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Archiverr Resource Center ASTR 370: Introduction to Astronomy Lab Astronomy Lab - Study Notes About the Course An introduction to the astronomical concepts and procedures that are used in the laboratory. Operation of the telescope and measurements of star magnitudes, spectral lines, and the movements of the sun, moon, and planets are included. Session: 2022 Units: 4 Study Note Title: Telescope Operation The technology we use to learn about the universe, such as telescopes, is discussed in this study notes. Tycho Bhrahe's telescopes were the first examples of telescopes used to study the cosmos before the telescope was invented. It wasn't until later that the telescope was developed that humans could view farther and more dim things than ever before. Thanks to technological advancements, we've learned more than ancient astronomers could have anticipated, and computers have allowed us to study the data even further.
Telescopes As we have seen, the optical spectrum is just a small portion of the whole spectrum. We should develop telescopes to observe the various sections of the spectrum to take advantage of whatever information we can glean from the variety of light sources available to us. This is precisely what we do in the construction of radio telescope arrays. Optical Telescopes Images can be formed through reflecton or refraction. Reflecton mirror Refracting lens Image formation (You can see that the object turns out upside down (or inverted) by all the bouncing around, but since we're usually looking at something like a star, or a planet, we don't usually care about it being upside down (some telescopes can fix the inversion if you want). Reflectng and refracting telescopes (Telescopes that use mirrors are called reflectng telescopes, and those that use lenses are called refracting telescopes. Both telescopes have good and bad points, but most of the best telescopes are reflectors. We'll get into the reasons why soon.) Modern telescopes are all reflectors:
Computers can sharpen photos using image processing. The resolving power and light-gathering efficiency of the Hubble Space Telescope are nothing short of amazing. It can view items that no other telescope can (but a new telescope is on its way!). M100, a spiral galaxy, is seen in the photos above. When the Hubble was first launched, one of the greatest ground-based images was obtained. The second image is of the same galaxy as the first, as captured by Hubble! Although Hubble's field of view (the area it can see with the telescope) is less, you can still see the fine details that Hubble is capable of. The Hubble provides a crisper picture in exchange for a limited field of vision. The Hubble Space Telescope uses several instruments. High-resolution images from the Hubble Space Telescope. Size of Telescope There are multiple observatories on Mauna Kea, not just one. This inactive volcano's lofty elevation makes it an ideal location for astronomical observations. At 14,000 feet, the atmosphere is much less dense, reducing the likelihood of visual distortion. Light-gathering power: This allows us to clearly view the galaxy's dimmer regions.
The square of the mirror determines the amount of light reflected. Part (b) of the image was captured with a telescope two times as large as (a). As a result of the use of many telescopes, The highest point in the United States is Mauna Kea. High-Resolution Astronomy Solutions: o Put telescopes on mountaintops, especially in deserts. o Put telescopes in space. o Use active optics – control mirrors by bending them slightly to correct for atmospheric distortions. It's possible to use computers again and a system called adaptive optics to cut down on the atmospheric effects - with these systems, ground-based astronomy can be even better than the Hubble space telescope! Radio Astronomy Radio telescopes: Similar to optcal reflectng telescopes Prime focus
Resolution will be that of a dish whose diameter = largest separation between dishes. Interferometry requires preserving the phase relationship between waves over the distance between individual telescopes. These telescopes can get radio images whose resolution is close to optical. Interferometry can also be done with visible light, but it is much harder due to shorter wavelengths. This is CHARA array up at Mount Wilson, above Los Angeles. It’s used to research exoplanets (planets outside our solar system), among other things. Space-Based Astronomies Infrared radiation can image where visible radiation is blocked by interstellar mater or atmospheric partcles. Infrared telescopes can also be in space or flown
