Astronomy

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Astronomy

  1. 1. ASTRONOMY Presenter : Khizra Samad 12L-5419
  2. 2. • Astronomy is a natural science that is the study of celestial objects (such as moons, planets, stars, nebulae, and galaxies), the physics, chemistry, mathematics, and evolution of such objects, and phenomena that originate outside the atmosphere of Earth, including supernovae explosions, gamma ray bursts, and cosmic background radiation. • The object of study is the spectrum of electromagnetic radiation, including visible light, which radiates from stars and other hot celestial objects. Spectroscopy can be used to derive many properties of distant stars and galaxies, such as their chemical composition, temperature, density, mass, distance, luminosity, and relative motion using Doppler shift measurements.
  3. 3. Cont.. • The human eye is sensitive to a very small range of wavelengths called visible light. However, most objects in the universe radiate at wavelengths that our eyes cannot see. • Astronomers use telescopes with detection devices that are sensitive to wavelengths other than visible light; this allows astronomers to study objects that emit this radiation, otherwise invisible to us. • Computer techniques then code the light into arbitrary colors that we CAN see. The Hubble Space Telescope is able to measure wavelengths from about 0.1150 to 2 micrometers, a range that covers more than just visible light. • These measurements of electromagnetic radiation enable astronomers to determine certain physical characteristics of objects, such as their temperature, composition, and velocity.
  4. 4. Radio telescope
  5. 5. NASA Infrared Telescope Facility is an example of a telescope that operates only at near-infrared wavelengths.
  6. 6. Origin: • Astronomical spectroscopy began with Isaac Newton's initial observations of the light of the Sun, dispersed by a prism. He saw a rainbow of color. • Just recently, astronomers discovered a distant solar system, 127 light years away with up to seven planets orbiting a Sun-like star called HD 10180. • Like the very first exoplanet 51-Pegusus discovered in 1995, this new system was found using the science of spectroscopy. • Most of the roughly 500 planets so far found orbiting other stars, were detected by the same method.
  7. 7. Cont.. • Spectroscopy — the use of light from a distant object to work out the object is made of — could be the single-most powerful tool astronomers use, says Professor Fred Watson from the Australian Astronomical Observatory. • "You take the light from a star, planet or galaxy and pass it through a spectroscope, which is a bit like a prism letting you split the light into its component colours. • "It lets you see the chemicals being absorbed or emitted by the light source. From this you can work out all sorts of things," says Watson.
  8. 8. Uses • Movement : It helps in determine if an object is moving towards or away from you by the change in frequency of the wavelength. When something moves towards you it compresses the signal wavelength it emits, while if it's moving away from you, it stretches that waveform. • Age of Star : Spectroscopy also tells us the age of a star by looking at the amount of its matter made up of chemical elements other than hydrogen and helium. • Temperature, mass, gravity : fuzziness of the lines, you can work out the temperature, mass and pressure and hence, surface gravity. • The speed at which a star rotates will also show up in the spectrum by smearing of the lines • Is the possibility that one day spectroscopy may be used to find life elsewhere in the universe.
  9. 9. Reference • http://en.wikipedia.org/wiki/Astronomy • http://en.wikipedia.org/wiki/Spectroscopy

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