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The Planet Saturn
The First Seven Astronauts
Everything starts somewhere, and the space program began in earnest with the selection of the first seven astronauts that would participate in manned space flight. The NASA selection committee was made up of Charles Donlan, a senior management engineer; Warren North, a test pilot engineer; Stanley White and William Argerson, flight surgeons; Allen Gamble and Robert Voas, psychologists; and George Ruff and Edwin Levy, psychiatrists.
When the selection committee began their task, they received 508 applications. This number was reduced to 110 candidates after records were reviewed. The 110 candidates were brought together at an undisclosed location. A battery of tests were given and interviews were conducted. It took a month but the number of possible candidates was reduced to 32.
The 32 candidates were then subjected to even more stressful physical, psychological, and mental examinations. They were given full-body x-rays, tested in pressure suits, endured a variety of cognitive tests and really intense interviews. Finally, 18 or the 32 were recommended to the Mercury program without any medical reservations.
The final choices were made by Robert Gilruth, who was the head of the Space Task Group, as well as Charles Donlan, Warren North, and Stanley White.
The first seven astronauts selected for the Mercury program (the first manned space flight program) were Scott Carpenter, L. Gordon Cooper Jr., John H. Glenn Jr., Virgil I. "Gus" Grissom, Walter M. Schirra Jr., Alan B. Shepard Jr., and Donald K. "Deke" Slayton. Their names will resound through history forever.
Six of the original seven flew in Project Mercury. Only "Deke" Slayton did not fly because of a heart condition that had not been discovered. Deke later flew as a crewmember of the Apollo-Soyuz Test Project.
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History of Astronomy
The Planet Uranus
William Herschel accidentally discovered the planet Uranus in 1781. Uranus had been seen many times before, but it had always been dismissed as a star.
Uranus is made up mostly of hydrogen and helium like Jupiter and Saturn, but it has higher concentrations of heavy elements. Our closest look at Uranus was given to us by Voyager 2 in 1986.
Uranus is one of the four "Giant Gas Planets" (the other three are Jupiter, Saturn, and Neptune). The rings around Uranus are made up of rock, rather than ice like those of Saturn. We do know that there are five large moons and at least 10 smaller moons. The rotational period of Uranus is a little over 17 hours, and its orbital period is 84 years.
Uranus appears to be a giant blue featureless ball. Voyager 2 got relatively close to Uranus and could not pick up any distinguishable features. It is believed that the upper atmosphere of Uranus has a high-level petrochemical haze that probably obscures features lower in the atmosphere. The blue color is caused by methane gas in the atmosphere. Methane gas absorbs red and orange light, which leaves more blue light.
Voyager 2 confirmed that Uranus has a magnetic field. The field is more than 50 times stronger than that of Earth and is tilted about 60 degrees.
The latest scientific data suggests that Uranus is surrounded by at least five rings. The brightest ring is called the Epsilon ring. Voyager 2 located two small shepherd moons for it, one just inside and one just outside. These two shepherd moons have been named Ophelia and Cordelia.
The most interesting moon that circles Uranus is Miranda. Miranda isn't very big, but it has some very interesting geological features. |
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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: Our Sun's Twin,
Telescope Accessories, Galileo Galilei
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