Philosophy
2006: Pluto, once the ninth planet from the sun, is downgraded to a mere “dwarf planet.” Our solar system loses a favorite kid brother and now has, officially, only eight planets.
Pluto was discovered by American astronomer Clyde Tombaugh on Feb. 18, 1930. Comparing photographs taken of the same section of sky over several nights in January, Tombaugh identified a moving object against a background of stationary stars.
Based on the predictions of two colleagues at the Lowell Observatory, he’d been searching for a planet outside the orbit of Neptune at the time. The photographs convinced him he had found it.
Tombaugh announced his discovery on March 13. The planet was officially named Pluto, after the Roman god of the underworld, on May 1, 1930.
But astronomers had trouble accepting Pluto as a full-fledged planet almost since its discovery. Size was always an issue — it’s smaller than Earth’s moon — and its orbit around the sun doesn’t conform to the path followed by the eight “classical” planets. Astronomers also began discovering similarly sized bodies in the vicinity of Pluto, diluting its cachet even more.
Finally, in 2006, the International Astronomical Union officially downgraded Pluto’s status to “dwarf planet.”
The IAU decided on this definition of a planet:
Because Pluto crosses the orbital path of Neptune, it has not cleared the neighborhood of its orbit, throwing it (and similarly Ceres, Eris, Haumea and Makemake) into the category of dwarf planet.
The International Astronomical Union decided on this definition of a dwarf planet:
(It is important to keep the moons out of the definition because there are seven moons in our solar system bigger than Pluto: Io, Europa, Ganymede, Callisto, Titan, Triton and Earth’s own moon.)
So, Pluto is now merely a dwarf planet in the Kuiper belt — like it or not.
- Sayonara Planet Pluto
Tova Hagler, 10, left, reads through the names of the planets with her brother, Yaakov, 5, as they walk through the Scales of the Universe exhibit at the Rose Center for Earth and Space at the American Museum of Natural History in New York. Pluto was...
- Pluto Fizzled At Iau's Rio Meeting
The IAU's Rio meeting never discussed the sensitive issue of Pluto's status. "Pluto still not a planet after astronomy meeting" by Dan Vergano August 13th, 2009 USA Today An international astronomy meeting ended Thursday in Rio de Janeiro,...
- Prairie State Government Declares Pluto A Planet
This will make some people happy. "Illinois restores Pluto's planetary status" 13 March is Pluto Day, senate declares by Lester Haines March 6th, 2009 The Register The State of Illinois has decided it's unhappy with Pluto's 2006 expulsion...
- "pluto A Planet" Poll
Should Pluto be considered a planet? Yes....9 [90%] No....1 [10%] Just a guess, but I would bet that those voted "Yes" are lay persons and not bona fide astronomers. Such controversy. Simply put...if the astronomers wish to redefine the characteristics...
- Pluto="plutoid"
Pluto Does this satisfy everyone now? ""Plutoids": the new name for Pluto-like dwarf planets" by Jon Cartwright June 12th, 2008 physicsworld.com Pluto sub-classification The International Astronomical Union (IAU) has decided that Pluto — and other...
Philosophy
Yesterday [2006] Pluto was declared a non-planet
"Aug. 24, 2006: Pluto Deplanetized"
by
Tony Long and Doug Cornelius
August 24th, 2010
Wired
by
Tony Long and Doug Cornelius
August 24th, 2010
Wired
2006: Pluto, once the ninth planet from the sun, is downgraded to a mere “dwarf planet.” Our solar system loses a favorite kid brother and now has, officially, only eight planets.
Pluto was discovered by American astronomer Clyde Tombaugh on Feb. 18, 1930. Comparing photographs taken of the same section of sky over several nights in January, Tombaugh identified a moving object against a background of stationary stars.
Based on the predictions of two colleagues at the Lowell Observatory, he’d been searching for a planet outside the orbit of Neptune at the time. The photographs convinced him he had found it.
Tombaugh announced his discovery on March 13. The planet was officially named Pluto, after the Roman god of the underworld, on May 1, 1930.
But astronomers had trouble accepting Pluto as a full-fledged planet almost since its discovery. Size was always an issue — it’s smaller than Earth’s moon — and its orbit around the sun doesn’t conform to the path followed by the eight “classical” planets. Astronomers also began discovering similarly sized bodies in the vicinity of Pluto, diluting its cachet even more.
Finally, in 2006, the International Astronomical Union officially downgraded Pluto’s status to “dwarf planet.”
The IAU decided on this definition of a planet:
A celestial body that (a) is in orbit around the sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit.
Because Pluto crosses the orbital path of Neptune, it has not cleared the neighborhood of its orbit, throwing it (and similarly Ceres, Eris, Haumea and Makemake) into the category of dwarf planet.
The International Astronomical Union decided on this definition of a dwarf planet:
A celestial body that (a) is in orbit around the sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, (c) has not cleared the neighborhood around its orbit, and (d) is not a satellite.
(It is important to keep the moons out of the definition because there are seven moons in our solar system bigger than Pluto: Io, Europa, Ganymede, Callisto, Titan, Triton and Earth’s own moon.)
So, Pluto is now merely a dwarf planet in the Kuiper belt — like it or not.
- Sayonara Planet Pluto
Tova Hagler, 10, left, reads through the names of the planets with her brother, Yaakov, 5, as they walk through the Scales of the Universe exhibit at the Rose Center for Earth and Space at the American Museum of Natural History in New York. Pluto was...
- Pluto Fizzled At Iau's Rio Meeting
The IAU's Rio meeting never discussed the sensitive issue of Pluto's status. "Pluto still not a planet after astronomy meeting" by Dan Vergano August 13th, 2009 USA Today An international astronomy meeting ended Thursday in Rio de Janeiro,...
- Prairie State Government Declares Pluto A Planet
This will make some people happy. "Illinois restores Pluto's planetary status" 13 March is Pluto Day, senate declares by Lester Haines March 6th, 2009 The Register The State of Illinois has decided it's unhappy with Pluto's 2006 expulsion...
- "pluto A Planet" Poll
Should Pluto be considered a planet? Yes....9 [90%] No....1 [10%] Just a guess, but I would bet that those voted "Yes" are lay persons and not bona fide astronomers. Such controversy. Simply put...if the astronomers wish to redefine the characteristics...
- Pluto="plutoid"
Pluto Does this satisfy everyone now? ""Plutoids": the new name for Pluto-like dwarf planets" by Jon Cartwright June 12th, 2008 physicsworld.com Pluto sub-classification The International Astronomical Union (IAU) has decided that Pluto — and other...