Telescope | Eyepieces

Telescopes are devices that are used to view the distant objects. They find its use in astronomy and physics. It enables you to view the distant objects by magnifying them. There are many types of telescopes and their prices vary according to the specifications. Many accessories are also available that can be used in conjunction with the telescopes. Small telescopes that are used as toys are also capable of viewing some objects around 50 meters away.

Principle in which the telescope works

The principle in which the telescope works is very simple. There are two lenses that make up the task of viewing the objects that are at a distance. One of the lenses picks up the light from the object viewed and makes it available at a focus point. Another lens picks up the bright light from the focus point and spreads it out to your retina so that you can view. The lens that picks up the light from the object is called the objective lens or primary mirror. The lens that picks up the light from the focal point is called the eyepiece lens.

Factors that affect the viewing of the object

The capability of the telescope to collect the light from the object that is viewed and the capability to enlarge the image are the factors that affect the efficiency of the telescope. The capability to collect light from the object depends on the diameter of the lens or mirror, which is otherwise called the aperture. The larger the aperture the more the light it can collect. Enlarging of an image depends on the combination of the lenses that are used. The eyepiece in the telescope performs the magnification.

Some of the world's largest optical telescopes in operation

We say a telescope to be larger based on the aperture size. Based on this we can say that Keck and Keck II are the largest telescopes in operation with an aperture of 10 meters diameter. The Keck telescope is composed of 36 mirror segments. This is located at Mauna Kea, Hawaii. The next largest is Hobby-Eberly located at Mt. Fowlkes, Texas which has an aperture of 9.2 meters. You can get a list of the largest optical telescopes at here.

Choosing your telescope

The choice of the telescope largely depends on what you want to observe. You can choose compound telescopes and refractor type of telescope for viewing through the urban skies. For the rural skies, you can use compound telescopes and reflectors. They are better than the refractors type of telescopes. Each type has its own advantages and disadvantages. Hence, many people have different telescope for different purposes.

By: David Chandler
Article Source: Article City

It is actually quite easy to make a timeline with regards to the invention of the telescope as well as how it has evolved over the years. Much has been written about the telescope and good records have been kept with regards to new technologies and inventions. Basically, the telescope timeline looks something like this:

1609 - Galileo first invented the telescope. Though it was crude, it still did the trick and allowed him to look into space for the very first time other than with the naked eye. Galileo's telescope was a reflecting one causing light to bounce off a mirror when looked at through a lens.

Mid-1600's - Johannes Keplar came up with the idea of a refracting telescope that would widen the field of view as well as improve the quality of the image. He did this by changing the shape and the placement of the lenses, but doing this caused little circles of color that would surround bright objects - chromatic aberration.

Late 1600's - As the century began to draw to a close, telescope makers were realizing that with a bigger lens, you could see much more. With a bigger lens, the telescope had to be bigger to accommodate it. Eventually, telescopes were being built that we as long as a hundred feet!

It was at this point in the telescope timeline that Sir Isaac Newton began to change telescope lenses so that there would be no chromatic aberration. He also found a way to add mirrors to improve images without having to make the telescope longer. This appealed to people as Newton's telescope was small but had the same power as the larger ones.

Mid-1800's - The first photographic telescope is introduced. John William Draper found a way to focus the Moon's image on a light-sensitive photographic plate. He used a clockwork device to keep the light in place even as the Earth rotated and the moon moved through the sky. After an exposure of 20 minutes, he had taken the first ever photograph of the moon! After the introduction of the photographic telescope came about, we were able to see the skies up close and personal. And what a great accomplishment!

The early timeline of telescopes shows that many advances were made even before we advanced into what we think of as modern times. Since the 1800's, so many advancements were made in the field of producing telescopes that documenting each and every one would be able to fill up pages and pages of text.

Suffice it to say that now we are graced with telescopes that can see even the minutest parts of Saturn's rings and even realize that Pluto is just a little too small to be a real planet. The timeline of telescopes will continue. All we have to do now is sit back, watch, and document the advancements.

You can visit here for more about telescopes and how this can be a fun and rewarding hobby for the whole family.

By: Elijah Kim
Article Source: Ezine Articles

Hubble Space Telescope launched in 1990 and has been an invaluable source of information to astronomers and scientists throughout the world. By it orbits its way around the earth once every 95 minutes, it continues to gather more knowledge about not only our galaxy but the ones beyond as well.

A timeline of Hubble Space Telescope History:

1924 - Edwin Hubble looked up into the night sky to disprove the theory of a single galaxy. He discovered that the universe was filled with other galaxies rather than just gasses and dust. He prove that our universe was continuing to grow and expand. However, he did not have the suitable of the tools to use, so his knowledge was still somewhat limited although his vision was far-reaching.

1924-1983 - the concept of a Large Space Telescope (LST) was conceived, designed, revised, developed and implemented. To honor the man who started it all, in 1985, the LST was renamed the Hubble Space Telescope.

1990 - The Hubble Space Telescope was sent into orbit, after delays with its launch, due to conflicts with the launch of the space shuttle.

1994 - the telescope took pictures of a comet collision, and detailed photos of Pluto, as well as giving us a greater knowledge of Neptune and Uranus.

1995 - the Hubble took pictures of the “birth” of a star as it developed from interstellar clouds.

1996 - Photos from the Hubble Space Telescope show that quasars are actually nuclei which illuminate when a black hole uses energies from surrounding gases and stars.

1997 - Black holes are bigger than the sun, proved by the picture taken by the Hubble.

1998 - The Hubble take the most detailed pictures of the planets in our solar system.

2004 - The Hubble Space Telescope was able to document in pictures how, when, and why stars die and using the Hubble Ultra Deep Field technology, to take pictures of the expanding universe unlike any that had previously been taken. It also took pictures of Mars when it was closer to Earth than it had been in 60,000 years.

2005 — Took pictures of a comet with a projected piece of equipment from the Hubble Space Telescope.

Future Developments—The Hubble Space Telescope’s mission is scheduled to end with this decade. Astronauts will go up, make repairs and assess the future usefulness of this tool in deep space discovery and a decision will be made about whether it should be discontinued or remain in service. But, no matter what decision is made, this telescope has been an amazing resource for a broader understanding of space and its limitless possibilities. Thank you, Mr. Hubble.

By: Guy Scott
Article Source: Article City