Assignment 4. The Changing Pluto

The Changing Pluto

Pluto
Pluto, used to be considered as the ninth planet of the solar system, is a now the largest dwarf planet in the Kuiper Belt, which is a shadowy zone consisting of trillions of comets beyond the orbit of by Neptune [1]. It was first discovered by the American astronomer Clyde Tombaugh in 1930 as a planet and later reclassified as a dwarf planet by the International Astronomical Union in 2006. 
Before the Clyde Tombaugh, the American astronomer Percival Lowell first realized the existence of Pluto through the observation of the orbit of Neptune and Uranus, which is different than predicted unless there is another planet’s gravity tugging the two planets from the beyond. However, even though he spent his remaining 11 years in calculating the position and searching for the "trans-Neptunian" planet [2], he died in 1916 without finishing his research.  Later on, with the fund provided by Lowell's broth - Harvard University President A. Lawrence Lowell - the research started again and a new telescope was built in 1929.

Clyde Tombaugh
Clyde Tombaugh, peers into an instrument
Credit: Lowell Observatory
Clyde Tombaugh joined the research of planet X after he entered the Lowell Observatory in 1929. He was born in 1906 in Kansas and worked as a farm boy when he was young. He was obsessed with the astronomy and unimpressed with the store-bought telescope. So he made his own telescope when he was just 20. When he was 22, he made a telescope by putting together a 23cm reflector out of the crankshaft of a 1910 Buick and parts from a cream seperator[3]. By this telescope, he had the opportunity to make detailed observations of  Jupiter and Mars. He sent the result to the Lowell Observatory to get some feedback from the professional astronomers. What surprised him was that the observatory offered him a position. After his discovery of the Pluto, Tombaugh attended the University of Kansas. After graduating from the M.A. in astronomy in 1939, he returned to the Lowell Observatory and worked there until 1946. Then he went to teach at New Mexico State University and retired in 1973[4].
Discovery of Pluto
When Tombaugh joined the team, the observatory was equipment with a new camera that could take photographs of the sky. And with the help of a device, called blink compactor, which makes the far away, like stars and galaxies, fixed in the photographs, and shows the movement of the closer planets, Tombaugh noticed the movement of the Planet Pluto
The photographs of the discovery of the Pluto
Credit: Lowell Observatory
.The name Pluto was named after the Greek god of the underworld, suggested by Eleven-year old Venetia Burney from England.


 Facts of Pluto & Plutino
Pluto's radius is 1151 kilometers, which is about 1/6 of the width of Earth, which is smaller than Earth's Moon. The average distance from Pluto to the Sun is 39 Astronomical units and it takes 5.5 hours for the sunlight to reach there. It takes 248 years for Pluto to orbit one circle around the Sun and 153 hours for self-rotation (one day on Pluto). Pluto is mainly formed by the ice and rock,  just like others in the Kuiper Belt [5].
Plutoids and their Moons
However, in 2005, Astronomers have found the Eris in the Kuiper Belt, which is about the same size
as Pluto and even heavier than Pluto[7]. This led to the International Astronomical Union decision in reclassified the Pluto as a dwarf planet. Later on, they also decided that the object similar to Pluto should be called Plutoids. Plutoid is neither a Terrestrial planet which is small, rocky objects that close to the Sun, nor a Jovian planet, which is a large ball of liquid gas and ice that far from the Sun. It is just an icy body that orbits around the Sun.
Some of the Plutinos

Another kind of object is called Plutino, which is similar icy bodies as the Plutoid but has unique orbiting circumstances. The Plutinos sit in the 3:2 mean-motion resonance with Neptune, which means for every two orbits a plutino makes, Neptune orbits three times.
Approximately one-fourth of the known trans-Neptunian objects are Plutinos[8]. The reason why there are so many Plutinos might because they are formed by the comets and ice ejected by the Uranus and Neptune.










Reference
[1] [5]https://solarsystem.nasa.gov/planets/dwarf-planets/pluto/in-depth/
[2]https://lowell.edu/in-depth/pluto/the-discovery-of-pluto/
[3]https://www.space.com/19824-clyde-tombaugh.html
[4]https://www.britannica.com/biography/Clyde-Tombaugh
[6]https://cseligman.com/text/planets/plutoid.htm
[7]https://en.wikipedia.org/wiki/Eris_(dwarf_planet)
[8]http://www2.ess.ucla.edu/~jewitt/kb/plutino.html

Image from:
https://www.space.com/19824-clyde-tombaugh.html
https://cseligman.com/text/planets/plutoid.htm
https://en.wikipedia.org/wiki/Plutino

评论

  1. Vince2018年3月19日 06:37

    Good work, but you missed some questions posed in the assignment.

    - Was Pluto's a true theoretical prediction based on celestial mechanics, like that of Neptune?
    - How was the knowledge of the properties of Pluto changing in the decades after discovery, and what is the current verdict on the nature of the body, as well as the original search methods.

    There's also no summary...

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