Date

Event

Sometime between 13 and 20 billion years ago

The Big Bang probably occurred.

~30,000 B.C.

Asian hunter-gatherers crossed over the frozen Bering Strait to become first humans in North America.

~3,000 B.C.

Stonehenge is built.

~2,000 B.C.

First solar-lunar calendars. Solar-lunar calendars used the sun and the moon to tell the time of day and the day of the week.

~280 B.C.

Aristrachus suggests the Earth revolves around the Sun. Before Aristrachus made this theory the sun and all the other planets were thought to revolve around the Earth. His theory was not accepted. He provides first estimation of the distance from the Earth to the Sun.

~240 B.C.

Eratosthenes measures the circumference of Earth. Using only basic geometry, his measurements were within 50 miles of the actual measurements!

~130 B.C.

Hipparchus develops the first accurate star map and star catalogue with over 850 of the brightest stars.

140 A.D.

Ptolemy suggests geocentric theory of the universe, that all the planets and even the Sun revolved around the Earth. His theory was believed for over 1,400 years, until Copernicus proved his theory wrong.

11th century A.D.

Vikings discover North America.

1492 A.D.

Columbus sails to the New World.

1543 A.D.

Copernicus publishes his heliocentric theory of the Universe, that all the planets and Earth revolve around the Sun.

1572 A.D.

Tycho Brahe, a famous Danish astronomer, used his naked eye to observe the night sky. He didn’t use a telescope because it wouldn’t be invented until 1608. Kepler would later use Brahe’s recorded observations in 1609 to describe the orbits of the planets around the Sun, which helped prove the geocentric theory was not correct.

1608 A.D.

Hans Lippershey, a Dutch spectacles maker, invents the telescope.

1609 A.D.

Galileo uses a telescope to discover 4 moons of Jupiter, the Moon's craters, and the Milky Way galaxy.

1609 A.D.

Kepler's Three Laws of Planetary Motion are announced. Kepler helped Copernicus’s planetary model become accepted.

1656 A.D.

Christian Huygens discovers Saturn's rings and Titan, the fourth moon of Saturn. He used a telescope he made himself.

1659 A.D.

Huygens notes markings on Mars.

1666 A.D.

Geovanni Cassini finds Martian polar ice caps.

1668 A.D.

The first reflecting telescope was built by Sir Isaac Newton.

1675 A.D.

Danish astronomer Ole Romer measures the speed of light.

1675 A.D.

Cassini discovers that Saturn's rings are split into two parts. Today the gap is called the "Cassini Division".

1687 A.D.

Newton publishes his theory of universal gravitation, the start of Modern Astronomy. He proved the way we are bound to Earth.

1705 A.D.

Halley correctly predicts the return of a comet (Halley's Comet) in 1758.

1758 A.D.

Johann Palitzsch observes Halley's Comet as predicted by Halley in 1705.

1776 A.D.

American Revolution begins.

1781 A.D.

Uranus discovered by Herschel

1781 A.D.

Messier discovers galaxies, nebula, and star clusters while looking for comets. He compiles a catalogue of these objects (Messier objects).

1801 A.D.

Piazzi discovers first asteroid, Ceres.

1846 A.D.

Johann Galle observes and discovers Neptune. His observations were based on mathematical calculations by French astronomer Joseph Leverrier and English astronomer John Couch Adams.

1861 A.D.

American Civil War begins.

1877 A.D.

Asaph Hall discovers Phobos and Deimos, the moons of Mars.

1877 A.D.

Shiaparelli observes the canals on Mars.

1878 A.D.

The Great Red Spot on Jupiter becomes prominent.

1905 A.D.

Mount Wilson Observatory was established for study of the Sun.

1905 A.D.

Albert Einstein introduces special Theory of Relativity.

1908 A.D.

Hertzsprung describes giant and dwarf stars.

1914 A.D.

World War I begins.

1916 A.D.

Albert Einstein introduces his general Theory of Relativity.

1923 A.D.

Edwin Hubble shows that galaxies exist outside the Milky Way galaxy.

1926 A.D.

Robert Goddard uses first liquid fuel rocket.

1927 A.D.

Oort shows the center of the Milky Way galaxy is in the constellation Sagittarius.

1930 A.D.

Clyde Tombaugh discovers Pluto.

1931 A.D.

Karl Jansky discovers cosmic radio waves.

1937 A.D.

First radio telescope built by Grote Reber.

1939 A.D.

World War II begins.

1945 A.D.

United States drops atomic bomb on Japan.

1957 A.D.

Sputnik, first object to orbit the Earth, launched by the Russians.

1958 A.D.

Explorer 1, the first U.S. satellite to orbit the Earth, is launched.

1961 A.D.

Soviet Yuri Gargarin becomes the first man in space.

1962 A.D.

John Glenn becomes first American to orbit Earth.

1963 A.D.

Soviet Valentina Tereshkova becomes the first woman in space, orbiting Earth 45 times.

1966 A.D.

First successful landings on the Moon by Luna 9 (U.S.S.R) and Surveyor I (U.S.A.)

1968 A.D.

Apollo astronauts are the first astronauts to orbit the Moon and see its far side.

1969 A.D.

Neil Armstrong and Buzz Aldrin walk on the Moon as part of Apollo 11 mission.

1970 A.D.

The Russian Venera 7 becomes first to land successfully on the surface of Venus.

1972 A.D.

The U.S. launches Pioneer 10, the first satellite to go to Jupiter.

1974 A.D.

The U.S. Mariner 10 probe sends the first image of Mercury.

1976 A.D.

The U.S. Viking probes land on Mars.

1977 A.D.

Discovery of Uranus' rings

1978 A.D.

Discovery of Charon, the moon of Pluto, by James Christy and Robert Harrington

1980 A.D.

U.S. Voyager 1 sends back first images of Saturn and its rings to Earth.

1983 A.D.

Sally Ride becomes the first American woman in space.

1986 A.D.

U.S. Voyager 2 closes in on Uranus.

1986 A.D.

Space Shuttle Challenger disaster.

1990 A.D.

Hubble Space Telescope put into orbit from space shuttle Discovery.

1992 A.D.

Pope John Paul II announces that the Catholic Church erred in condemning Galileo's work that proved the work of Copernicus was valid, that the planets circle the Sun and not the Earth.

1994 A.D.

Comet Shoemaker Levy crashes into Jupiter.

1995 A.D.

Galileo space probe reaches Jupiter.

1997 A.D.

Mars Pathfinder lands on the Red Planet.

1997 A.D.

Cassini begins its journey to Saturn.

1998 A.D.

The Lunar Prospector reaches the Moon.

1998 A.D.

Construction begins on the International Space Station.

1998 A.D.

Galileo discovers origin of Jupiter's Rings.

1998 A.D.

John Glenn returns to space after 36 years. He becomes the oldest man in space.

1999 A.D.

Chandra X-ray Observatory is put into orbit. Col. Eileen Collins becomes first woman shuttle commander.

1999 A.D.

NASA loses the Mars Climate Orbiter and the Mars Polar Lander.

2000 A.D.

Space Shuttle Endeavor makes a detailed, global map of Earth

2000 A.D.

The NEAR spacecraft reaches asteroid Eros.

2000 A.D.

New evidence found for water on Mars.

2001 A.D.

The Mir space station crashed in the Pacific Ocean.