We have already mentioned what an important part the invention of the telescope has played in man’s exploration of the Universe. Let’s find out the way how can you look at the stars and planets.
More recently, of course, you have seen the value of radio telescopes, satellites, and even manned spacecraft. But in astronomy (the science of the planets and stars) and in geology (the science of the Earth) there are still plenty of discovery to be made by the home scientist with the aid of a few readily available instruments.
If you want to look more closely at the stars and planets yourself you will either need a pair of powerful binoculars or an astronomical telescope. They will give a much greater magnification; that is, they will make the object you are looking at appear much larger.
Let us look at binoculars first. If your family owns a pair or if you are thinking of buying binoculars, you will find that they are usually described by two numbers and that they come in a variety of prices.
The price is dependent upon the quality of the lenses and prisms (these are the pieces that gather the light), on how light in weight they are, and on how much rough handling they will take.
Usually, it is better to buy the very best pair that you can afford, and you should ask for advice on this. The numbers will appear as 8 x 40 or 7 x 50. The first number is the magnification and the second is the diameter of the largest or object lens measured in millimeters.
It is not necessarily better to buy those with the greatest magnification because they cannot usually be used at night and they are very difficult to hold steady without a support. The 7 x 50 binocular is very useful and can also be conveniently used for other hobbies such as bird watching.
An astronomical telescope is more useful for a closer look at the heavenly bodies. (The difference between astronomical and other types of telescope is that the image which you see in the astronomical type is upside down and back to front.)
Of course, this does not matter when you are looking at sometimes like a star, and it means that an astronomical telescope is generally simpler and less expensive than an equivalent terrestrial telescope(one in which the image is the right way round).
Basically, a telescope is an instrument which gathers as much of the light as possible coming from a body. This may be achieved either by a system of lenses, as in a refracting telescope or by large, special type of mirror, as in a reflecting telescope. There are many detailed books on this subject that you can find in your local library, and the manufacturers will be only too pleased to help you.
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