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  4. 13
  5. Harvard College Observatory

Events on March 13 in history

Harvard College Observatory
1930Mar, 13

The news of the discovery of Pluto is telegraphed to the Harvard College Observatory.

The Harvard College Observatory (HCO) is an institution managing a complex of buildings and multiple instruments used for astronomical research by the Harvard University Department of Astronomy. It is located in Cambridge, Massachusetts, United States, and was founded in 1839. With the Smithsonian Astrophysical Observatory, it forms part of the HarvardSmithsonian Center for Astrophysics.

HCO houses a collection of approximately 500,000 astronomical plates taken between the mid-1880s and 1989 (with a gap from 19531968). This 100-year coverage is a unique resource for studying temporal variations in the universe. The Digital Access to a Sky Century @ Harvard project is digitally scanning and archiving these photographic plates.

Harvard College ObservatoryHarvard College Observatory
Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of bodies beyond the orbit of Neptune. It was the first object to be discovered in the Kuiper belt, and remains the largest known body in that area.

After Pluto was discovered in 1930, it was declared to be the ninth planet from the Sun. Beginning in the 1990s, its status as a planet was questioned following the discovery of several objects of similar size in the Kuiper belt and the scattered disc, including the dwarf planet Eris. This led the International Astronomical Union (IAU) in 2006 to formally define the term planet—excluding Pluto and reclassifying it as a dwarf planet.

Pluto is the ninth-largest and tenth-most-massive known object directly orbiting the Sun. It is the largest known trans-Neptunian object by volume but is less massive than Eris. Like other Kuiper belt objects, Pluto is primarily made of ice and rock and is relatively small—one-sixth the mass of the Moon and one-third its volume. It has a moderately eccentric and inclined orbit during which it ranges from 30 to 49 astronomical units or AU (4.4–7.4 billion km) from the Sun. This means that Pluto periodically comes closer to the Sun than Neptune, but a stable orbital resonance with Neptune prevents them from colliding. Light from the Sun takes 5.5 hours to reach Pluto at its average distance (39.5 AU).

Pluto has five known moons: Charon (the largest, with a diameter just over half that of Pluto), Styx, Nix, Kerberos, and Hydra. Pluto and Charon are sometimes considered a binary system because the barycenter of their orbits does not lie within either body.

The New Horizons spacecraft performed a flyby of Pluto on July 14, 2015, becoming the first and, to date, only spacecraft to do so. During its brief flyby, New Horizons made detailed measurements and observations of Pluto and its moons. In September 2016, astronomers announced that the reddish-brown cap of the north pole of Charon is composed of tholins, organic macromolecules that may be ingredients for the emergence of life, and produced from methane, nitrogen and other gases released from the atmosphere of Pluto and transferred 19,000 km (12,000 mi) to the orbiting moon.

References

  • Pluto
  • Harvard College Observatory

Choose Another Date

Events on 1930

  • 12Mar

    Salt March

    Mahatma Gandhi begins the Salt March, a 200-mile march to the sea to protest the British monopoly on salt in India
  • 6Apr

    Salt Satyagraha

    Gandhi raises a lump of mud and salt and declares, "With this, I am shaking the foundations of the British Empire," beginning the Salt Satyagraha.
  • 7Jul

    Hoover Dam

    Industrialist Henry J. Kaiser begins construction of Boulder Dam (now known as Hoover Dam).
  • 6Sep

    Hipólito Yrigoyen

    Democratically elected Argentine president Hipólito Yrigoyen is deposed in a military coup.
  • 24Oct

    Getúlio Vargas

    A bloodless coup d'état in Brazil ousts Washington Luís Pereira de Sousa, the last President of the First Republic. Getúlio Vargas is then installed as "provisional president".

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