VicToriA :: asked:


I accidently bought a telescope online but that doesn’t matter since I wanted one anyway. Which telescopes are good and which are bad? Any suggestions for me?
Fotar Astral Observer reflector telescope NIB

Features: All Glass Coated Optics Finderscope Interchangeable eyepieces (SR4, H20) 675X Max. Power 900mm Focal Length 114mm Objective lens dia. Equatorial mount

What does this mean?

Debbie

SedativeChunk asked:


I just got a novice level telescope for Chirstmas and I want to know where to look in the sky for planets. I live in the outskirts of Pittsburgh. Are there any websites listing where planets are right now or maps?

Pedro

Will Kalif asked:


The Telescope turns 400 years old this year and in four century  period astronomers and telescope makers have been continually making larger and larger telescopes in order to peer deeper and deeper into the mysteries of the universe. There are currently quite a few enormous instruments in use and there are several next generation telescopes being developed that will dwarf anything currently in use. This article takes a look at some of these magnificent monsters of astronomy.

The largest Refractor telescope

Refractor telescopes are renowned for their absolute sharpness of image because they are composed of very large lenses of compounds of glass which gives them crystal clear images. But they are extraordinarily difficult to make in a large size. Their own weight distorts their shape and makes them unusable above a certain size.

The largest refractor in the world is the Yerkes telescope which has a primary lens that is 40 inches in diameter.  It was completed in 1897 and was built by the famous master optician Alvan Clark. It represents the pinnacle of refractor telescope making and no larger one has since been built in the hundred years since. Reflectors are much more feasible for larger sizes and there are many of this type that are extraordinarily large. It is with reflectors that we achieve very large instruments.  

Reflector telescopes come in two different types. The first type is the single mirror type where a single piece of glass is cast and polished to make the primary mirror. The second type is the segmented mirror where a series of hexagonal mirrors are assembled together into a single large mirror. This type of mirror looks much like the honeycomb from a beehive and this new technology is allowing telescope makers to make instruments larger than ever imagined.

The largest single piece of glass telescope in the world is the Large Binocular Telescope (LBT) in Arizona. It is a telescope composed of two separate mirrors that are side by side and work in tandem. The light from both of them are blended into one single image. Each mirror is 8.4 meters (330 inches) in width and when used together they create the equivalent of a mirror that is 11.8 meters (464 inches) across which is currently the largest light collecting size on Earth. It is located in Mount Graham International Observatory in Arizona.

Segmented mirrors pose technology challenges that have been overcome in the past decade and now these multiple mirror scopes are being built in extremely large sizes that cannot be rivaled by single piece mirrors. Of the segmented telescopes where a series of honeycomb shapes are assembled together into a single telescope there are three different observatories with these largest of mirrors.

The South African Large Telescope (SALT) is the largest primary mirror scope in the world and it has a segmented mirror that is 11 meters (433 inches) across.

The Gran Telescopio Canarias or GTC is located on the island of LaPalma Spain and it has a segmented primary mirror that is 10.4 meters in diameter (409 inches) which makes it the single largest mirror in the world.

The Keck Telescopes are a pair of telescopes located at the Keck Observatory in Hawaii. Each mirror is ten meters (400 inches) in diameter.

Bigger Telescopes to come

There are even larger telescopes currently in the proposal, development, or construction stage.  Technology improvements over the past decade have made a new scale of telescope possible and this new scale is referred to as ELT or Extremely Large Telescopes and it is the next generation to come.  ELT’s are telescopes that are more than twenty meters in diameter which is double the size of existing telescopes.  And this doubling of size gives significantly more than double the light gathering power. Most of these scopes will be of the segmented mirror type but one notable exception is the Giant Magellan telescope which will be composed of seven spherical mirrors constructed together so they act as a single mirror.  This project is scheduled for completion in 2016. It will be located in Las Companas Observatory, Chile.

The Thirty Meter Telescope (TMT), which is currently in development, will be thirty meters across and composed of segmented mirrors.  It is expected to be a telescope of unmatched performance and is predicted to be able to image planets circling other stars.  The current time line for this project is for it to be completed somewhere around 2017 – 2018.

What about the Famous Hubble Telescope?

The primary mirror in the Hubble is 2.4 meters across (94.5 inches) which makes it rather small compared to some of the giants listed in this article. So then why is it the most spectacular telescope ever created? The big advantage the Hubble has over all the other telescopes is that it doesn’t have to peer through the soup of Earth’s atmosphere.  And this advantage is staggering.  That is why the Hubble has brought us some of the most extraordinary images ever recorded.

What comes after the Hubble?

NASA is currently working on its next generation space telescope. It is called the James Webb Space Telescope (JWST). The primary mirror will be 6.5 meters (21.3 feet) in diameter.  Launch is planned for 2013.

Since the invention of the first telescope 400 years ago man has been building ever larger telescopes. The telescopes to come will bring us images of planets around other stars and who knows, they may bring us images of the very birth of the universe we live in.

 

 



Benjamin

Koz Huseyin asked:


No astronomy hobby can go for long, without a good telescope. So, how do you buy the best telescope in the world? And what is the best telescope in the world? In this article, you find how to buy the best telescope in the world.

Telescopes come in all shapes and sizes. They also come with different prices. However, getting the best telescope is not all about buying the best telescope. You see, getting the best telescope is about finding one that meets your needs.

When Galileo made his telescope, and looked at Saturn, he thought Saturn had ears! The truth is that Saturn has a ring around it. To Galileo, he had the best telescope in the world, but to today’s telescopes, it is inferior.

This makes the best telescope, the one that makes you use it the most. After all, if you only look for 5 minutes, and then leave that telescope alone, you will not get the full benefit of telescopes.

A great thought should be on, what you want out of the telescope. For example, for children, a small toy store telescope will be great, however, for an adult, who wants to have a telescope that lasts for years, a more serious investment, will be needed.

This doesn’t mean you have to buy a telescope for an observatory. At this point, you will likely want to factor in costs. How much are you willing to invest in a telescope?

There are several price points to telescopes, and they fall into those that are a few hundred dollars, to those that are $500 to $1,000. Those above $1,000 truly are the best telescopes in the world!

You can expect from a $1,000+ telescope amazing views of the heavens. As the price goes up, more goes into the optics. Not only you get more light gathering power, which is a very important factor with telescopes, you also get a more quality telescope. Orion, Meade, and Celestron are just some telescope manufacturers who make these top quality telescopes that you can buy.

Another factor to consider is space, and where you will keep your telescope. Often this can be overlooked till it’s too late. Telescopes may look like they don’t need a lot of space, however in practice; you will find it needs quite a bit of space.

Buying these telescopes can be done through various places. Telescope and astronomy magazines are one way. However, an easier solution is to buy online. There are many specialist telescope websites, and online stores that only deal with telescopes and astronomy. They can be the best place to find and buy your own best telescope.



Katherine

Mike Kirsten asked:


Telescope is an exciting physics equipment. Buying a telescope is a daunting task for a newcomer. It all depends on your astronomy goals and careers. There is no perfect one which suits all observers in all conditions. You have to look for the features you want in your telescope and select the best one’s according to your requirement.

Selecting the proper type



The refractor type telescopes best suit for watching moon and major planets. Refractor telescopes are long & thin, and known for their sharp, detailed and contrasty images. They collect light through multi-element lenses. If you are just a starter then a small, quality achromatic refractor of 60 to 90 mm aperture would be a good one. The best thing about a refractor telescope is that they are inexpensive, portable and almost maintenance free. A refractor telescope is also useful when you will be mostly observing from city or the surrounding areas where the night skies are lightly polluted.

Reflector telescopes are also known as Newtonian telescopes. They are good for planetary as well as deep-sky viewing. However Newtonian telescopes are more fragile and need more maintenance than others. These telescopes collect light with a curved, concave mirror and with the help of their large apertures, they show fine, highly-resolved images. The reflector scopes are not suitable for terrestrial viewing because they produce an upside-down image.

Catadioptrics use both lenses and mirrors to collect and focus the incoming light. They are also called compound telescopes. Catadioptrics scopes are considered the most versatile telescopes and gives great all-around performance. They use a large aperture in very compact tubes. They show magnificent images of the moon, planets and faint deep-sky objects, when viewed in dark skies away from urban areas. These scopes are best suited for astrophotography. Compared to other two, these scopes have a wide range of accessories available. They can be entirely computer controlled.



Factors affecting the performance of a telescope







Aperture: Telescopes collect light from distant objects and focus it to produce images. The light collecting capacity of a telescope is the most important feature. It is the aperture of scope (diameter of mirror or lens) that is responsible for gathering light. Larger the aperture, the more light gathered, the more you’ll see.

Telescope Mounts: There are three basic mounts for telescopes altazimuth, Dobsonian, or equatorial. Altazimuth is the simplest type of mount, providing up-down, left-right motions. It is mainly recommended for terrestrial viewing and casual stargazing. The Dobsonian mount was basically designed for easy maneuvering of large reflectors of more than six inches. It is a boxy altaz-type mount sitting close to the ground. Equatorial mounts are designed for the purpose of astronomical viewing. These mounts are more expensive and complicated than the altazimuth mounts. With the help of these type of mounts users can track or follow the motion of celestial objects through the sky with a single manual hand control.

Magnification: Magnification should never top the priority for buying a telescope. The quality if image degrades with magnification. Practically 300X is maximum magnification for good quality images. Telescope’s magnification is also known as its power and it is adjusted by changing eyepieces. Ideally there should have been three eyepieces for the magnification of a scope: one low, one medium and one high. Lower powers of 30 - 50X are recommended for observing galaxies, star clusters and nebulae as they are spread over a wide area of sky. For observing the rings of Saturn, Jupiter, studying craters and valleys of the Moon’s surface medium power of 80 - 100X are advised. Higher powers of 150 - 200X allow the astronomers to observe mountain peaks and fine lunar detail, the surface features of Mars.





I am a laboratory analyst by profession working in this industry from last 10 years. I have been running a site http://www.laboratoryequipmentworld.com on laboratory equipments. It includes the largest range of laboratory apparatus and other updated info on market, trade fairs, news, etc.



Clyde

C B asked:


My son wants a telescope for Christmas, but we’re pretty uneducated as to which kind to get. He is 10, but extremely smart and interested. We don’t want a piece of junk, but yet we want something good enough to support his interest. Advice??

Constance

Willard Kalif asked:


The Gregorian Telescope is an interesting design of reflector and it was the first practical design for a telescope that used a mirror. It is still used in modern times but only in very limited circumstances.

Credit for the first reflector goes to an Italian professor named Niccolo Zucchi. He made his first scope in 1616 but the design of his scopes was not very practical. James Gregory was a Scottish Mathematician and Astronomer of the 17th Century and he is credited with having designed the first practical reflector telescope. In 1663 he published this design in his book titled Optica Promota. But he didn’t build the first working model until ten years later with the help of scientist Robert Hooke. It was in this ten year period that Sir Isaac Newton built his famous Newtonian telescope (1670). So the Gregorian telescope predates the Newtonian in design but Newton’s was the first to be built.

How the Gregorian Telescope works

To understand how the Gregorian reflector works we will first take a look at the Newtonian telescope. In the Newtonian a parabolic mirror placed at the bottom of a tube and it focuses light back up the tube to a flat mirror that directs it out the side of the tube to an eyepiece.  The eyepiece is on the side of the tube. In a Gregorian design the parabolic mirror is at the bottom of the tube and it focuses light back up the tube but the second mirror is an ellipsoid and it redirects the light back down the tube to the eyepiece through a hole in the center of the large primary mirror. This type of telescope has the eyepiece at the bottom.

The benefits and shortcomings

Newton’s telescope has one parabolic mirror and one flat mirror while Gregory’s has a parabolic as its primary mirror and an ellipsoid as its secondary. Additionally, Gregory’s primary mirror needed a hole cut in the center of it. These things mean it is a much more optically complex instrument and much more difficult to make. Newton’s design is much easier to make.  This is probably why it took Gregory ten years to make his first working model.

The Gregorian does have some benefits over the Newtonian style scope. The ellipsoid secondary mirror is placed at a point after the focus of the light. This configuration, in conjunction with an eyepiece, provides an erect or right side up image while the Newtonian telescope gives an upside down image. This is a big benefit if you are using the telescope for terrestrial viewing.  And because of this inversion of image after the secondary mirror it allows a baffle to be placed inside the tube. This baffle prevents unwanted light and heat from reaching the primary mirror. This is a very useful tool when a telescope is meant to be used for solar observations where heat is a big concern. For this reason the Gregorian design is sometimes still used for telescopes that will be used for solar observations.

The Gregorian design for a telescope is not used very often in modern times. It has been changed and much improved by the Cassegrain telescope. But the Gregorian does find limited use occasionally as a finder scope that accompanies a larger scope. This is because of the nature of it displaying properly oriented erect images.  And because of its ability to have a baffle inside it is also sometimes used for telescopes built for solar observations.

Gregory’s telescope design is not much used in modern times but it was the forerunner and inspiration for many of today’s telescope designs.

 



Ashley

Will Kalif asked:


Buying a first telescope for you or for someone else as a gift can be a bit tricky if you don’t know a lot about telescopes. This article will guide you through making the right choice based on price, performance, and what your astronomical goals are.

A telescope is a scientific optical instrument. It has lenses or mirrors in it that have to be carefully made to exacting specifications if it is to perform adequately as an astronomical instrument. This can cause problems when it comes to buying a lower priced and subsequently lower quality telescope because these telescopes can underperform or even not perform at all. In order to be guaranteed you will get high performing optics that give you good value for your money you should stick with one of the better known manufacturers of telescopes. I recommend you buy from Orion, Celestron, Meade, or Edmund Scientifics. There are many makers of telescopes that make outstanding telescopes but I have first hand knowledge of these and can vouch for their quality.

Most of these makers of telescopes sell them but you don’t need to buy directly from them. You can find telescopes from these makers on sale at many online sites or retail outlets. So you can stick with your favorite big retailer.

If you are buying a first telescope for a high school student or child your best choice is to buy a 60mm refractor telescope. This kind of telescope is sturdy, easy to use, easy to set, up and gives great performance in the hundred-dollar price range. This type of telescope is also very useful for terrestrial observations, which makes it versatile. I would vary from this rule of thumb if you are getting a telescope for someone that spends a lot of time hiking and camping and they are looking for something easily toted along. A 60mm refractor can be a bit impractical for camping and hiking because of its size. In this case I recommend you get either an astroscan from edmund scientifics or the backpack observatory from the Meade Corporation. Both these telescopes are a bit more expensive but much more compact and easy to tote around.

If you are buying a telescope for someone that knows a bit about astronomy or maybe already has a telescope you might consider sitting down with him or her and discussing needs and wants. Telescopes vary widely in price, style, type and ability and an amateur astronomer probably has some definite wants and goals. But as a rule of thumb for a person that already is interested in astronomy they probably are looking for a reflector or catadioptric telescope because these types of telescopes give significantly more light gathering power than the refractor when you weigh the price. A five-inch refractor telescope will cost you anywhere between three and four thousand dollars! Yet you can get a reflector or catadioptric with a massive eight or ten inch mirror for a few hundred dollars. This massive increase in size gives the amateur astronomer a significant improvement in what he or she can see in the night sky.

If you are looking to purchase something in a moderate price range (500-1,000 dollars) you should consider getting a catadioptric telescope in the Schmidt Cassegrain style. This type of telescope gives you superior performance, maximum light gathering power, and quality of instrument that will last you a lifetime. This kind of telescope now often comes with a motorized computer with a database of thousands of celestial object that allows you to find things at the touch of a button. It is also a folded optics telescope so it is compact and reasonably easy to tote around. They are suitcase sized and many of the leading manufacturers often make the suitcase to go with it.

In summary if you are buying for a child, teen, or first time telescope owner you should get a 60mm refractor because it is easy to use, easy to set up, durable and entry level priced around one hundred dollars. If you are buying a telescope for someone that is seriously interested in astronomy you should consider a reflector in the six-inch to ten-inch range. This will give you maximum light gathering power for your dollar in the range of three hundred to five hundred. If you are looking to buy something of heirloom quality that will give you a lifetime of superb quality you should consider an eight-inch catadioptric Schmidt-Cassegrain telescope which will cost between five-hundred and a thousand dollars.



Frances

Shadow15 asked:


I’ve noticed that people have been able to record things by camera through their telescope, I am asking how does someone do this?

Brett

Blue Bear asked:


I’ve gone through 3 telescopes in all of my life and have never been able to reap the rewards of having one as other’s have. I always have trouble focusing, etc. Do you have any advice on how to effectively use a telescope?

Ellen