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Ceres: Asteroid or Planet?
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Ceres: Asteroid or Planet? |
| Explanation |
Is Ceres [ http://en.wikipedia.org/wiki/Ceres_%28asteroid%29 ] an asteroid [ http://www.nineplanets.org/asteroids.html ] or a planet? Although a trivial designation to some, the recent suggestion by the Planet Definition Committee [ http://www.iau2006.org/mirror/www.iau.org/iau0601/iau0601_committee.html ] of the International Astronomical Union [ http://www.iau2006.org/mirror/www.iau.org/NEWS.55.0.html ] would have Ceres reclassified from asteroid to planet. A change in taxonomy might lead to more notoriety for the frequently overlooked world. Ceres [ http://www.pantheon.org/articles/c/ceres.html ], at about 1000 kilometers across, is the largest object in the main asteroid belt [ http://www.solstation.com/stars/asteroid.htm ] between Mars and Jupiter. Under the newly proposed criteria [ http://www.iau2006.org/mirror/www.iau.org/iau0601/iau0601_release.html ], Ceres would qualify as a planet because it is nearly spherical and sufficiently distant from other planets. Pictured above [ http://hubblesite.org/newscenter/newsdesk/archive/releases/2005/27/image/a ] is the best picture yet of Ceres, taken by the Hubble Space Telescope [ http://antwrp.gsfc.nasa.gov/apod/ap010806.html ] as part of a series of exposures ending in 2004 January. Currently, NASA's Dawn mission [ http://dawn.jpl.nasa.gov/ ] is scheduled to launch in 2007 June to explore Ceres and Vesta [ http://antwrp.gsfc.nasa.gov/apod/ap060820.html ], regardless of their future designations. |
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Jupiter, Vesta, and the Milk
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Jupiter, Vesta, and the Milky Way |
| Explanation |
In this gorgeous skyscape, gas giant Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap070329.html ] along with the stars and cosmic dust clouds of the Milky Way [ http://antwrp.gsfc.nasa.gov/apod/ap070330.html ] hang over the southern horizon in the early morning hours as seen from Stagecoach, Colorado, USA. Recorded on Thursday, Jupiter is the brightest object near picture center. Along with the stunning Milky Way, Jupiter is hard to miss, but a careful inspection of the view also reveals main belt [ http://www.solstation.com/stars/asteroid.htm ] asteroid Vesta [ http://antwrp.gsfc.nasa.gov/apod/ap060820.html ]. Of all the asteroids [ http://www.nineplanets.org/asteroids.html ] Vesta is the brightest and is now just bright enough to be visible to the naked eye from locations with very dark, clear skies. Vesta (as well as Jupiter) appears relatively bright now because it is near opposition, literally [ http://www.heavens-above.com/ gloss.asp?term=opposition ] opposite the Sun in planet Earth's sky and closest to Earth in its orbit. For Vesta [ http://dawn.jpl.nasa.gov/feature_stories/ Vesta_chart_descrip.asp ], this opposition offers the best viewing in many years. The year 2007 also coincides [ http://adsabs.harvard.edu/abs/1907Obs....30..103L ] with the 200th anniversary of the asteroid's discovery [ http://dawn.jpl.nasa.gov/DawnCommunity/ flashbacks/fb_06.asp ]. Starting late next month, NASA plans to launch the Dawn mission [ http://dawn.jpl.nasa.gov/index.asp ] intended to explore Vesta (and Ceres) and the main asteroid belt. |
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Small Worlds Ceres and Vesta
| Title |
Small Worlds Ceres and Vesta |
| Explanation |
Ceres [ http://www.planetary.org/explore/topics/asteroids_and_comets/ ceres.html ] and Vesta [ http://hubblesite.org/newscenter/archive/releases/ 1997/27 ] are, respectively, only around 950 kilometers and 530 kilometers in diameter - about the size of Texas and Arizona. But they are two of the largest of over 100,000 minor bodies [ http://nssdc.gsfc.nasa.gov/planetary/factsheet/ asteroidfact.html ] orbiting in the main asteroid belt [ http://www.solstation.com/stars/ asteroid.htm ] between Mars and Jupiter. These remarkably detailed Hubble Space Telescope images [ http://hubblesite.org/newscenter/archive/releases/ 2007/27/ ] show brightness and color variations across the surface of the two small worlds. The variations could represent large scale surface features or areas of different compositon. The Hubble image data will help astronomers plan for a visit by the asteroid-hopping Dawn spacecraft [ http://dawn.jpl.nasa.gov/index.asp ], scheduled for launch on July 7 and intended to orbit first Vesta [ http://antwrp.gsfc.nasa.gov/apod/ap070525.html ] and then Ceres [ http://antwrp.gsfc.nasa.gov/apod/ap060821.html ] after a four year interplanetary cruise. Though Shakespeare [ http://www.phrases.org.uk/meanings/305250.html ] might not have been impressed, nomenclature introduced by the International Astronomical Union in 2006 classifies nearly spherical Ceres as a dwarf planet [ http://en.wikipedia.org/wiki/Dwarf_planet ]. |
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