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Our Sun's Twin
Telescope Jargon
There is a language of astronomy. You need to know what the terms mean before you buy a telescope to ensure that you buy the telescope that is best suited for your needs. Some of the terms you will hear are:
1. Magnification and aperture: On the box that a telescope comes in, these two terms are represented by numbers like 6 x 30 or 8 x
50.
a. The first number represents the magnification. The number 6 means that distant objects appear to be 6 times their size when viewed through the telescope. Magnification is not as important, however, as aperture.
b. Aperture is represented by the second number and tells you the surface area of the lens or mirror of the telescope. The primary function of a telescope is to gather light. Aperture is more important than magnification in viewing celestial objects.
2. Focal length: Focal length is the distance that light travels from the telescope's lens or mirror to the focal point inside the telescope. The size of the image at the focal point will be larger the longer the focal point is.
3. Focal ratio: The term "focal ratio" is the ratio between the aperture and the focal length.
4. Refractor telescope: The refractor telescope gathers light through the use of a lens. Refraction is one of three ways in which telescopes gather light.
5. Reflector telescope: A reflector telescope gathers light through the use of a mirror.
6. Catadioptic telescope: A catadioptic telescope gathers light through the use of both lenses and mirrors.
7. Equatorial mount: An equatorial mount is a telescope mount with one axis that is parallel to the earth's axis, and points to the celestial North Pole.
8. Altazimuth Mount: An altazimuth mount is a telescope mount with two axes. It allows for movement in two directions, horizontally and vertically.
See Also:
Astrology - Wikipedia, the free encyclopedia
Galileo Galilei
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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Astronomy For Kids - KidsAstronomy.com
Keith's Moon Planting Page
Pluto demoted - no longer a Planet!
The Future of Travel: Aquatic to Cosmic Destinations
Asteroids, Comets and Meteors
NASA
In 1958, the Congress of the United States enacted, and the President Dwight D. Eisenhower signed, the National Aeronautics and Space Administration Act (NASA). The act begins with a very simple statement; "An Act to provide for research into the problems of flight within and outside the Earth's atmosphere, and for other purposes."
The Cold War between the United States and (what was) the Soviet Union was in full swing. With the passing and signing of the act that established NASA, what has come to be known as the "space race" was kicked off. The Soviet Union had launched Sputnik 1 and had an apparent head start in the race to space.
The United States caught up quickly. In January 1958, Explorer 1 (America's first earth satellite) was launched.
Then NASA launched human space flight initiatives with Mercury's single astronaut program (flights during 1961-1963) to determine if a human could survive in space.
The Project Gemini (flights during 1965-1966) with two astronauts to was used to practice space operations, like rendezvousing and docking spacecraft and extravehicular activity (EVA or space walks).
This was followed with Project Apollo (flights during 1968-1972) to explore the Moon. Since then NASA has conducted robotic missions to the Moon (Ranger, Surveyor, and Lunar Orbiter); Venus (Pioneer Venus), Mars (Mariner 4, Viking 1 and 2), and the outer planets (Pioneer 10 and 11, Voyager 1 and 2).
NASA has had its problems over the years. The space shuttle Challenger blew up on January 28, 1986, killing seven astronauts. The space program was grounded for two years. Another tragedy happened on February 1, 2003, when the space shuttle Columbia disintegrated on re-entry. All seven people on board were killed instantly.
Space travel is not without its dangers, but space in the next great frontier for mankind to conquer. You can be sure that the space program and NASA will continue into the foreseeable future.
Related Topics: About Telescopes,
Galileo Galilei, Carl Sagan
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