Before we look at our telescopes for sale let us consider different instruments and how your telescope works?
Our telescope can show you wonderful things and take you incredible distances across the universe. To understand it, you must know that a telescope is a “creature of light” Light is the medium of vision, one of the most important of the five senses (vision, hearing, touch, smell, and taste) that we use to gather information about our environment. On a clear night, some of the light from the heavens will reach your telescope, and your telescope will “process” this light to direct an image to your eye. Here is how that light works –
The Signature of the Universe Visible light is a form of energy called electromagnetic (or radiation (which also includes invisible energy, such as radio waves and X rays). Unlike other forms of radiation, our eyes recognize only visible light. Light moves in waves, something like ocean waves. Stand on the shoreline with a stopwatch and time the number of waves that reach the shore every second. If one wave reaches the shore every second, the wave frequency is one wave per second. Next, stand in the surf with a yardstick and try to measure the distance between a wave crest and the crest of the wave following it. This distance is called the wavelength.
The least energetic kinds of E.M radiation, those with the longest wavelengths, are microwaves and television and radio waves. Like infrared light, these waves are not energetic enough to penetrate human skin.
The least energetic kinds of radiation, those with the longest wavelengths, are microwaves and television and radio waves. Like infrared light, these waves are not energetic enough to penetrate human skin. How Does the Light from Space Originate? All of the different types of light (visible and invisible) are energy. No matter what their wavelength and frequency, all the photons traveling through space have a common origin.
Deep inside all stars (including our Sun), pressures and temperatures are high enough that hydrogen atoms can be forced together or fused. In this thermonuclear reaction, a small fraction of the mass of reacting particles is con- verted into energy. This energy comes out in the form of gamma rays. As the gamma rays rise toward the star’s surface, they react with various atoms in the star’s interior. By the time the photons reach the star’s surface, much of the thermonuclear energy originally in the form of gamma rays has been converted through these reactions into X rays, ultraviolet light, visible light, and the other forms of light in the spectrum. Light in the Earth’s Atmosphere after escaping from the Sun (or another star), a light photon streaks through space at 300,000 kilometres (186,000 miles) per second. It may reach your eyes directly, or it may be reflected from the surface of a planet or satellite. When a stream of photons strikes our planet’s atmosphere, several things happen. Some of the photons are immediately reflected into space by the Earth’s atmosphere. Atoms in the Earth’s upper atmosphere (the ionosphere) remove most of the gamma rays and X rays from the photon stream by absorbing them.
About 20 Kilometres (12 miles) above the surface of the Earth is an atmospheric layer known as the stratosphere. In the stratosphere, most of the ultraviolet light photons are absorbed by an unusual form of oxygen called ozone. In recent years, an increasing number of people have become concerned about possible deterioration of the ozone layer. If the ozone layer continues to disappear, the increased number of ultraviolet rays reaching the ground will make a summer visit to the beach hazardous to your health!
Most of the Earth’s water vapor is in the lowest atmospheric layer, called the troposphere. Here, just above the ground, water vapor and a gas called carbon dioxide absorb most of the infrared radiation.
In the lowest portion of the atmosphere, some of the visible light photons are scattered, or reflected, by atmospheric gases. Because blue photons are more easily scattered than red photons, the sky is blue when viewed from the Earth’s surface. From the viewpoint of astronauts above the atmosphere, the sky is black.
The colour of the setting Sun:
You can get a good feel for the variable-scattering effect of the Earth’s atmosphere by observing the colour changes of the Sun as it sets. By glancing indirectly in the direction of the Sun when it is high in the sky, you have of course noticed our star’s predominant yellow colour. As the Sunsets, its light travels through more of the Earth’s atmosphere and therefore is more affected by scattering. Therefore, the Sun seems redder just before it sets (or after it rises) than when it is higher in the sky.
Of course, the blue photons scattered by the atmosphere do not just disappear. While scattering makes the Sun “redder,” the day sky gets “bluer” but even those photons that reach the Earth’s surface are not unaffected by their passage through the Earth’s atmosphere. When light leaves one medium and enters another (say from space into or air into water), its velocity changes and its path is bent, or refracted. Light slows down as it goes from space into it slows again if it enters water or glass.
One way of observing refraction is to pitch coins into an aquarium or swimming the trajectory (or path) of a coin seems to change when it enters the water. If you have an aquarium, notice how a fish’s position seems to change when it is viewed from above and from the side.
How Your Telescope Works:
If you have a good sky view to the western (or eastern) horizon, you might be able to observe the setting (or rising) Notice how the Sun’s image seems to spread out from a sphere into a when it is close to the horizon. This effect occurs because light from the part of the Sun near the Earth’s horizon travels through more atmosphere than light from the parts of the Sun that are higher in the sky. Light rays near the horizon experience more bending by refraction.
A refractor is a telescope that uses lenses alone to magnify objects. It is a modern version of the first astronomical telescopes used by Galileo. The large objective lens collects light from a distant object and delivers this light beam to the eyepiece, the lens or set of lenses at the hack of the tube. The eyepiece then focuses the light on your eye. If the image is properly focused and the optics are properly aligned, you will observe a bright and distinct image of the celestial object.
A Newtonian reflector, the earliest type of reflecting telescope, uses lenses only in the eyepiece. Most of the work is done by mirrors. Light is collected by a curved Primary mirror. A flat secondary mirror, which is much smaller than the Primary mirror, directs the collected light to the eyepiece.
Early reflectors were large and hard to work with. in 1672, an obscure French man named N. Cassegrain designed are reflecting telescope with a curved secondary mirror. Many large and small modern telescopes use Cassegrain’s approach to bend the light further. These telescopes are more compact than many Newtonians of the same primary mirror diameter.
Many astronomers will advice the most important factor of buying a telescope is the aperture, bigger the aperture the more light is absorbed and the clearer the image. This was true years ago however manufacturing methods have advanced significantly, and you can get surprisingly good performance from a small aperture telescope. With this industry you really do get what you pay for, as you spend more the quality of image increases.
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