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The Stars
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.
See Also:
Keith's Moon Planting Page
Our Sun
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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Mirrors and Lenses
Many people believe that the main function of a telescope is just to make distant celestial objects appear bigger so that astronomers (even amateur astronomers) can see them better, but that really is a misconception. The fact is that telescopes work by gathering light. Magnifying distant objects is secondary. Telescopes gather light basically in two ways: through the use of lenses, and through the use of mirrors. The third way that telescopes gather light is by using a combination of lenses and mirrors.
A telescope that gathers light through the use of a lens is called a refractor telescope. The truth is that how much you spend on a refractor telescope is the determining factor of how well you will be able to see celestial objects. Inexpensive refractor telescopes (2.4 inch) have not-so-good optics and low light grasp. High-end refractor telescopes (3.5 inch) have almost perfect optics and much, much better light grasp.
Telescopes that gather light through the use of a mirror are called reflector telescopes. Refractors cost less per inch of aperture. They are less costly to manufacture because there is only one optical surface, and they lend themselves well to different designs and uses. Also, because the light doesn't have to pass through glass, the images are basically color free. Probably the best telescope for a novice astronomer is the Newtonian reflector. The cost factor is a plus for the refractor telescope, but the corresponding minus (there always is one) is that the primary mirror is ground to a concave shape, so the outside zone has a little longer focal length than the inner zone.
A catadioptic telescope is a compromise between a refractor and a reflector, because both lens and a mirror are used. Catadioptic telescopes are portable. They do not cost as much as a high-quality refractor telescope, but they cost a little more than a good-quality reflector telescope. Still, they are the best of both worlds.
Related Topics: NASA,
Telescope Jargon, Galaxies
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