sourced from: http://interviewly.com/i/nasas-new-horizons-oct-2014-reddit
Pluto was once recognized as one of nine major planets orbiting the sun but is now only considered as a dwarf planet. In modern day astronomy, Pluto is seen as one of the largest members of the Kuiper Belt [1]. The Kuiper belt is a disc shaped ring and its a region of icy objects located billions of kilometers away from the sun [2].
Pluto was once classified as the ninth planet in our solar system therefore being extremely far away from our earth. Due to the enormous distance, there's is little information about the planets size or surface condition. According to the article in www.space.com, Pluto is estimated to have a diameter equivalent to less than one fifth of the Earth. It guesses that Pluto's surface probably contains ices of various composition such as methane and nitrogen at the surface, a mantle of water ice under the surface, and a rocky core at the center. NASA's hubble space telescope has been able to provide observations and evidence of the different compositions of gas.
This Hubble Space telescope from NASA has shown that Pluto has a very eccentric orbits therefore creating huge variance in distance from the sun as well as penetrating the planet Neptune's orbit. As Pluto orbits closer to the sun, the ice on the surface of the planets temporarily melts and forms a thin atmosphere around the planet containing mostly nitrogen and methane. Due to Pluto's extremely low gravity causes the temporary atmosphere to extend higher than earths atmosphere. While Pluto has its atmosphere, it can apparently experience strong winds. Once Pluto orbits further away from the sun, it's atmosphere beings to freeze and eventually disappears. Pluto apparently has one of the most cold surfaces in the entire solar systems with approximately 375 degrees Fahrenheit below zero. Astronomers also discovered that Pluto had a very large moon and they have a very short distance between each other in terms of other planets and their moons.[1]
Discovery of Pluto
Sourced by: http://sciencefiction.com/2014/10/12/pluto-may-just-fact-planet/
Pluto was discovered less than 100 years ago, which is very recent in terms our known existence. An astronomer at the Lowell Observatory in Flagstaff, Arizona by the name, Clyde W. Tombaugh, discovered the planet on February 18, 1930. Originally, it was an American Astronomer by the name Percival Lowell who proposed that there was another planetary body somewhere in the range of Neptune and Uranus because he had observed something affecting the orbits of the two planets have been the gravitational pull of something large. Lowell referred to the large body as "Planet X" in 1905 and unfortunately died in 1916, sadly never being able to discover the planet.[3]
More than a decade later the Lowell Observatory decided to continue on with research of "Planet X" done by Percival Lowell, the founder of the observatory. Clyde W. Tombaugh was hired to discover the existence of this unfounded planet using a 13-inch telescope that the Observatory had built just for the purpose of it's discovery. Tombaugh had to contribute an immense number hours and hard work before discovering the planet Pluto. On February 18, 1930 Tombaugh was able to examine the photographic plates that were outputted by the telescope. The Lowell Observatory was not ready to announce the discovery until more research took place and on March 13,1930, which would have been Percival Lowell;s 75th birthday, they confirmed the discovery.[3]
The "Planet X" eventually needed a name and was chosen by an 11 year old girl, Venetia Burney. The name "Pluto" often refers to the roman god of the underworld which fit due to the similar surface conditions of the planet. The name also hon ours Percival Lowell because the first two letters in "Pluto" and his initials. [3]
Sourced From :http://www.icollector.com/Clyde-W-Tombaugh_i11385124
Clyde W Tombaugh also discovered many galaxies and clusters of stars with this improved telescope. He also made various observations of the surfaces on Mars, Venus, Saturn, Jupiter, and the moon. After the discovery of Pluto, Tombaugh attended the University of Kansas and going on to receive his M.A. in astronomy. After graduation he returned back to the observatory to continue his astronomical work and he cataloged over 30,000 objects in the universe. He also went on to teaching at a few colleges and university. Even when he decided to retire he still continued to observe the sky and advise the university. [4]
As mentioned before the telescope used in the discovery of Pluto at the Lowell Observatory was very advanced and it was equipped with photography. This camera within the telescope was used to take two pictures of the sky on various days. They also used a device known as a blink comparator which switch views between pictures rapidly. In these pictures, the stars and galaxies were stationary but orbiting objects could be identified due to the motion across the sky. Apparently, Clyde W. Tombaugh close to 7000 hours analyzing each pair of photos which contained 150000 to 1 million stars in a single photo. After precise measurements and study, Tombaugh was able to identify the movement of one particular object[5].
The discovery of Pluto was not a true theoretical predication based on celestial mechanics. The Titus Bode law explained the approximate distance from planet to planet going away from the sun. Using Newtonian physics and the Titus Bode law, the planets and their distances from each other made sense. Astronomers noticed that there was a supposed "missing planet" between mars and Jupiter that should be in place rather than a gap. Guiseppe Piazzi in 1801 discovered Ceres, a large asteroid/ minor planet, and many other minor planets forming and asteroid belt. Mathematical astronomers used the Titus bode law to explain the gap between mars and Jupiter. The law also pointed out that there should another planet after Jupiter and due to this theory astronomers later found Uranus.[6]
Le Verrier, another famous astronomers noticed that the orbit of Uranus didn't match its theorized paths as well as Neptune which was found due to this reason very reason. At the time Le verrier used Titus Bode Law to predict the paths of Neptune and Uranus and published his predictions. However with modern day science we figure out that Uranus, Neptune, and Pluto do not follow the Titus Bode law, therefore proving that Le Verrier and other astronomer's findings completely luck. Even the discovery of Pluto was due to luck.[7]
Changes to Plutos Discovery
Originally, Pluto was thought to be a similar size as the earth and therefore there was no question about it being a ninth planet. It was considered as the ninth planet in our solar system for 70 years. In 1978 astronomers discovered Pluto's largest moon, Charon. With this discovery they were able to approximate Pluto size at around 2400 km, which would make it the smallest planet in our solar system but the largest object past the orbit of Neptune. With advances in technology and observatories, astronomers were able to find many other celestial objects similar to Pluto and its moon in the Kuiper belt. There are approximately 70000 icy object with the same composition as Pluto within this Kuiper belt that extends out from the orbit of Neptune to 55 AU.
Astronomers had to decide on what exactly was the definition of a planet. There are three criteria that a celestial object has to meet to be considered a planet:
1. It needs to be in orbit around the sun
2. It has to have a strong enough gravitational pull to form itself into a sphere
3. It needs to have a clear dominant gravitational orbit
Unfortunately, Pluto did not meet the third criteria because it is in orbit along with tens of thousands of other objects in the kuiper belt. Astronomers decided that any celestial objects that also dont meet the third requirement is considered a dwarf planet. [9]
Plutinos
"Pluto and Eris were the first worlds to be classified as Plutoids, a special class of dwarf planets that orbit our sun in the icy region beyond the orbit of Neptune"[10]. Terrestrial planets are small rock and metallic objects orbiting close to the sun and Jovian planets are large objects with low density mainly made up of liquid composition, gases, and ices. Pluto is definitely not Terrestrial and is similar to a Jovian planet but because of its size cannot be classified as Jovian either. Due to this problem, astronomers have decided to create a new classification known as "Plutoids" to classify other objects like Pluto. Plutinos is a sub category of Plutoids but they are distinguished by the distinct way they orbit the sun. Pluto orbits in a perfect whole number ratio of 3 to 2 for the length of its orbital period compared to that of Neptune. Plutinos all share a similar ratio in orbital period either 3 to 2 or 4 to 3 or 2 to 1 but in any case it's a ratio of whole number.[10]
Sources (footnotes)
1. http://www.space.com/43-pluto-the-ninth-planet-that-was-a-dwarf.html
2. http://solarsystem.nasa.gov/planets/profile.cfm?Object=KBOs
3. http://history1900s.about.com/od/1930s/qt/Pluto.htm
4. http://www.britannica.com/EBchecked/topic/598927/Clyde-W-Tombaugh
5. http://ircamera.as.arizona.edu/NatSci102/NatSci102/lectures/pluto.htm
6. http://www.space.com/19824-clyde-tombaugh.html
7. http://www.fromquarkstoquasars.com/that-pluto-controversy/
8. http://www.splung.com/content/sid/7/page/solarsystem
9. http://www.universetoday.com/13573/why-pluto-is-no-longer-a-planet/
10. https://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=6823
need more info on plutinos
ReplyDeletegood work