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The Planet Neptune
Telescope Accessories
When you purchase a telescope -- any telescope -- what you get is…well…a telescope. You don't get anything else, and there are a few "accessories" that really shouldn't be considered accessories.
For example, you really, really need a mount for your telescope. Telescopes need to remain perfectly still while you are observing the heavens. Even the slightest movement isn't satisfactory. It is impossible to hold a telescope perfectly steady, so when you buy your telescope, you also need to buy a mount.
There are basically two types of telescope mounts to choose from: altazimuth and equatorial. The mount that will best serve your needs depends upon how and who will use it. There are two things that you need to remember no matter how much information you gather.
1. Astazimuth mounts cost less that equatorial mounts and they are easier to operate.
2. Equatorial mounts are more expensive than astazimuth mounts, are more difficult to operate, and have many more controls.
Slow-motion controls are another "extra," and both astazimuth and equatorial mounts can be fitted with them.
Filters are another "essential" accessory. For the beginner, just three filters will do; a solar, a lunar, and a light-pollution filter.
A solar filter will cost between $30 and $150 depending upon the filter you choose. Basically, a solar filter allows a user to observe the sun and sunspots because it allows only a small fraction of the sunlight to pass through it. Mylar filters (less expensive) cause the sun to appear as a light-blue color, while glass filters (more expensive) leave the sun in its natural yellow-orange color.
A lunar filter is not expensive, and if you want to observe the moon in any phase other than the first quarter, you need one. A lunar filter will cost about $20.
If you live in a metropolitan area, you most definitely need a pollution filter if you intend to look at deep sky objects. Pollution filters cost between $60 and $150, or even more.
See Also:
Moon Shot, February 20, 2008
Test Your Astronomy Knowledge
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:
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Amazon.com: Moon Shot: The Inside Story of America's Race to the Moon ...
The Medusa Touch - Part 2
For once the answer may really be in the stars.
NASA - Home
Astronomy for Kids
Nicolaus Copernicus
Nicolaus Copernicus first became fascinated with astronomy in 1492 when he enrolled in Kraków Academy (now Jagiellonian University). His professor, Albert Brudzewski, is credited with introducing young Nicolaus to astronomy.
After four years at Kraków Academy, Nicolaus Copernicus's uncle (who paid for his education in hopes that Nicolaus would become a bishop) sent him to Bologna to study civil law. It was there that Nicolaus met Domenico Maria Novara da Ferrara, who was a famous astronomer of the time.
Copernicus gave some friends his Commentariolus (Little Commentary) in 1514. Commentariolus was a short handwritten work that described
his ideas about the heliocentric (sun-centered universe) hypothesis. It was the basis for his later work.
Copernicus feared ridicule from other scientists. He wasn't afraid of what the Church would think of his theories. This fear of ridicule caused him to delay publication of his findings for several years. As a matter of fact, his book, De revolutionibus orbium coelestium (On the Revolutions of the Celestial Spheres) wasn't published until the year of his death in 1543.
It is said that Copernicus was in a coma that had been caused by a stroke when a friend put a copy of his book into his hands. Copernicus awakened from his coma and died peacefully shortly there after.
There are six major parts to the Copernican theory:
1. Motions of the planets are uniform.
2. The sun is the center of the universe.
3. The order of planets around the sun is Mercury, Venus, Earth and Moon, Mars, Jupiter, Saturn, and the fixed stars.
4. Retrograde motion of the planets can be explained by the Earth's motion.
5. Daily rotation, annual revolution, and annual tilting of its axis are the three motions of the earth.
6. Comparatively speaking, the distance between the earth and the sun is small to that of the earth to the stars.
Related Topics: Buying a Telescope,
Galaxies, Binoculars for Astronomy
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