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Telescopes TELESCOPES ALLOW US TO STUDY SPACE FROM EARTH!!! History • • • • Galileo Galilei (1564-1642) 1st telescope invented in Holland in 1609 Galileo learned of this and made his own: small 30X scope Observed the moon and “began” the modern age of Astronomy where measurement was more important than philosophy Galileo noticed • • • • moons orbiting Jupiter phases of Venus craters on the moon sunspots This was strong evidence that Copernicus was right although Galileo wasn’t willing to die for it. The sun was the center of the solar system! Lenses • The lens in your eyes works like a glass lens. The light bends as it goes through a different medium. • Light rays are bent when they intersect glass; a curved surface can produce an image. • In your eye, the image is then focused at the retina. How does this apply to telescopes? • If you had a bigger eye, you could collect more light from the object. This image could be magnified so it stretches out over more pixels in your retina. • In a telescope, two pieces make this possible: • the objective lens (refractor telescopes) or primary mirror (reflecting telescopes) • the eye piece Not everything is visible… www.yorku.ca/eye/spectrum.gif • Many modern day telescopes do not use visible light to collect images. • Radio telescopes, x-ray telescopes and infrared (IR) telescopes have become a staple of modern day astronomy, producing some amazing images. How a telescope works • TELESCOPE: a device that gathers electromagnetic radiation • VISIBLE LIGHT TELELSCOPES REFLECTING TELESCOPE REFRACTING TELESCOPE Uses a mirror to collect light Uses a glass lens to collect light Light bounces off 2 different mirrors light travels in a straight line Newton’s Telescope Galileo’s telescope Famous Optical Telescopes on Earth • Keck Telescope-Mauna Kea Hawaii Mirror is 10 meters wide • Kitt Peak Observatory Tuscon, AZ http://www.noao.edu/outreach/kptour/ RADIO TELESCOPES Show where radio waves are being emitted by objects in space Has a dish & antenna ; Need to very BIG because radio waves are so long Very little interference Very Large Array (VLA) radio telescopes in New Mexico, signals are combined to produce clearer images Problems with earth-based telescopes • Earth’s atmosphere reflects certain wavelengths – x-rays, gamma rays and most UV light is not transmitted by our atmosphere • Earth’s atmosphere blurs images – the bending of light by the atmosphere depends on the temperature of the “air” – “twinkling” (shimmering) effect • “Light pollution” • Solution? Put the telescope in space. HUBBLE Light Absorbed by Earth’s Atmosphere Telescopes in SPACE • Hubble Space Telescope-reflecting telescope – Placed in orbit in 1990 – Collects visible light, infared, & ultraviolet • Chandra X-ray Observatory 1999 • Compton Gamma-Ray Observatory 1991 • Spitzer (infared) 2003 Disadvantages of space-based telescopes • Expensive to launch and maintain • Difficult to repair • Low lifetime Spitzer http://www.jwst.nasa.gov/ Jame Webb Telescope 2014