July 20, 1969: The US wins the race
for the Moon when Neil Armstrong and
Buzz Aldrin step off Apollo 11 onto the
lunar surface.
1971: Russia launched its first space
station, Salyut 1, into orbit.
1983: The first infrared telescope
was launched.
In 1990, the first space-based optical
telescope, the Hubble Space Telescope,
was launched and has to date provided
the most detailed images of the
Universe.
November 2, 2000, the first set of
long-term resident astronauts arrive at
the International Space Station:
Commander William M. (Bill) Shepherd
of NASA and cosmonauts Sergei Krikalev
and Yuri Gidzenko of Roscosmos.
2006: The International
Astronomical Union (IAU) adopted a
new definition of “planet" . A new
distinct class of objects called dwarf
planets was also defined. Pluto was
reclassified as a dwarf planet.
On July 14, 2015, with the successful
encounter of Pluto by NASA's New
Horizons spacecraft, the United States
becomes the first nation to explore all
of the “nine” major planets. The debate
surrounding Pluto’s “planethood” is
reignited.