View source for Kepler-90i

{{Short description|Super-Earth orbiting Kepler-90}}
{{Use dmy dates|date=December 2017}}
{{Infobox planet
| name = Kepler-90i
| image = Kepler-90 MultiExoplanet System - 20171214.jpg
| caption = Illustration of the Kepler-90 system compared to the inner solar system. Kepler-90h is the outermost planet of the Kepler-90 system.
| discoverer = ''[[Kepler (spacecraft)|Kepler]]'' spacecraft<ref name="Harvard-20171216" />
| discovered = 2017 Shallue et al.<ref name="NASAExoplanet">{{cite web|url=http://exoplanetarchive.ipac.caltech.edu/cgi-bin/DisplayOverview/nph-DisplayOverview?objname=Kepler-90+i|title=Kepler-90 i|work=NASA Exoplanet Archive|access-date=14 December 2017}}</ref><ref name="Harvard-20171216">{{cite news |last1=Shallue |first1=Christopher J. |last2=Vanderburg |first2=Andrew |title=Identifying Exoplanets With Deep Learning: A Five Planet Resonant Chain Around Kepler-80 And An Eighth Planet Around Kepler-90 |url=https://www.cfa.harvard.edu/~avanderb/kepler90i.pdf |date=16 December 2017 |access-date=14 December 2017}}</ref>
| discovery_method = [[Transit method|Transit]]<ref name="NASAExoplanet" /> and [[deep learning]], a class of [[machine learning algorithms]].<ref name="Harvard-20171216" />
| apsis = astron
| semimajor = 0.107{{±|0.025|0.040}}<ref name="Harvard-20171216" /> [[astronomical unit|AU]]
| period = 14.44912±0.00020<ref name="NASAExoplanet" /> [[day|d]]
| inclination = 89.20 {{±|0.59|1.30}}<ref name="NASAExoplanet" />
| star = [[Kepler-90]]
| mean_radius = 1.32±0.21<ref name="NASAExoplanet" /> {{Earth radius|link=y}}
| single_temperature = {{convert|709|K|C F}}<ref name="NASAExoplanet" />
}}
'''Kepler-90i'''  (also known by its Kepler Object of Interest designation KOI-351.08)<ref name="NASAExoplanet" /> is a [[super-Earth]] [[exoplanet]] with a radius 1.32<ref name="NASAExoplanet" />  times that of Earth, orbiting the early [[G-type main sequence star]] [[Kepler-90]] every 14.45 days, discovered by [[NASA]]'s [[Kepler (spacecraft)|Kepler spacecraft]].<ref name="Harvard-20171216" /><ref name="NYT-20171214">{{cite news |last=St. Fleur |first=Nicholas |title=An 8th Planet Is Found Orbiting a Distant Star, With A.I.'s Help |url=https://www.nytimes.com/2017/12/14/science/eight-planets-star-system.html |date=14 December 2017 |work=[[The New York Times]] |access-date=15 December 2017 }}</ref> It is located about 2,840 [[light-year]]s (870 [[parsec]]s, or nearly {{val|2.4078|e=16}} [[km]]) from Earth in the constellation [[Draco (constellation)|Draco]]. The exoplanet is the eighth in the star's multiplanetary system. As of December 2017, Kepler-90 is the star hosting the most exoplanets found. Kepler-90i was found with the [[transit method]], in which the dimming effect that a planet causes as it crosses in front of its star is measured, and by a newly utilized computer tool, [[deep learning]], a class of [[machine learning algorithms]].<ref name="Harvard-20171216" /><ref name="NASA-20171214">{{cite web |last1=Chou |first1=Felecia |last2=Hawkes |first2=Alison |last3=Northon |first3=Karen|title=Release 17-098 – Artificial Intelligence, NASA Data Used to Discover Eighth Planet Circling Distant Star |url=https://www.nasa.gov/press-release/artificial-intelligence-nasa-data-used-to-discover-eighth-planet-circling-distant-star |date=14 December 2017 |work=[[NASA]] |access-date=14 December 2017 }}</ref><ref name="NASA-20171214a">{{cite web |last1=Chou |first1=Felicia |last2=Hawkes |first2=Alison |last3=Landau |first3=Elizabeth |title=Artificial Intelligence, NASA Data Used to Discover Eighth Planet Circling Distant Star |url=https://www.jpl.nasa.gov/news/news.php?feature=7026 |date=14 December 2017 |work=[[NASA]] |access-date=15 December 2017 }}</ref>

==Characteristics==
===Mass, radius and temperature===
Kepler-90i is a [[super-Earth]] [[exoplanet]] with a radius of 1.32 {{earth radius|link=y}},<ref name="NASAExoplanet" /> indicating that it is small enough to be [[Terrestrial planet|rocky]]. With an Earth-like composition, Kepler-90i would have a mass of about 2.3 {{earth mass|link=y}}, since its volume is <math>1.32^3 \approx 2.3</math> times that of Earth's. It has an equilibrium temperature of {{convert|709|K|C F}}, similar to the average temperature of [[Venus]].

===Host star===
{{main|Kepler-90}}
The planet orbits [[Kepler-90]], a [[Stellar classification#Class G|G-type]] [[main sequence]] [[star]]. The star has a mass of 1.2 {{Solar mass}} and a radius 1.2 {{Solar radius}}. It has a surface temperatures of 6080 [[Kelvin|K]] and has an estimated age of around 2 billion years, with considerable uncertainty. In comparison, the Sun is about 4.6 billion years old<ref name="UT-20080916">{{cite web |last=Cain |first=Fraser |title=How Old is the Sun? |url=http://www.universetoday.com/18237/how-old-is-the-sun/ |date=16 September 2008 |work=[[Universe Today]] |access-date=14 December 2017}}</ref> and has a surface temperature of 5778 K.<ref name="UT-20080915">{{cite web |last=Cain |first=Fraser |title=Temperature of the Sun |url=http://www.universetoday.com/18092/temperature-of-the-sun/|date=15 September 2008 |work=[[Universe Today]] |access-date=14 December 2017}}</ref>

The star's [[apparent magnitude]], or how bright it appears from Earth's perspective, is 14. It is too dim to be seen with the naked eye.

===Orbital characteristics===
Kepler-90i orbits its host star about every 14.45 days with a semi-major axis of 0.107 [[Astronomical unit|AU]].

Due to its very close distance to its host star, it is likely to be [[Tidal locking|tidally locked]], meaning that one side permanently faces the star in eternal daylight and the other side permanently faces away from the star in eternal darkness.

==Discovery==
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 period of time. In its last test, ''Kepler'' observed {{val|50,000}} stars in the [[Kepler Input Catalog]], including [[Kepler-90]]; the preliminary light curves were sent to the ''Kepler'' science team for analysis, who chose obvious planetary companions from the bunch for follow-up at observatories. Discovery of the exoplanet was aided by a newly utilized computer tool, [[deep learning]], a class of [[machine learning algorithms]].<ref name="Harvard-20171216" /><ref name="NASA-20171214" />
<!---[[File:17-098-Kepler-90 MultiExoplanetSystem-20171214.jpg|thumb|center|600px|{{center|The 8 planets of Kepler-90. Kepler-90i is the third planet from the star. (14 December 2017)}}]]--->
[[File:Kepler-90 system rightward-PIA22193.jpg|thumb|center|600px|{{center|Artist's impression of the planets of the Kepler-90 exoplanetary system compared to the eight planets of the Solar System.}}]]

==See also==
* [[Kepler-80]]g

==References==
{{reflist|refs=
}}

{{Sky|18|57|44.04|+|49|18|18.6}}
{{Kepler-90}}
{{2017 in space}}
{{Exoplanets}}
{{Stars of Draco}}
{{Portal bar|Astronomy|Space}}

{{DEFAULTSORT:Kepler-90i}}
[[Category:Exoplanets discovered by the Kepler space telescope]]
[[Category:Exoplanets discovered in 2017]]
[[Category:Transiting exoplanets]]
[[Category:Draco (constellation)]]