In the early 1900’s, after the discovery of Neptune, scientists began making calculations for something else that appeared to be affecting the movements of the two outer planets.
In 1930, Clyde Tombaugh discovered the long-hypothesized planet now called Pluto; after continuing the research of Percival Lowell, who originally suspected the planet’s existence but unfortunately died exhausted from his research in 1916.
Pluto is too faint to be seen from smaller telescopes and no details of the planet’s surface have ever
been seen until today.
After traveling over THREE BILLION MILES, for nearly a decade through our solar system, at more than 30,000 miles an hour New Horizons has finally approached the dwarf planet.
“The exploration of Pluto and its moons by New Horizons represents the capstone event to 50 years of planetary exploration by NASA and the United States,” said NASA Administrator Charles Bolden.
The size of Pluto has puzzled astronomers since its discovery. It was originally thought to have a diameter greater than the size of the Earth, but later estimates proposed that the planet was actually smaller than Mars. This theory has several problematic implications, as a planet that small would not have had such an influence on Neptune and Uranus in the way that Lowell initially discovered.
Mission scientists have found Pluto to be 1,473 miles (2,370 kilometers) in diameter, somewhat larger than many prior estimates.
New Horizons is the latest in a long line of scientific accomplishments at NASA, including multiple rovers exploring the surface of Mars, the Cassini spacecraft that has revolutionized our understanding of Saturn and the Hubble Space Telescope, which recently celebrated its 25th anniversary.
Follow @NASANewHorizons on Twitter to keep up with the latest data from the spacecraft.