| Revision as of 21:26, 13 October 2002 view sourceBryan Derksen (talk | contribs)Extended confirmed users95,333 editsmNo edit summary← Previous edit | Revision as of 21:33, 13 October 2002 view source Bryan Derksen (talk | contribs)Extended confirmed users95,333 edits some minor rearrangement to better merge the "Pluto debate" sectionNext edit → | ||
| Line 68: | Line 68: | ||
| Pluto has one natural ], ]. Little is known about Pluto because of its great distance from Earth and because no exploratory spacecraft have visited Pluto yet. | Pluto has one natural ], ]. Little is known about Pluto because of its great distance from Earth and because no exploratory spacecraft have visited Pluto yet. | ||
| ⚫ | Some researchers have suggested that Pluto and its moon Charon were moons of Neptune that were knocked out of Neptune's orbit. It is now thought that not only was Pluto never Neptune's moon, but that ] was originally an independant body much like Pluto which was captured by Neptune. | ||
| === The Pluto debate === | === The Pluto debate === | ||
| The planet Pluto was originally discovered in ]. At that point in time it was the farthest object known in the solar system and was discovered as much by luck as anything else. |
The planet Pluto was originally discovered in ]. At that point in time it was the farthest object known in the solar system and was discovered as much by luck as anything else. When Pluto was found it didn't have the mass to explain the problems in Neptune's orbit, but it was nevertheless identified as the solar system's ninth planet. | ||
| When Pluto was found, however, it didn't have the mass to explain the problems in Neptune's orbit. Nonetheless, it became identified as the solar system's ninth planet. | |||
| ⚫ | Some researchers have suggested that Pluto and |
||
| Since that time, telescopes and imaging systems have improved considerably. Pluto's moon ] has been discovered and this enabled us to figure out Pluto's mass, showing it to be smaller than even ]. It was also found that Pluto is made largely of ice. | Since that time, telescopes and imaging systems have improved considerably. Pluto's moon ] has been discovered and this enabled us to figure out Pluto's mass, showing it to be smaller than even ]. It was also found that Pluto is made largely of ice. | ||
| Line 83: | Line 81: | ||
| This planetary sciences debate landed in newspaper headlines, editorials, and on the internet in early 1999. Thoughts that Pluto might be "demoted" as a planet left certain sectors of the public angry. Such news outlets as the <i>BBC News Online</i>, the <i>Boston Globe</i> and <i>USA Today</i> all printed stories noting that the ] was considering dropping Pluto's planetary status. "Save Pluto" websites sprang up, and school children sent letters to astronomers and the IAU. | This planetary sciences debate landed in newspaper headlines, editorials, and on the internet in early 1999. Thoughts that Pluto might be "demoted" as a planet left certain sectors of the public angry. Such news outlets as the <i>BBC News Online</i>, the <i>Boston Globe</i> and <i>USA Today</i> all printed stories noting that the ] was considering dropping Pluto's planetary status. "Save Pluto" websites sprang up, and school children sent letters to astronomers and the IAU. | ||
| On February 3, 1999 Brian Marsden of the Minor Planets Center inadvertently fueled the debate when he issued an editorial in the Minor Planets Electronic Circular 1999-C03 noting that the 10, |
On February 3, 1999 Brian Marsden of the Minor Planets Center inadvertently fueled the debate when he issued an editorial in the Minor Planets Electronic Circular 1999-C03 noting that the 10,000th minor planet was about to be numbered and this called for a large celebration (the IAU celebrates every thousandths numbered minor planet in some way). He suggested that Pluto be honored with the number 10,000, giving it "dual citizenship" of sorts as both a major and a minor planet. | ||
| Between the media reports and the Minor Planets Electronic Circular, IAU General Secretary Joannes Anderson issued a press release that same day stating there were <i>no</i> plans to change Pluto's planetary status. | Between the media reports and the Minor Planets Electronic Circular, IAU General Secretary Joannes Anderson issued a press release that same day stating there were <i>no</i> plans to change Pluto's planetary status. | ||
Revision as of 21:33, 13 October 2002
| Discovery | |||||||
|---|---|---|---|---|---|---|---|
| Discoverd by | C. Tombaugh | ||||||
| Discoverd in | 1930 | ||||||
| Orbital characteristics | |||||||
| Mean radius | 5.91352×10 km | ||||||
| Eccentricity | 0.2482 | ||||||
| Revolution period | 248y 197d 5.5h | ||||||
| Inclination | 17.148° | ||||||
| Number of satellites | 1 | ||||||
| Physical characteristics | |||||||
| Equatorial diameter | 2320 km | ||||||
| Surface area | 17 million km | ||||||
| Mass | 1.290×10 kg | ||||||
| Mean density | 2.05 g/cm | ||||||
| Surface gravity | 0.4 m/s | ||||||
| Rotation period | 6d 9h 17.6m | ||||||
| Axial tilt | 122.52° | ||||||
| Albedo | 0.30 | ||||||
| Surface temp. |
|
||||||
| Atmospheric characteristics | |||||||
| Atmospheric pressure | 0 - 0.01 kPa | ||||||
| Nitrogen | 90% | ||||||
| Methane | 10% | ||||||
This photo of Pluto, taken with the Hubble Space Telescope, is currently our best view of this distant object.
Pluto is the ninth and smallest planet of our solar system. It was discovered by the astronomer Clyde Tombaugh at the Lowell Observatory in Arizona in 1930. Tombaugh was searching for a "Planet X" to explain the orbit of Neptune; further analysis, with seven decades more data about Neptune's position, has resolved the perceived anomaly without need for an additional gravitational pull on Neptune. Its highly eccentric orbit makes Pluto the eighth-most distant planet from the Sun for part of each orbit; this most recently occurred from February 7, 1979 through February 11, 1999. Pluto orbits in a 3/2 resonance with Neptune. Because of its small size and eccentric orbit, there has been some debate over whether it truly should be classified as a planet. There is mounting evidence that Pluto may in fact be a member of the Kuiper Belt, only one of a large number of distant icy bodies. A subclass of such objects have been dubbed plutinos, after Pluto.
Pluto has an atmosphere when it is close to perihelion; the atmosphere freezes out as Pluto moves further from the Sun.
Pluto has one natural satellite, Charon. Little is known about Pluto because of its great distance from Earth and because no exploratory spacecraft have visited Pluto yet.
Some researchers have suggested that Pluto and its moon Charon were moons of Neptune that were knocked out of Neptune's orbit. It is now thought that not only was Pluto never Neptune's moon, but that Triton was originally an independant body much like Pluto which was captured by Neptune.
The Pluto debate
The planet Pluto was originally discovered in 1930. At that point in time it was the farthest object known in the solar system and was discovered as much by luck as anything else. When Pluto was found it didn't have the mass to explain the problems in Neptune's orbit, but it was nevertheless identified as the solar system's ninth planet.
Since that time, telescopes and imaging systems have improved considerably. Pluto's moon Charon has been discovered and this enabled us to figure out Pluto's mass, showing it to be smaller than even Mercury. It was also found that Pluto is made largely of ice.
In September of 1992 scientists began discovering hundreds of other, smaller, icy bodies in the area of the solar system beyond the orbit of Neptune. These objects are now deemed members of the Edgeworth-Kuiper Belt. The continued discovery of these objects began a debate that goes on to this day: is Pluto a planet or simply the largest (known) example of an Edgeworth-Kuiper Belt object?
This planetary sciences debate landed in newspaper headlines, editorials, and on the internet in early 1999. Thoughts that Pluto might be "demoted" as a planet left certain sectors of the public angry. Such news outlets as the BBC News Online, the Boston Globe and USA Today all printed stories noting that the International Astronomical Union was considering dropping Pluto's planetary status. "Save Pluto" websites sprang up, and school children sent letters to astronomers and the IAU.
On February 3, 1999 Brian Marsden of the Minor Planets Center inadvertently fueled the debate when he issued an editorial in the Minor Planets Electronic Circular 1999-C03 noting that the 10,000th minor planet was about to be numbered and this called for a large celebration (the IAU celebrates every thousandths numbered minor planet in some way). He suggested that Pluto be honored with the number 10,000, giving it "dual citizenship" of sorts as both a major and a minor planet.
Between the media reports and the Minor Planets Electronic Circular, IAU General Secretary Joannes Anderson issued a press release that same day stating there were no plans to change Pluto's planetary status.
The debate continues, and recent discoveries have made the position of Pluto as a major planet perhaps even harder to sustain. On October 7, 2002 Mike Brown and Chad Trajillo announced at a meeting of the American Astronomical Society their discovery of "Quaoar." This new object in the Edgeworth-Kuiper Belt is 13000km in diameter making it a bit more than half the size of Pluto. Quaoar is the largest object discovered in the solar system since Pluto itself in 1930. Some astronomers think it is only a matter of time before a Edgeworth-Kuiper Belt object larger than Pluto is discovered.
Exploration of Pluto
NASA has approved a mission to Pluto, to be conducted by The Southwest Research Institute. (Referred to as "Pluto Express")
The planet is named both for the Roman god Pluto, and for the astronomer Percival Lowell, who predicted that a planet would be found beyond Neptune.
Solar system:
Sun - Mercury - Venus - Earth - Mars - Asteroids - Jupiter - Saturn - Uranus - Neptune - Pluto - Comets