There are two primary types of telescopes: refracting telescopes (which use lenses) and reflecting telescopes (which use mirrors).

Refracting telescopes use a spherical or parabolic concave primary mirror to reflect incoming (parallel) rays of light from astronomical objects to a focus. Since this focus sits in the path of the incoming light Mark Lowe Jersey , reflecting telescopes have to use one of several different strategies to get the image formed at this focus to the observer.

Isaac Newton developed the first reflecting telescope in 1668, which used a flat secondary mirror, located in front of the primary mirror and set at an angle, to reflect light into an eye piece. Telescopes following this simple design, now known as Newtonian telescopes, are popular with amateur astronomers today.

Another design for a reflecting telescope was published in 1672 by Laurent Cassegrain. This telescope used a primary concave mirror and a smaller secondary convex mirror to reflect light onto the secondary, though a hole in the primary mirror and onto an eyepiece. This design allows for a shorter telescope tube relative to the diameter of its mirror. Telescopes following this design, known as Cassegrain telescopes, are used by amateur and professional astronomers today.

While the first telescopes, including the telescope used by Galileo to discover Jupiter’s moons, were refracting telescopes, most large telescopes used by amateur astronomers and virtually all research telescopes used by professional astronomers are reflecting telescopes. While both kinds of telescopes can collect and focus light from distant objects, mirrors have several advantages over lenses when used in telescopes.

1) Chromatic aberration: As light passes through glass at an angle, different wavelengths (colours) of light will bend at different angles. This is useful when you are trying to separate the colours of light with a prism, but less useful when you are trying to focus a source of white light to a single point. All glass lenses will exhibit chromatic aberration — blurry fringes of different colours at the edges of an object. While careful design can reduce chromatic aberration Lance Parrish Jersey , it cannot eliminate it.

The angle that light reflects off of a mirror does not depend on its wavelength (colour), so reflecting telescopes focus all colours of light to the same point. Thus, they do not experience chromatic aberration.

2) Very large mirrors are easier to manufacture than very large lenses. In addition, to be used in astronomy, lenses have to be perfect throughout. Mirrors only have to be perfect and polished on one side.

3) Since the primary mirror is mounted at the end of a telescope, it can be supported along its base. Lenses used in refracting telescopes can only be supported on their sides. Thus, extremely large lenses (larger than about 1 m) tend to sag under the effects of gravity, distorting the image. This is not a problem for large mirrors.

Why are large mirrors so important? While many people think that the primary purpose of a telescope is to magnify astronomical objects, this is not the case. While telescopes may magnify objects to some extent, their primary purpose is to act as “light buckets” — to collect as many photons from a distant object as possible. Telescopes also allow observers to resolve small details and make sharp images. Both the light collecting ability and the resolving power of the telescope depends on the size of the mirror — in general, the larger the mirror, the more powerful the telescope. What Is a Strategy MMO Game? Breighner Selma
Submitted 2014-02-19 13:42:48 If you have heard the term strategy MMO game and are not specific what this really is then you need to know that MMO holds for huge multi-player online. Which means that the strategy MMO game is an online PC game which has lots of people playing it at one time. You can actually communicate with other players throughout the course of the game.

Maybe you remember back when Dungeons and Dragons was popular. Dungeons and Dragons was a strategy game that had hundreds of individuals taking part in it, but the real enjoyable was had whenever you could really have fun with the other players in real time. A strategy MMO game functions like the aged Dungeons and Dragons in the fact that it has hundreds of participants at once, but the distinction is the fact that online you have the ability to actually connect and interact with all of these players.

During the play of a strategy MMO game lots of people often build relationships with a few of the other players. The other people playing have something in common plus they frequently try out to be online at the same time as their friend so that they can take part in the game together.

Not everyone which you meet during the game will be someone you like. Remember that you will be playing a game and you also perform according to the way you personally would like your experience to be. Some individuals play very fair and honorable games while you will find others that perform backstabbing games where they attempt and use and technique other people that are online. Do not take these manipulations individually as they are not intended personally. The other person does not really know who you really are in real life and they have no personal vendettas. They may be just enjoying a game as well as their style is vicious.

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