Amazing Astronomy

                                                                             D. L. Rabinowitz


                                                             Eris was first spotted in 2003 during a Palomar Observatory survey of the outer solar system by Mike Brown, a professor of planetary astronomy at the California Institute of Technology; Chad Trujillo of the Gemini Observatory; and David Rabinowitz of Yale University. The discovery was confirmed in January 2005, and was submitted as a possible 10th planet of our solar system since it was the first object in the Kuiper Belt found to be bigger than Pluto.Eris is named for the ancient Greek goddess of discord and strife. The name fits since Eris remains at the center of a scientific debate about the definition of a planet.Eris' moon, Dysnomia, is named after Eris' daughter who is the demon goddess of lawlessness.





                                                            It takes icy Eris 557 Earth years to complete a single orbit around our sun. The plane of Eris' orbit is well out of the plane of the solar system's planets and extends far beyond the Kuiper Belt, a zone of icy debris beyond the orbit of Neptune.The dwarf planet is often so far from the sun that its atmosphere collapses and freezes on the surface in an icy glaze. The coating gleams brightly, reflecting as much sunlight as freshly fallen snow. Scientist's believe surface temperatures to vary from about -359 degrees Fahrenheit (-217 degrees Celsius) to -405 degrees Fahrenheit (-243 degrees Celsius). The thin atmosphere will thaw in hundreds of years as Eris gets closer to the sun, revealing a rocky surface scientists believe is similar to Pluto.





                                                          Though the dwarf planet Eris on the edge of the solar system is much denser than Pluto, the two frigid worlds are nearly exactly the same size, a new study finds.Astronomers accurately measured Eris' diameter for the first time using observations made late last year, when they caught the dwarf planet as it passed in front of a dim star. The observations, made using several telescopes in Chile, revealed that Eris and Pluto are pretty much identical in size, making them "almost perfect" twins, researchers said.The researchers also conclude that Eris is a spherical body. And, by studying the motion of Eris' moon Dysnomia, they peg the dwarf planet to be about 27 percent heavier than Pluto, which means it's considerably denser than Pluto as well.