1584 — Giordano Bruno proposes that stars are distant suns with their own planets and possibly other inhabited worlds.
1609 — Galileo makes the first telescopic observations of Mars.
1655 — Christiaan Huygens discovers Titan.
1676 — Ole Rømer measures the speed of light.
1781 — William Herschel discovers Uranus.
1877 — Giovanni Schiaparelli maps “canali” on Mars.
1895 — Percival Lowell promotes the idea of Martian canals.
1917 — Heavy elements detected in the spectrum of Van Maanen 2, later interpreted as planetary debris.
1938 — Rupert Wildt identifies methane and ammonia in Jupiter’s atmosphere.
1950 — Enrico Fermi poses the Fermi Paradox.
1957 — Sputnik launches.
1959 — Cocconi & Morrison publish the first modern SETI (Search for Extraterrestrial Intelligence)proposal.
1960 — Frank Drake conducts Project Ozma.
1961 — Drake formulates the Drake Equation.
1963 — Pulsars discovered.
1965 — Mariner 4 returns the first close‑up images of Mars.
1967 — Jocelyn Bell Burnell discovers the first pulsar.
1971 — Mariner 9 maps Mars globally.
1972 — Pioneer 10 becomes the first spacecraft to leave the inner Solar System.
1976 — Viking 1 & 2 land on Mars and perform the first life‑detection experiments.
1977 — Voyager 1 detects complex organic chemistry in Titan’s atmosphere.
1977 — The “Wow! Signal” detected during a SETI search.
1980 — Voyager reveals Titan’s thick atmosphere and Europa’s fractured icy surface.
1983 — IRAS (Infrared Astronomical Satellite) conducts the first all‑sky infrared survey, detecting debris disks around stars.
1984 — First circumstellar disk imaged around Beta Pictoris.
1988 — Planetary companion to Gamma Cephei suggested.
1992 — First confirmed exoplanets discovered around pulsar PSR B1257+12.
1994 — Third planet (Draugr) found in the PSR B1257+12 system.
1995 — First exoplanet around a Sun‑like star confirmed: 51 Pegasi b.
1996 — ALH84001 Martian meteorite announced as possible fossil evidence of life (later disputed).
1997 — Galileo spacecraft finds strong evidence of a subsurface ocean on Europa.
1999 — First transiting exoplanet observed: HD 209458 b.
2001 — First exoplanet atmosphere detected (sodium in HD 209458 b).
2003 — First microlensing exoplanet discovered.
2003 — NASA launches the Spitzer Space Telescope.
2003 — ESA launches Herschel, the largest infrared telescope ever flown.
2004 — Mars rovers Spirit and Opportunity find strong evidence of ancient water.
2004 — Cassini–Huygens detects lakes and seas on Titan.
2004 — First super‑Earth discovered (55 Cancri e).
2005 — First direct image of an exoplanet (2M1207 b).
2005 — Spitzer makes the first direct detection of infrared light from an exoplanet (HD 209458 b, TrES‑1).
2005 — Cassini discovers geysers on Enceladus.
2006 — CoRoT spacecraft launches.
2007 — Spitzer produces the first temperature map of an exoplanet (HD 189733 b).
2007 — First multi‑planet system directly imaged (HR 8799).
2008 — Phoenix lander confirms water ice on Mars.
2008 — Methane detected in Mars’ atmosphere.
2009 — Kepler Space Telescope launches.
2009 — WISE (Wide‑field Infrared Survey Explorer) launches, discovering brown dwarfs and debris disks.
2010 — Gliese 581 g announced (existence debated).
2010 — Kepler discovers its first rocky planet, Kepler‑10b.
2011 — Kepler identifies Kepler‑22b, first confirmed habitable‑zone planet around a Sun‑like star.
2012 — Alpha Centauri Bb announced (later disputed).
2012 — Curiosity rover confirms ancient Mars once had habitable lakes.
2013 — Kepler data suggests billions of Earth‑size habitable‑zone planets exist.
2014 — Kepler‑186f confirmed.
2014 — Curiosity confirms ancient Mars had conditions favorable for microbial life.
2014 — Spitzer helps refine the orbits and properties of the TRAPPIST‑1 planets.
2015 — TRAPPIST telescope discovers three Earth‑size planets around TRAPPIST‑1.
2015 — Kepler‑452b announced.
2016 — TRAPPIST‑1 expanded to seven Earth‑size planets.
2016 — Proxima Centauri b confirmed.
2017 — NASA refines TRAPPIST‑1 system details.
2017 — Cassini mission ends after confirming Enceladus’ ocean contains organics.
2018 — TESS launches.
2018 — Kepler mission ends.
2019 — Water vapor detected in the atmosphere of K2‑18 b.
2019 — ESA’s CHEOPS satellite launches.
2020 — TESS confirms TOI‑700 d.
2020 — Confirmed exoplanets surpass 4,000.
2020 — Phosphine controversially detected in Venus’ atmosphere.
2020 — Spitzer mission ends after 16 years.
2021 — James Webb Space Telescope launches.
2021 — Confirmed exoplanets surpass 4,500.
2022 — JWST detects CO₂ in WASP‑39 b.
2022 — JWST begins characterizing TRAPPIST‑1 planets.
2023 — JWST detects preliminary, debated dimethyl sulfide (DMS) on K2‑18 b.
2023 — Adaptive optics advances improve direct imaging.
2024 — JWST provides detailed atmospheric data on TRAPPIST‑1 planets.
2024 — Habitability models refined to include stellar flares and atmospheric escape.
2025 — Confirmed exoplanets reach 6,000.
2025 — Perseverance rover reports a potential biosignature in Martian samples.
2025 — NASA identifies a possible protocell formation pathway on Titan.
2026 — ESA’s PLATO mission planned to launch.
2026 — NASA’s Roman Space Telescope planned to launch.
2027 — NASA’s Dragonfly mission scheduled to launch to Titan.
2029 — ESA’s Ariel mission planned to launch.
2030 — Europa Clipper arrives at Jupiter.
2031 — ESA’s JUICE mission arrives at Jupiter.
2030s — ELT, GMT, and TMT begin directly imaging Earth‑like planets.
2035+ — NASA’s Habitable Worlds Observatory aims to directly image Earth‑like planets.
2035+ — Starshade concepts may enable imaging of Earth‑like planets.
2035+ — Interferometric arrays proposed to map continents and oceans on nearby exoplanets.
2035+ — Next‑generation SETI arrays planned for ultra‑sensitive technosignature searches.