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Telescope Types and Webb Space Telescope

[This image, known as Webbs First Deep Field, is the first full-color image released from the next-generation James Webb Space Telescope on 7/11/22. It is the sharpest infrared image of the distant universe ever produced, according to NASA. -- Space Telescope Science Institute / NASA, ESA, CSA, STScI, Webb ERO]

- Overview

All celestial bodies emit or reflect light (or electromagnetic radiation). This radiation is spread over a wide range of wavelengths, including (but not limited to) the visible spectrum (i.e. the colors we see every day). 

To help astronomers properly understand what's going on, they need to look at more than just visible light from these objects. To this end, a large number of different telescopes have been built. 

When we look at a star, the light we see is only a fraction of the radiation from that star. So if astronomers only look at visible light in the universe, they can only see a tiny part of the picture. For this reason, astronomers design and build telescopes (some that don't look like telescopes at all) to observe all different wavelengths of light. 

Despite varying sizes and shapes, all telescopes work on the same principle: collect, focus and record radiation. Different telescopes are categorized by the wavelength range or band they are designed to collect: gamma rays, X-rays, UV (ultraviolet), optical, IR (infrared), microwaves or radio. 


- Telescope Types

Most telescopes fall into one of three categories: 

  • refractors (using lenses to refract light to a focal point) 
  • reflectors (using mirrors to reflect light to a focal point)
  • catadioptric or compound telescopes (using a combination of lenses and mirrors )

While you may hear other specific terms for the type of telescope mentioned, such as "Dobson" or "Schmidt-Cassegrain," most other types of telescopes are actually variations of these three basic telescopes. objects, such as Dobson is a reflector or Schmidt-Cassegrain is a catadioptric telescope.


- Picking the Right Type of Telescope for Your Needs

Choose the right type of telescope for your needs. So which oscilloscope is right for you? In most cases, you'll want the largest telescope you can afford, carry and store. However, you may have specific needs that make one range or another more valuable to you personally.

If you want to do deep space observation or wide-angle astrophotography of distant galaxies and nebulae, you may want to consider purchasing a large refractor.

If you want a high degree of flexibility in observing your subjects, a Schmidt-Cassegrain telescope or other compound type telescope will give you a variety of options to determine your observing and imaging experience.

While weighing their benefits and considerations and keeping your budget in mind, you should be able to choose a range that will help you get the most out of the night sky. Our blog on how to use a telescope for beginners includes a step-by-step guide to learn more about telescopes!


- James Webb Space Telescope

NASA’s James Webb Space Telescope has produced the deepest and sharpest infrared image of the distant universe to date. Known as Webb’s First Deep Field, this image of galaxy cluster SMACS 0723 is overflowing with detail. 

Thousands of galaxies – including the faintest objects ever observed in the infrared – have appeared in Webb’s view for the first time. This slice of the vast universe is approximately the size of a grain of sand held at arm’s length by someone on the ground. 

This deep field, taken by Webb’s Near-Infrared Camera (NIRCam), is a composite made from images at different wavelengths, totaling 12.5 hours – achieving depths at infrared wavelengths beyond the Hubble Space Telescope’s deepest fields, which took weeks. 

The image shows the galaxy cluster SMACS 0723 as it appeared 4.6 billion years ago. The combined mass of this galaxy cluster acts as a gravitational lens, magnifying much more distant galaxies behind it. Webb’s NIRCam has brought those distant galaxies into sharp focus – they have tiny, faint structures that have never been seen before, including star clusters and diffuse features. Researchers will soon begin to learn more about the galaxies’ masses, ages, histories, and compositions, as Webb seeks the earliest galaxies in the universe. 

This image is among the telescope’s first-full color images. 


[More to come ...]


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