tag:blogger.com,1999:blog-4956467315767826165.post4123308366633097932..comments2022-02-18T20:42:22.965-08:00Comments on Discoveries & Inventions Around The World: Discovery of a New Planet Leaves The Solar System With Only 8 PlanetsAringsburghttp://www.blogger.com/profile/06294967059097346197noreply@blogger.comBlogger1125tag:blogger.com,1999:blog-4956467315767826165.post-75273354698738679132009-03-03T21:06:00.000-08:002009-03-03T21:06:00.000-08:00The answer to the number of planets in our solar s...The answer to the number of planets in our solar system is not eight--it is still in question, with many currently counting 13. Only four percent of the IAU voted on the demotion of Pluto, and most were not planetary scientists. Their decision was immediately rejected by hundreds of professional astronomers led by Dr. Alan Stern, Principal Investigator of NASA's New Horizons mission to Pluto. Stern and like minded scientists rejected the criterion that an object has to "clear its orbit" to be a planet. They prefer a broader planet definition that includes any non-self-luminous spheroidal body orbiting a star. That gives us 13 planets: Mercury, Venus, Earth, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, Pluto, Haumea, Makemake, and Eris. Interestingly, Eris' co-discoverer, Dr. David Rabinowitz, signed the petition rejecting the IAU planet definition and the demotion of Pluto.<BR/><BR/>The IAU definition makes no sense in that it states dwarf planets are not planets. That is like saying a grizzly bear is not a bear. It is also contrary to the use of the word "dwarf" in astronomy, where dwarf stars are still stars, and dwarf galaxies are still galaxies. Also, the IAU definition classifies objects solely by where they are while ignoring what they are. If Earth were in Pluto's orbit, according to the IAU definition, it would not be a planet either.<BR/><BR/>Visit my Pluto blog at http://laurele.livejournal.com for more on worldwide efforts to overturn the controversial demotion. This debate is far from over.Laurel Kornfeldhttps://www.blogger.com/profile/02387883186244337619noreply@blogger.com