Sputnik 1 launch
4 October 1957 · date only
Sputnik 1 became the first artificial satellite to orbit Earth. Its radio signals made the beginning of the space age something people could listen to from the ground.
Explore these milestonesBeginnings that still echo.
A satellite’s first signal. A spacecraft’s touchdown. An image that changes what we can see. Follow twelve scientific beginnings beyond the familiar annual anniversary.
All original dates fall within 1900–2100. The broader homepage catalog also includes earlier figures with separate calendar-only calculations; this detail-page collection stays within the validated astronomical range. Dates without a documented time are clearly marked.
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First human spaceflight
12 April 1961 · date only
Yuri Gagarin’s Vostok 1 flight made him the first human to travel into space and orbit Earth. The flight opened the era of human space exploration.
Explore these milestonesApollo 11 Moon landing
20 July 1969 · documented UTC minute
The lunar module Eagle landed in the Sea of Tranquility, bringing humans to the surface of another world for the first time. The landing is distinct from the first moonwalk, which began on 21 July in UTC.
Explore these milestonesVoyager 2 launch
20 August 1977 · date only
Voyager 2 began a journey that would take it past all four giant planets. It remains the only spacecraft to have visited Uranus and Neptune, making its launch a starting point for an extraordinary planetary tour.
Explore these milestonesVoyager 1 launch
5 September 1977 · date only
Voyager 1 set out to study the outer planets and continued toward interstellar space. Its launch links the close-up exploration of Jupiter and Saturn with a much longer investigation of the Sun’s surroundings.
Explore these milestonesHubble Space Telescope launch
24 April 1990 · date only
Space shuttle Discovery carried Hubble into orbit. Observing above most of Earth’s atmosphere gave astronomers a new view of distant galaxies, stellar nurseries and the changing universe.
Explore these milestonesFirst International Space Station module
20 November 1998 · date only
The launch of Zarya placed the first International Space Station module in orbit. It began the physical assembly of a laboratory built through international cooperation.
Explore these milestonesHiggs boson discovery announcement
4 July 2012 · date only
The ATLAS and CMS collaborations at CERN announced a new particle consistent with the Higgs boson. The date marks a public scientific announcement, rather than a single instant when the particle was first produced.
Explore these milestonesPhilae comet landing
12 November 2014 · date only
Rosetta’s Philae lander reached comet 67P/Churyumov–Gerasimenko. The first soft landing on a comet gave researchers a new way to investigate material preserved from the early Solar System.
Explore these milestonesFirst black hole image released
10 April 2019 · date only
The Event Horizon Telescope collaboration released the first image of a black hole’s shadow, in galaxy M87. Telescopes around the world worked together as a planet-sized observing instrument.
Explore these milestonesPerseverance Mars landing
18 February 2021 · date only
Perseverance landed in Jezero crater to investigate ancient environments and collect samples. Its arrival began a new phase in the search for evidence of past habitability on Mars.
Explore these milestonesJames Webb Space Telescope launch
25 December 2021 · date only
An Ariane 5 rocket launched Webb on its journey toward the Sun–Earth L2 region. Its infrared observations study early galaxies, forming stars and the atmospheres of distant planets.
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