Encyclopedia/1. The Cosmos & The Natural World/3. Astronomy & Planetary Science • Curated by Admin Timeline.sg
The search for exoplanets and astrobiology explores worlds beyond our solar system, from the first confirmed detection in 1995 to the latest biosignature studies with JWST, revolutionizing our understanding of planetary systems and the potential for life.
Chronological Storyline (44 Milestones)
350 BCE
Aristotle's Geocentric Model
Aristotle proposes a geocentric universe with Earth at the center, influencing Western thought for centuries. #astronomy #history
Aristotle's Geocentric Model By Bartolomeu Velho - Own work, Public domain, https://commons.wikimedia.org/w/index.php?curid=3672259
1543 CE
Copernicus Proposes Heliocentrism
Nicolaus Copernicus publishes 'De revolutionibus orbium coelestium,' placing the Sun at the center of the solar system. #astronomy #science
Copernicus Proposes Heliocentrism By Unknown author - http://www.frombork.art.pl/Ang10.htm https://www.welt.de/img/kultur/mobile152954235/1212503297-ci102l-w1024/Kopernikus-Gemaelde-in-Krakau.jpg https://muzeum.torun.pl/wp-content/uploads/2023/03/Portert-Mikolaja-Kopernika-MOT.jpg, Public domain, https://commons.wikimedia.org/w/index.php?curid=147956893
1609 CE
Galileo Observes Jupiter's Moons
Galileo Galilei discovers four moons orbiting Jupiter, providing evidence that not all celestial bodies orbit Earth. #astronomy #discovery
Galileo Observes Jupiter's Moons By WhatADrag07 - https://photojournal.jpl.nasa.gov/catalog/PIA00600, https://science.nasa.gov/resource/global-image-of-io-true-color/, https://www.flickr.com/photos/kevinmgill/53255790801, https://www.flickr.com/photos/kevinmgill/51238659798/, https://www.flickr.com/photos/kevinmgill/38926064465/, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=175775037
1687 CE
Newton's Law of Universal Gravitation
Isaac Newton publishes 'Philosophiæ Naturalis Principia Mathematica,' describing gravity and planetary motion. #physics #astronomy
Mar 13, 1781 CE
Discovery of Uranus
William Herschel discovers Uranus, the first planet found with a telescope, expanding the known solar system. #astronomy #discovery
Discovery of Uranus By Ardenau4 - Own workalso published on Flickr: https://www.flickr.com/photos/197038812@N04/53449450202/, CC0, https://commons.wikimedia.org/w/index.php?curid=143666922
Sep 23, 1846 CE
Discovery of Neptune
Johann Galle discovers Neptune based on mathematical predictions by Urbain Le Verrier, demonstrating the power of celestial mechanics. #astronomy #science
Discovery of Neptune By NASA / Voyager 2 / PDS / OPUS / Ardenau4 - Own workalso published on Flickr: https://www.flickr.com/photos/197038812@N04/53446862462/, CC0, https://commons.wikimedia.org/w/index.php?curid=143615671
1915 CE
Einstein's General Relativity
Albert Einstein publishes general relativity, describing gravity as spacetime curvature and enabling new insights into planetary orbits. #physics #science
Einstein's General Relativity By Simulating eXtreme Spacetimes Lensing (SXS) - https://www.ligo.caltech.edu/video/ligo20160211v3 (video link); see also http://www.black-holes.org/gw150914, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=46994894
1952 CE
First Exoplanet Claim: Barnard's Star
Peter van de Kamp claims detection of a planet around Barnard's Star using astrometry, later disproven. #exoplanets #astronomy
First Exoplanet Claim: Barnard's Star By Steve Quirk - https://web.archive.org/web/20080721013827/http://my.hwy.com.au/~sjquirk/images/film/barnard.html, Public domain, https://commons.wikimedia.org/w/index.php?curid=3160016
1963 CE
Discovery of Quasars
Maarten Schmidt identifies quasars as distant active galactic nuclei, expanding the known universe. #astronomy #cosmology
Discovery of Quasars By ESO/M. Kornmesser - http://www.eso.org/public/images/eso1122a/, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=15700804
Jan 9, 1992 CE
First Confirmed Exoplanets: Pulsar Planets
Aleksander Wolszczan and Dale Frail announce the discovery of two planets orbiting the pulsar PSR B1257+12, the first confirmed exoplanets. #exoplanets #astronomy
Oct 6, 1995 CE
51 Pegasi b: First Exoplanet Around Sun-like Star
Michel Mayor and Didier Queloz announce the discovery of 51 Pegasi b, a hot Jupiter orbiting a Sun-like star, revolutionizing exoplanet science. #exoplanets #astronomy
51 Pegasi b: First Exoplanet Around Sun-like Star By ESO/M. Kornmesser/Nick Risinger (skysurvey.org) - ESO website, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=39719418
1996 CE
First Exoplanet in Multiple Planet System: Upsilon Andromedae
Discovery of multiple planets around Upsilon Andromedae, revealing that exoplanetary systems can have complex architectures. #exoplanets #astronomy
First Exoplanet in Multiple Planet System: Upsilon Andromedae By Andromeda_constellation_map.png: Torsten Bronger derivative work: Kxx (talk) - Andromeda_constellation_map.png, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=10826751
Nov 15, 1999 CE
First Transiting Exoplanet: HD 209458 b
HD 209458 b becomes the first exoplanet detected via the transit method, allowing measurement of its size and atmosphere. #exoplanets #astronomy
First Transiting Exoplanet: HD 209458 b By Aldaron, a.k.a. Aldaron - Own work, incorporating public domain images for reference planets (see below), inspired by Thingg's size comparison, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=8903868
2001 CE
First Exoplanet Atmosphere Detected
Sodium absorption is detected in the atmosphere of HD 209458 b, marking the first direct detection of an exoplanet atmosphere. #exoplanets #astronomy
2003 CE
First Exoplanet Imaged: 2M1207b
2M1207b is directly imaged orbiting a brown dwarf, providing the first direct image of an exoplanet. #exoplanets #astronomy
First Exoplanet Imaged: 2M1207b By Aldaron, a.k.a. Aldaron - Own work, incorporating public domain images for reference planets (see below), inspired by Thingg's size comparison, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=8902848
2005 CE
First Super-Earth: Gliese 876 d
Gliese 876 d is discovered, a super-Earth with a mass about 7.5 times Earth's, expanding the types of known exoplanets. #exoplanets #astronomy
First Super-Earth: Gliese 876 d By Trent Schindler, National Science Foundation - https://www.nsf.gov/news/news_summ.jsp?cntn_id=104243&org=NSF, Public domain, https://commons.wikimedia.org/w/index.php?curid=186432
Apr 24, 2007 CE
First Potentially Habitable Exoplanet: Gliese 581 c
Gliese 581 c is discovered in the habitable zone of its star, sparking interest in Earth-like exoplanets. #exoplanets #astrobiology
First Potentially Habitable Exoplanet: Gliese 581 c By Aldaron, a.k.a. Aldaron - Own work, incorporating public domain images for reference planets (see below), CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=11703403
Mar 7, 2009 CE
Kepler Space Telescope Launches
NASA's Kepler mission launches to discover Earth-sized exoplanets in the habitable zone using the transit method. #exoplanets #space
Kepler Space Telescope Launches By NASA - https://science.nasa.gov/toolkits/spacecraft-icons (image link), Public domain, https://commons.wikimedia.org/w/index.php?curid=76268556
Feb 2, 2011 CE
Kepler-11: Six Transiting Planets
Kepler-11 is announced with six transiting planets, demonstrating a compact multi-planet system. #exoplanets #astronomy
Kepler-11: Six Transiting Planets By NASA / Tim Pyle - New Planetary System image:[1], Public domain, https://commons.wikimedia.org/w/index.php?curid=12890676
Dec 5, 2011 CE
Kepler-22b: First Kepler Habitable Zone Planet
Kepler-22b is confirmed as the first Kepler planet in the habitable zone of a Sun-like star. #exoplanets #astrobiology
Kepler-22b: First Kepler Habitable Zone Planet By NASA/Ames/JPL-Caltech - http://kepler.nasa.gov/news/nasakeplernews/index.cfm?FuseAction=ShowNews&NewsID=165, Public domain, https://commons.wikimedia.org/w/index.php?curid=24187911
2012 CE
Alpha Centauri Bb Claimed
A planet is claimed around Alpha Centauri B, later retracted due to data analysis issues. #exoplanets #astronomy
Alpha Centauri Bb Claimed By ESO/L. Calçada/N. Risinger - ESO, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=23163877
2013 CE
Kepler-78b: Earth-sized Lava World
Kepler-78b is discovered, an Earth-sized planet with a very short orbit, later found to be a lava world. #exoplanets #astronomy
Kepler-78b: Earth-sized Lava World By Aldaron, a.k.a. Aldaron - Own work, incorporating public domain images for reference planets (see below), inspired by Thingg's size comparison, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=32381319
Feb 26, 2014 CE
Kepler-186f: First Earth-sized Planet in Habitable Zone
Kepler-186f is the first Earth-sized planet discovered in the habitable zone of another star. #exoplanets #astrobiology
Kepler-186f: First Earth-sized Planet in Habitable Zone By NASA Ames/SETI Institute/JPL-Caltech - [1], [2], Public domain, https://commons.wikimedia.org/w/index.php?curid=32229517
Jul 23, 2015 CE
Kepler-452b: Earth's Cousin
Kepler-452b is announced as a near-Earth-sized planet in the habitable zone of a Sun-like star, dubbed 'Earth's cousin.' #exoplanets #astrobiology
Kepler-452b: Earth's Cousin By NASA Ames/JPL-Caltech/T. Pyle - http://www.nasa.gov/image-feature/soaking-up-the-rays-of-a-sun-like-star-artistic-concept, Public domain, https://commons.wikimedia.org/w/index.php?curid=41807518
May 2, 2016 CE
TRAPPIST-1 System Announced
Three Earth-sized planets are discovered around the ultracool dwarf TRAPPIST-1; later expanded to seven. #exoplanets #astrobiology
TRAPPIST-1 System Announced By Processing and color compositing by Nrco0e; original images by Sloan Digital Sky Survey - Own work; processed from images acquired from the SDSS DR17 archive, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=191888700
Aug 24, 2016 CE
Proxima Centauri b Announced
An Earth-sized planet is discovered in the habitable zone of Proxima Centauri, the closest star to the Sun. #exoplanets #astrobiology
Proxima Centauri b Announced By ESO/M. Kornmesser - https://www.eso.org/public/images/ann16056a/, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=50869082
Feb 22, 2017 CE
TRAPPIST-1: Seven Earth-sized Planets
NASA announces the TRAPPIST-1 system hosts seven Earth-sized planets, three in the habitable zone. #exoplanets #astrobiology
Dec 14, 2017 CE
First Exoplanet from TESS: Pi Mensae c
TESS discovers its first exoplanet, Pi Mensae c, a super-Earth. #exoplanets #astronomy
First Exoplanet from TESS: Pi Mensae c By Mensa_constellation_map.png: Torsten Bronger derivative work: Kxx (talk) - Mensa_constellation_map.png, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=10850065
Apr 18, 2018 CE
TESS Launches
NASA's Transiting Exoplanet Survey Satellite (TESS) launches to survey bright stars for transiting exoplanets. #exoplanets #space
TESS Launches By Orbital ATK / NASA - https://svs.gsfc.nasa.gov/vis/a010000/a012700/a012782/TESS_alone_high_res.jpg https://svs.gsfc.nasa.gov/12782, Public domain, https://commons.wikimedia.org/w/index.php?curid=108981705
Sep 11, 2019 CE
Water Vapor Detected on K2-18b
Water vapor is detected in the atmosphere of K2-18b, a super-Earth in the habitable zone. #exoplanets #astrobiology
Water Vapor Detected on K2-18b By Illustration: NASA, ESA, CSA, Joseph Olmsted (STScI) Science: Nikku Madhusudhan (IoA) - https://webbtelescope.org/contents/media/images/2023/139/01H9R88HG8YXRMARWZ5B1YDT27, Public domain, https://commons.wikimedia.org/w/index.php?curid=137418814
Jan 6, 2020 CE
TOI-700 d: First Earth-sized Habitable Zone Planet by TESS
TESS discovers TOI-700 d, an Earth-sized planet in the habitable zone of its star. #exoplanets #astrobiology
TOI-700 d: First Earth-sized Habitable Zone Planet by TESS By NASA's Goddard Space Flight Center - https://www.jpl.nasa.gov/spaceimages/images/largesize/PIA23408_hires.jpg, Public domain, https://commons.wikimedia.org/w/index.php?curid=85681322
Dec 25, 2021 CE
James Webb Space Telescope Launches
JWST launches, designed to study exoplanet atmospheres and search for biosignatures. #exoplanets #astrobiology
James Webb Space Telescope Launches By NASA - https://www.jwst.nasa.gov/content/webbLaunch/whereIsWebb.html, Public domain, https://commons.wikimedia.org/w/index.php?curid=114125719
Jul 12, 2022 CE
JWST First Images Released
JWST releases its first scientific images, including spectra of exoplanet WASP-96b, revealing water vapor. #exoplanets #astronomy
Aug 25, 2022 CE
JWST Detects CO2 on WASP-39b
JWST detects carbon dioxide in the atmosphere of exoplanet WASP-39b, demonstrating its capability for atmospheric characterization. #exoplanets #astronomy
JWST Detects CO2 on WASP-39b By NASA, ESA, CSA, J. Olmsted (STScI) - Illustration (Artist’s Impression) of WASP-39 b and Its Star, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=125907007
Jan 11, 2023 CE
JWST Confirms Exoplanet LHS 475 b
JWST confirms its first exoplanet, LHS 475 b, an Earth-sized rocky planet. #exoplanets #astronomy
JWST Confirms Exoplanet LHS 475 b By NASA, ESA, CSA, Leah Hustak (STScI) - https://webbtelescope.org/contents/media/images/2023/102/01GNVXWS67QNTC7Z10FN2CJB1H, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=127670533
Sep 11, 2023 CE
JWST Detects Methane on Exoplanet
JWST detects methane in the atmosphere of exoplanet WASP-80b, providing insights into its chemistry. #exoplanets #astronomy
Mar 15, 2024 CE
JWST Finds Carbon Molecules on K2-18b
JWST detects carbon-bearing molecules including methane and CO2 on K2-18b, hinting at a possible water ocean. #exoplanets #astrobiology
May 10, 2024 CE
PLATO Mission Approved
ESA's PLATO mission is approved for launch in 2026 to find and characterize Earth-like exoplanets. #exoplanets #space )
PLATO Mission Approved By ESA/ATG Europe - https://www.esa.int/ESA_Multimedia/Images/2023/05/Plato_key_visual, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=175139220
Aug 1, 2024 CE
Over 5,500 Exoplanets Confirmed
The number of confirmed exoplanets surpasses 5,500, with thousands more candidates awaiting confirmation. #exoplanets #astronomy
Mar 20, 2025 CE
JWST Detects Potential Biosignature on Trappist-1e
JWST observes potential biosignature gases in the atmosphere of TRAPPIST-1e, a habitable zone planet. #exoplanets #astrobiology
JWST Detects Potential Biosignature on Trappist-1e By NASA/JPL-Caltech - Cropped from: PIA22093: TRAPPIST-1 Planet Lineup - Updated Feb. 2018, Public domain, https://commons.wikimedia.org/w/index.php?curid=76364487
Jun 15, 2026 CE
PLATO Mission Launches
ESA's PLATO mission launches to discover and characterize Earth-like exoplanets around Sun-like stars. #exoplanets #space )
Oct 1, 2027 CE
Ariel Mission Launches
ESA's Ariel mission launches to study exoplanet atmospheres on a large scale. #exoplanets #space )
May 1, 2028 CE
Nancy Grace Roman Space Telescope Launches
NASA's Roman Space Telescope launches, capable of direct imaging of exoplanets and microlensing surveys. #exoplanets #space
Nancy Grace Roman Space Telescope Launches By NASA - https://roman.gsfc.nasa.gov/gallery-spacecraftillustrations.html, Public domain, https://commons.wikimedia.org/w/index.php?curid=136706293
Dec 31, 2030 CE
Exoplanet Population Estimates Reach 100 Billion
Studies estimate that the Milky Way galaxy may host up to 100 billion exoplanets, with billions potentially habitable. #exoplanets #astrobiology
Exoplanet Population Estimates Reach 100 Billion By Jason Wang (Caltech)/Christian Marois (NRC Herzberg) - https://jasonwang.space/orbits.html, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=90872179
