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Ham the Chimp
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:
Telescopes.com: Shop Telescopes and Telescope Eyepieces
Astronomy Funny Bone
The Stars
Our sun is a star. It is one of the billions of stars in the Milky Way Galaxy. On a clear night, when you look up at the sky, you can see thousands of stars with your naked eye. If you have a pair of binoculars or a telescope, you can see more stars than you could ever hope to count.
Each star is unique, but they all share things in common as well. Stars are born from interstellar gas clouds, nuclear fusion causes them to shine and stars die. Sometimes the death of a star is a very dramatic event.
Cold interstellar clouds or nebula, like the Orion Nebula and the Eagle Nebula, are the incubators and nurseries from which stars are born. An extremely simplified description is that gravitational collapse happens and forms a rotating gas globule. The resulting globule spins faster and faster. The central core becomes a star while the other material becomes planets or asteroids.
The life of a star begins and ends with a battle between two forces: gravity and pressure. It takes energy for a star to live, and this energy comes almost entirely from nuclear fusion of lighter elements into heavier elements. This is the energy through which a star can shine for millions or billions of years.
Stars fuse hydrogen to helium for most of their lifetime. This is referred to as the "main sequence" of a star's life. Our sun, Vega, Sirius, and Spica are all stars that are in their main sequence. Once the hydrogen in the core of a star has been used up, the star becomes a red giant like Betelguese, Arcturus, Aldebaran and Antares.
A star's life is limited because the hydrogen at the core is not self-replenishing and will eventually be used up. A star cannot depend upon thermal energy to resist the pull of gravity forever, and a star's final fate depends on whether something other than thermal pressure manages to halt the relentless crush of gravity. |
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More articles:
Astronomy Binoculars - Binoculars.com
Doctor Who rubbishes astrology
Nicolaus Copernicus - Wikipedia, the free encyclopedia
The Antikythera Mechanism
St. Paul’s Cathedral
NASA
Inspired by Maria Mitchell
Generations of women scientists in all of the scientific disciplines have been inspired by Maria Mitchell. Ms. Mitchell was a woman ahead of her time who left an indelible mark on science and the role that women play in scientific research and discovery.
Maria Mitchell was born in 1818. A Quaker couple, William and Lydia Mitchell, had 10 children; Maria was the third child. She attended Cyrus Peirce's School for Young Ladies in her early years, then was taught mostly by her father. After that she was mostly self-educated, but she was the first woman to ever have an advanced degree awarded. It was awarded by Indiana Hanover College in 1853 after she had already discovered a comet, which is named after her. She was also the first woman ever appointed to the Academy of Arts and Sciences.
Maria Mitchell was the most famous American scientist of either sex in the nineteenth century. She was a most remarkable woman who left her mark on astronomy long before women gained the right to vote. In 1847, Maria discovered what we know today as the Comet Mitchell 1847VI, and that was just the first in a long list of accomplishments.
Maria Mitchell is still inspiring young astronomers today. The Maria Mitchell Observatory was established next to her home in Nantucket, Massachusetts, in 1908, and it is still very much operational. There is an extensive public education program, and the observatory sponsors research by undergraduate students. The Maria Mitchell Observatory is funded by the National Science Foundation.
The Maria Mitchell Observatory is also home to over 8,000 historic photographic glass plates. The plates were taken by observatory astronomers and students between 1910 and 1995 and span nearly a century of the Nantucket night skies.
Related Topics: Telescope Jargon,
Mirrors and Lenses, Inspired by Maria Mitchell
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