18thand19thcentury Astronomy

In 1912, Henrietta Leavitt creates the Cepheid period-luminosity chart, which will later serve as the first cosmic yardstick, allowing astronomers to accurately measure the distance to far-away objects.

Discoveries: Leavitt discovers a correlation between Cepheids' period and luminosity
People: Henrietta Leavitt

In 1915, Einstein goes on to tackle greater questions of time, space, and gravity in his general theory of relativity.

In 1924, Edwin Hubble finds a Cepheid in the Andromeda Nebula, allowing him to measure the distance to the nebula. He finds it to be so far from earth that in fact Andromeda is a separate galaxy, and our Milky Way is only one small part of the universe.

In 1926, Erwin Schrödinger publishes his wave equations, providing mathematical explanations of Bohr's theories of quantum atomic structure. The following year, Werner Heisenberg states his uncertainty principle, which begins to explain the strange working of the subatomic world, a world that behaves unlike anything we can observe in our everyday life.

That same year, 1927, Georges LeMaitre develops a theory of the origins of the universe, which becomes knows as the "big bang."

In 1929, Edwin Hubble finds that very distant stars appear to be moving away from earth at a speed proportional to their distance hence finds proof that the universe is expanding.

# In 1931, Ernest Lawrence invents the cyclotron, which allows physicists to study the behavior of atomic particles accelerated at very high speeds. This inaugurates an age of "big science."

In 1965, Arno Penzias and Robert Wilson hear an annoying hiss in their satellite antenna, which they identify as cosmic microwave radiation left over from the big bang leading to its discovery.

In 1967, Jocelyn Bell finds a message from a distant star, the first identified pulsar in the universe

In 1976, Thomas Kibble suggests that the uneven distribution of matter in the universe can be explained by the existence of cosmic strings formed shortly after the big bang.

Today, physicists like Jim Gates continue to explore the mathematical workings of the subatomic world.
Nov. 3, 1957: The soviet Union lunches the first artificial satellite, Sputnik 1.

Oct. 4, 1957: Laika, a dog aboard Spunik 2, is the first animal in space.

Jan. 31, 1958: The United States Launches its first earth-orbiting satellite, Explorer 1

Sept. 4, 1959: A Soviet spacecraft, Luna 2, makes the first hard (crash) landing on the moon.

April 12, 1961: Cosmonuat Yuri Gagarin in Vostok 1 becomes the first person to orbit earth.

May 5, 1961: Alan Shepard in Mercury- Freedom 7 is the first American in Space.

Feb. 20, 1962: The First American to orbit the earth is Glenn aboard Mercury- Atlas 6

Sept. 29, 1962: Canada's first satellite, Alouette 1, is launched into orbit by NASA.

June 16, 1963 Velentina Tereshkova in Vostok 6 becomes the first woman in space.

March 18, 1965: The first walk in space is made by cosmonaut Alexei Leonov of Voskhod 2.

June 3, 1965: Edward White is the first American to walk in space.

Dec. 15, 1965: Gemini 6 and Gemini 7 carry out the first rendezvous of two spacecraft in orbit.

Feb. 3, 1966: Luna 9 makes the first soft (controlled) landing on the moon.

Aug. 10, 1966: NASA launches the first Lunar Orbiter to photograph potential lunar landing sites.

Jan. 27, 1967: Astronauts Virgil Grissom, Edward White, and Roger Chaffee die during a preflight test when a fire sweep through the Apollo 1 command module on the launch pad.

Dec. 21, 1968: NASA launches Apollo 8, the first manned spacecraft to orbit the moon.

July 20, 1969: Neil Armstrong and Edwin "Buzz" Aldrin land on the moon.

April 19, 1971: The first space station, Salyut 1, is launched

Dec. 14, 1972: Apollo 17 makes the last manned landing on the moon

May 14, 1973: Skylab space station is launched

July 17, 1975: Apollo 18 and Soyuz 19 docking orbit

Oct. 22, 1975: Venera 9 lander reaches Venus and transmits the first pictures from another planet's suface.

July 20, 1976: The unmanned spacecraft Viking 1 lands on mars

Sept. 5, 1977: Voyager 1 is launched to explore Jupiter, Saturn, Uranus, and Neptune.

Dec. 14, 1979: Europe enters the space age with the Araine 1 rocket, used to launch commercial satellites.

April 12, 1981: Columbia STS-1 is the first airplane-like craft to be launched into orbit.

Nov. 12-14, 1981: The Canadarm Remote Manipulator System is successfully operated for the first time on the second space shuttle flight.

June 13, 1983: The Pioneer 10 probe is the first man-made object to leave the solar system.

June 18, 1983: Salley Ride becomes the first American women in space.

Oct. 5, 1984: Marc Garneau is the first Canadian in space.

July 2, 1985: European Space Agency launches Giotto to study Comet Halley.

Jan. 28, 1986: Space Shuttle Challenger STS-51L explodes 73 seconds into the launch.

Feb. 20, 1986: Mir space station is launched.

Dec. 21, 1987: Vladimir Titov, Muso Manarov and Anatoly Levchenko arrive at the Mir space station and stay a year, a record for the longest stay in space.

April 25, 1990: The Hubble space telescope is released into orbit.

Jan. 22, 1992 Roberta Bondar becomes the first Canadian women in space.

Sept. 16, 1996: Shannon Lucid returns to Earth after 188 days aboard The Mir space station, an American and women's record for the longest stay in space.

July 4, 1997: A Pathfinder lands on Mars; 16,550 images are returned to Earth during the mission.

Oct. 29, 1998 Seventy-seven-year-old Gelnn returns to space aboard the shuttle discovery, becoming the oldest person in space.

Nov. 20, 1998: The first component of the International Space Station-- involving sixteen countries--is launched. The station will be completed in 2004.