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Famous Meteorites
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:
Mystery Heavenly Body Discovered, a front page story
About Telescopes
The Planet Neptune
Adams and Leverrier predicted the existence of the planet Neptune back in 1845. Neptune is very difficult to observe from the earth because of (1) the distance, and (2) the earth's atmosphere. The closest and best look that we have had at Neptune was provided by the Voyager 2 flyby in 1989.
Neptune is the most distant planet from the sun. It was once believed that Pluto was a planet Pluto beyond Neptune, but astronomers have declared that Pluto is not a planet but one of many dwarf planets in our solar system.
Neptune has a diameter that is about four times larger than earths. Computer models suggest that Neptune has a rocky core that comprises about 15 earth masses at the center, but there is no confirmation of this theory. Neptune has a rotation period of about 16 hours. Neptune has an internal heat source, and it produces about 2.7 times more heat than it absorbs.
Strong winds, bright, high-altitude clouds, and two large dark spots attributed to long-lived giant storm systems were reveled by the 1989 Voyager flyby. Wind speeds are as high as 739 miles per hour. The larger of the two dark spots that Voyager reveals is called the "Great Dark Spot."
Neptune's rings were first detected from Earth in 1983, but no real study could be conducted at that time. It wasn't until the data supplied by the Voyager 2 flyby was available that any determination about the rings could be disseminated. There are two bright rings and two fainter rings. The rings rotate in the same direction as Neptune, and they are all close to the equator.
Triton and Nereid are the two large moons of Neptune and are visible from Earth. Voyager 2 discovered six more moons, and one of them is actually larger than Nereid; but it is difficult to see because it orbits so close to Neptune. |
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More articles:
Amateur Astronomy Magazine
Planting by the Moon Phases - by E. A. Crawford
Astronomy For Kids
Mystery Heavenly Body Discovered, a front page story
Short focal Length Lense and Deep Sky Objects?
Guide to Buying a Telescope
Our Sun
There is nothing remarkable about our sun in the scheme of things. It is very similar to millions of other stars (and our sun is a star) in the universe. You might even call our sun an "average" star.
The energy source for our sun is nuclear fusion. If the total energy output of the sun for just one second could be captured, it would provide the United States with enough energy at the current level of usage for nine million years.
There is a hard core at the center of the sun. The core is so dense and the sun is so large that energy released in the center of the sun takes 50 million years to reach the surface. That means that if the sun suddenly stopped producing any energy at all at the core today, it would be another 50 million years before we noticed it here on earth.
Our sun has been producing radiant and thermal energy for the last four or five billion years. There is enough hydrogen for it to continue producing energy for at least another hundred billion years. In about 10-20 billion years, the sun will begin to expand. It will engulf the closest planets (including Earth), and then it will be a giant red star. In another few billion years after that, our sun will become what is known as a dwarf star.
Most people think of the sun as this large (huge), constant featureless fireball in the sky. The large part is right, but the constant (or steady) and the featureless parts are all wrong. Sunspots are a feature of the sun that was first noted by Theophrastus about 325 BC. A moderate-size sunspot is about the size of Earth. Sunspots come and go over a period of days or weeks.
Related Topics: The Moon Shot,
Planting by the Moon, Telescope Accessories
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