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TelescopesNotes
Electromagnetic Radiation
•Energy that travels through space in the form of waves is called Electomagnetic Radiation. EM radiation does not require a medium.
•All of the various types of EM radiation from the longest wavelengths to the shortest wavelengths is the EM Spectrum.
•The only radiation from the the EM spectrum that we can see is called visible light.
Types of Telescope•Telescopes are instruments that
collect and focus light and other forms of EM radiation.
•A telescope that collects and focuses visible light is called an optical telescope. The two major types of optical telescopes are refracting telescopes and reflecting telescopes.
Types of Telescopes
•A refracting telescope uses convex lenses to gather and focus light.
•Galileo is credited with having used a refracting telescope first to view the sky.
Types of Telescopes
•A reflecting telescope uses a curved mirror to collect and focus light. The largest telescopes are reflecting telescopes.
•In 1668, Isaac Newton is credited with building the first reflecting telescope.
Types of Telescopes
•A radio telescope is a device used to collect radio waves that come from objects is space. Most radio telescopes have large, curved surfaces like dishes.
•Radio telescopes can combine multiple dishes to form one larger dish.
The Very Large Array (VLA) in New Mexico is
a set of 27 radio telescopes that can be
maneuvered and combine together to
form one radio telescope 25 kilometers in
diameter.
The Arecibo radio telescope in Puerto Rico was built into a natural bowl in the ground. It is 305 meters in diameter and is the largest single
radio telescope in existence.
Types of Telescopes
•Telescopes have also been developed to look at all parts of the EM spectrum.
•Telescopes can now see into the infrared, microwave, X-ray, ultraviolet, and Gamma rays of the EM spectrum.
Observatories•An observatory is usually a building
that has one or more telescopes. Some observatories are not in buildings, because they are in space.
•Why would we want to have observatories in space? What does Earth have/not have that would make telescopes on the surface undesirable?
The Hubble Space Telescope was put up in 1990 and is
intended to last until 2014. It has a nearly 8 ft-wide
aperture (opening) and has taken the most clear pictures
of space.The James Webb
Space Telescope will replace the Hubble. It will have a mirror of nearly 21 feet and is intended to look far
enough into the universe to see
galaxies, stars, and even planets in the process of forming.
Observatories
•Because it is very expensive to put observatories into space, many telescopes are still Earth-bound.
•But because of light pollution, air pollution, and atmospheric interference, where is the best place to install these large telescopes?
The Keck observatory is a two-telescope
observatory at an elevation of 4,145 meters at the summit of Mauna
Kea in Hawai’i. Each mirror is 10 meters
across, making them the 2nd largest optical
telescopes on the planet.The Giant Magellan Telescope will eventually
be the world’s largest optical telescope. It’s
mirror will have an 24.5 meter diameter and will sit at Las Campas Peak, Chile at 2,550 meters
above sea level.
http://www.nature.com/news/specials/hubble/slideshow.html
http://store.discovery.com/telescopes/index.php?
v=discovery_telescopes&nvbar=Telescopes
http://media.skyandtelescope.com/documents/AboutScopes.pdf
http://stellarium.org/