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Our Sun's Twin
The Demotion of Pluto
The year was 1930. An astronomer, Clyde Tombaugh, was just 24 years old. He was studying the night sky at Lowell Observatory in Arizona when he discovered what would come to be known as Pluto…the ninth planet in our solar system. On January 23, 1930, Clyde saw a dim speck moving among the stars. It was quickly hailed as not only the ninth planet in our solar system, but the first planet discovered by an American. Americans were so proud!
There were a lot of names suggested for the new planet that Tombaugh had discovered. It was his prerogative to choose the name. Suggestions flowed in from all over the world. "Pluto" was suggested by then-11-year-old Venetia Burney from Oxford, England. She wanted to name the planet after Mickey Mouse's dog (Mickey's dog Pluto debuted that same year). Tombough liked the name and chose it. Venetia still lives in England and is quoted as having said, "It has now been satisfactorily proven that the dog was named after the planet, rather than the other way round."
Problem is, Pluto is no longer a planet. It didn't change, disintegrate, or disappear from the night sky. Rather, it fell victim to what some describe as "politics."
Pluto is no longer considered a planet thanks to votes cast by only 424 astronomers (5% of the membership) on the very last day of the meeting of the International Astronomical Union (IAU) in Prague in 2006.
Mike Brown, an astronomer from CalTech (and another American), recently discovered another Pluto-sized object that will not be called a planet either, under the new guidelines.
Many of those who are in a position to know say that the decision will not stand and that textbooks should not be rewritten just yet. The vote has been taken, but the debate isn't over.
See Also:
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Our Sun
The Planet Neptune
Adams and Leverrier predicted the existence of the planet Neptune back in 1845. Neptune is very difficult to observe from the earth because of (1) the distance, and (2) the earth's atmosphere. The closest and best look that we have had at Neptune was provided by the Voyager 2 flyby in 1989.
Neptune is the most distant planet from the sun. It was once believed that Pluto was a planet Pluto beyond Neptune, but astronomers have declared that Pluto is not a planet but one of many dwarf planets in our solar system.
Neptune has a diameter that is about four times larger than earths. Computer models suggest that Neptune has a rocky core that comprises about 15 earth masses at the center, but there is no confirmation of this theory. Neptune has a rotation period of about 16 hours. Neptune has an internal heat source, and it produces about 2.7 times more heat than it absorbs.
Strong winds, bright, high-altitude clouds, and two large dark spots attributed to long-lived giant storm systems were reveled by the 1989 Voyager flyby. Wind speeds are as high as 739 miles per hour. The larger of the two dark spots that Voyager reveals is called the "Great Dark Spot."
Neptune's rings were first detected from Earth in 1983, but no real study could be conducted at that time. It wasn't until the data supplied by the Voyager 2 flyby was available that any determination about the rings could be disseminated. There are two bright rings and two fainter rings. The rings rotate in the same direction as Neptune, and they are all close to the equator.
Triton and Nereid are the two large moons of Neptune and are visible from Earth. Voyager 2 discovered six more moons, and one of them is actually larger than Nereid; but it is difficult to see because it orbits so close to Neptune. |
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The Planet Saturn
Our Sun's Twin
Jorge Melendez of the Australian National University, and Ivan Ramirez of the University of Texas at Austin, are both astronomers from Peru. Using the Harlan J. Smith Telescope at McDonald Observatory located atop Mount Locke and Mount Fowlkes in the Davis Mountains of West Texas, they discovered the best candidate as a twin to our sun that has been found to date in November 2007. The findings by Melendez and Ramirez suggest that our sun's chemical composition is not unique, as some previously thought.
The star found by the Peruvian astronomers is in the constellation Draco, which is over 200 light years away from our solar system. HIP 56948, the star in question is more like our sun than any yet seen. The star may be a billion years older than the sun.
There have been three other possible twins to our sun located, but there is a major difference in the amount of lithium they contained. These stars -- 18 Scorpius, HD 98618, and HIP 100963 -- have all been contenders, but they all contain several times more lithium than our sun. This difference has led astronomers to believe that our sun was possibly unique because of its low amount of lithium. Now, it seems, maybe our sun is not so unique after all.
The search for solar twins to our sun is important because astronomers use our sun as a baseline for a variety of astronomical studies, and studying our own sun is very difficult because it is too close and too bright.
The discovery of HIP 56948 by Melendez and Ramirez lays to rest the belief that our sun is somehow completely unique and that the uniqueness is what allowed life to spring up and thrive and raises the possibility (no, probability) that life exists in other places in the universe. Maybe we aren't alone.
Related Topics: History of Astronomy,
Nicolaus Copernicus, Mirrors and Lenses
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