The crew aboard the International Space Station celebrated Thanksgiving.
Scientists observed the biggest explosion in the universe, 390 million light-years away.
Elon Musk announced that he was building a spaceship called Starship that would travel to Mars and return to Earth.
Amateur astronomer Gennady Borisov discovered a strange comet in another star system.
An asteroid, dubbed 'City Killer,' came closer to Earth than the moon and was almost undetected.
The first photo of a black hole that was taken in 2017 was announced to the public.
The discovery of an Earth-like planet 3.2 times bigger than our world was announced.
A Neptune-sized exomoon became the first one discovered outside the Solar System.
Twelve new moons were discovered in Jupiter's orbit, bringing the planet's total number of moons to 79.
Astronomers witnessed the first neutron star collision.
An orbital-class rocket was successfully reused for the first time.
Astronomers announced the discovery of an Earth-like planet named Proxima b.
Researchers announced that gravitational waves had been discovered.
The latter of two total lunar eclipses was seen from the Americas.
NASA announced they had found 'Earth's bigger, older cousin.'
The Rosetta Philae became the first-ever probe to land on a moving comet.
Asteroid 2014 RC passed safely by Earth at a distance of 24,800 miles away.
The International Astronomical Union named Pluto's fourth and fifth moons Kerberos and Styx.
Two Earth-like planets in one solar system were discovered.
Europe's Planck spacecraft found evidence that our universe is 13.8 billion years old.
SpaceX's Dragon became the first commercial spacecraft to dock at the International Space Station.
The European Space Agency successfully launched the Vega launch rocket for the first time.
Asteroid 2005 YU55 came dangerously close to hitting the Earth.
A blue moon and a lunar eclipse occurred on the same day.
Two satellites collide in space.
Instruments used to observe Venus found two-thirds of the planet's southern hemisphere brightened after aerosols were triggered on an 'astronomical' scale.
Two newly discovered moons orbiting Pluto were named Nix and Hydra.
After seven months of travel, the Mars Reconnaissance Orbiter arrived safely to Mars.
The European Space Agency launched the Venus Express, the first European spacecraft to reach Venus.
The European Huygens space probe lands on Saturn's moon Titan.
The solar system's largest known dwarf planet is discovered.
Radiation from an explosion on the magnetar SGR 1806-20 reached Earth.
Cassini orbiter released the Huygens probe, which successfully landed on Saturn's moon Titan.
At just 0.010AU from Earth, 4179 Toutatis became the closest asteroid to Earth in the last century.
The Cassini–Huygens spacecraft became the first to enter Saturn's orbit.
Mars made its closest approach to Earth in nearly 60,000 years.
The Cosmic Call 2 mission occurred at the Eupatoria Planetary Radar in western Crimea.
The last signal from the Pioneer 10 space probe was received.
Osiris became the first discovered exoplanet with an atmosphere.
Space welcomed its first tourist from Earth.
The first crew arrived at the International Space Station onboard a Soyuz spacecraft.
A conjunction of Sun, Mercury, Venus, Mars, Jupiter, Saturn, and the Moon occurred.
The last total solar eclipse of the 20th century occurred and was visible from Europe and Asia.
Two new moons orbiting Uranus were announced in Nature magazine.
Jupiter's moon was found to have a liquid ocean under a thick crust of ice.
American Psychologist Timothy Leary and Star Trek creator Gene Roddenberry were launched into orbit after being cremated.
The super-bright comet 'Hale-Bopp' reached its closest point to Earth at a distance of 1.215 AU, making it visible to the naked eye.
The Hubble Space Telescope captured the first images of the surface of Pluto.
People in South Asia witnessed a total eclipse that lasted 2 minutes and 9 seconds.
Two new moons of Saturn were found in photos from the Hubble Space Telescope by Astronomers Amanda S. Bosh and Andrew S. Rivkin.
