or whether it has an atmosphere. The Kepler spacecraft focused on a single small region of the sky but next-generation planet-hunting space telescopes, such as [[Transiting Exoplanet Survey Satellite|TESS]] and [[CHEOPS]], will examine nearby stars throughout the sky with follow up studies planned for these closer exoplanets by the upcoming [[James Webb Space Telescope]] and future large ground-based telescopes to analyze their atmospheres, determine masses and infer compositions.
+At a distance of nearly {{convert|550|pc|ly|disp=flip}}, Kepler-452b is too remote for current telescopes or the next generation of planned telescopes to determine its true mass or whether it has an atmosphere. The Kepler space telescope focused on a single small region of the sky but next-generation planet-hunting space telescopes, such as [[Transiting Exoplanet Survey Satellite|TESS]] and [[CHEOPS]], will examine nearby stars throughout the sky with follow up studies planned for these closer exoplanets by the [[James Webb Space Telescope]] and future large ground-based telescopes to analyze their atmospheres, determine masses, and infer compositions.
-A study in 2018 by Mullally et al. claimed that statistically, Kepler-452b has not been proven to exist and must still be considered a candidate.<ref>''Kepler's Earth-like Planets Should Not Be Confirmed without Independent Detection: The Case Of Kepler-452b'' Fergal Mullally, Susan E. Thompson, Jeffrey L. Coughlin, Christopher J. Burke, and Jason F. Rowe, 2 April 2018. Available at {{ArXiv|1803.11307}}, Accessed 3 April 2018.</ref>
+A study in 2018 by Mullally et al. claimed that statistically, Kepler-452b has not been proven to exist and must still be considered a candidate.<ref name="Mullally2018"/> However, Kepler-452b is still a possible planet and has not been shown to be a false positive.<ref name="Mullally2018"/>
 ===SETI targeting===
-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.<ref name="space.com">[http://www.space.com/30114-seti-alien-life-kepler-452b-earth-cousin.html SETI Targets Kepler-452b, Earth's 'Cousin,' in Search for Alien Life]</ref> SETI Institute researchers are using the [[Allen Telescope Array]], a collection of 6-meter (20 feet) telescopes in the [[Cascade Range|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.<ref name="space.com" />
+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.<ref name="space.com">{{Cite web |url=http://www.space.com/30114-seti-alien-life-kepler-452b-earth-cousin.html |title=SETI Targets Kepler-452b, Earth's 'Cousin,' in Search for Alien Life |website=[[Space.com]] |date=31 July 2015 |access-date=9 January 2016 |archive-date=20 July 2020 |archive-url=https://web.archive.org/web/20200720210221/https://www.space.com/30114-seti-alien-life-kepler-452b-earth-cousin.html |url-status=live }}</ref> SETI Institute researchers are using the [[Allen Telescope Array]], a collection of 6-meter (20 feet) telescopes in the [[Cascade Range|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 analysis.<ref name="space.com" />
 ==Observation and exploration==
-Kepler-452b is {{convert|1400|ly|m AU mi|abbr=off}} from Earth. The fastest current spacecraft, the [[New Horizons]] unmanned probe that passed [[Pluto]] in July 2015, travels at just {{convert|56628|km/h|mph+AU/h|abbr=on}}.<ref name="express.co.uk" /> At that speed, it would take a spacecraft about 26 million years to reach Kepler-452b from Earth, if it was going in that direction.<ref name="express.co.uk" />
+Kepler-452b is {{convert|1,800|ly|pc|abbr=off}} from Earth. The fastest current spacecraft, the ''[[New Horizons]]'' uncrewed probe that passed [[Pluto]] in July 2015, travels at just {{convert|56,628|km/h|m/s mph AU/h|abbr=on}}.<ref name="express.co.uk" /> At that speed, it would take a spacecraft about 26 million years to reach Kepler-452b from Earth, if it were going in that direction.<ref name="express.co.uk" />
 {| class="wikitable" style="margin:0.5em auto; width:450px; align=right"
@@ Line 73: / Line 72: @@
 |-
 | style="font-size:88%" | [[File:PIA19827-Kepler-SmallPlanets-HabitableZone-20150723.jpg|600px]]
-<center>Comparison of small planets found by ''[[Kepler (spacecraft)|Kepler]]'' in the [[habitable zone]] of their host stars.</center>
+{{center|Comparison of small planets found by ''[[Kepler (spacecraft)|Kepler]]'' in the [[habitable zone]] of their host stars.}}
 |}
 ==Gallery==
 {{Gallery |align=center |width=450
-|File:Kepler-452b System.jpg|{{small|<center>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.</center>}}
+|File:Kepler-452b System.jpg|{{center|{{small|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.}}}}
-|File:Kepler-452b and Earth Size.jpg|{{small|<center>This artist's concept compares Earth (left) to Kepler-452b, which is about 50% larger in diameter.</center>}}
 |title=}}
@@ Line 85: / Line 83: @@
 * [[List of largest exoplanets]]
 * [[List of potentially habitable exoplanets]]
+* [[Superhabitable world]]
 ==References==
 {{Reflist|refs=
+<ref name="Mullally2018">{{cite journal |last1=Mullally |first1=Fergal |last2=Thompson |first2=Susan E. |last3=Coughlin |first3=Jeffrey L. |last4=Burke |first4=Christopher J. |last5=Rowe |first5=Jason F. |date=May 2018 |title=Kepler's Earth-like Planets Should Not Be Confirmed without Independent Detection: The Case of Kepler-452b |journal=[[The Astronomical Journal]] |volume=155 |issue=5 |pages=210 |doi=10.3847/1538-3881/aabae3 |doi-access=free |arxiv=1803.11307 |bibcode=2018AJ....155..210M}}</ref>
+<ref name="Burke2019">{{cite journal |last1=Burke |first1=Christopher J. |last2=Mullally |first2=F. |last3=Thompson |first3=Susan E. |last4=Coughlin |first4=Jeffrey L. |last5=Rowe |first5=Jason F. |date=April 2019 |title=Re-evaluating Small Long-period Confirmed Planets from Kepler |journal=[[The Astronomical Journal]] |volume=157 |issue=4 |pages=143 |doi=10.3847/1538-3881/aafb79 |doi-access=free |arxiv=1901.00506 |bibcode=2019AJ....157..143B}}</ref>
 }}
 ==External links==
-{{Commons category|Kepler-452b}}
+{{Commons category|Kepler-452 b}}
 * [https://www.nasa.gov/mission_pages/kepler/overview/index.html NASA – Mission overview]
 * [https://web.archive.org/web/20100527104316/http://kepler.nasa.gov/Mission/discoveries/ NASA – Kepler Discoveries – Summary Table]
 * [http://phl.upr.edu/projects/habitable-exoplanets-catalog Habitable Exoplanets Catalog] at [[University of Puerto Rico at Arecibo|UPR-Arecibo]].
-* [http://www.nasa.gov/sites/default/files/atoms/files/ms-r1b.pdf Discovery and Validation of Kepler-452b: A 1.6 R⨁ Super-Earth Exoplanet in the Habitable Zone of a G2 Star]
+* [http://www.nasa.gov/sites/default/files/atoms/files/ms-r1b.pdf Discovery and Validation of Kepler-452b: A 1.6-R<sub>🜨</sub> Super-Earth Exoplanet in the Habitable Zone of a G2 Star]
 {{Exoplanet}}