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The Universe

The Universe. Formation of the Universe. How do we study the formation of the universe? https://www.youtube.com/watch?v=QUpWCRadIIA Solar Nebular Theory http://www.universetoday.com/77525/nebular-theory/#ixzz2WBvmHTgK. EARLY ASTRONOMY. Aristotle and Ptolemy: Early Astronomers

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The Universe

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  1. The Universe

  2. Formation of the Universe • How do we study the formation of the universe? • https://www.youtube.com/watch?v=QUpWCRadIIA • Solar Nebular Theory • http://www.universetoday.com/77525/nebular-theory/#ixzz2WBvmHTgK

  3. EARLY ASTRONOMY • Aristotle and Ptolemy: Early Astronomers • Believed in the GEOCENTRIC Universe. • Sun and planets revolve around the Earth. • Roman Catholic Church agreed and declared it true. • Anybody against it was a HERETIC.

  4. MODERN ASTRONOMY • Copernicus (1473 – 1543) and Galileo (1594 – 1642) • Believed in a HELIOCENTRIC Universe. • Copernicus used his observations to discover the “Sun Centered” Universe. • He did not publish his findings until he was dying. • Galileo used his observations to support the Copernican theory. • He did not publish until very old and was put under HOUSE arrest as a heretic.

  5. MODERN ASTRONOMY • Johannes Kepler: (1571 – 1630) • Used precise observational tables to study planetary motion mathematically. • Came up with the 3 Laws of Planetary Motion. • Kepler’s Laws supported the HelioCentric Universe. • His evidence showed the orbits of planets to be ELLIPTICAL(oval) in shape.

  6. The Universe from Earth • With the naked eye we can see about 2000 stars from Earth. • The Milkyway is a band of light making its way across the night sky. • What is it? It is our view of our galaxy. Milkyway

  7. Night Sky from Earth • The night sky is familiar, but few people look closely at what is going on. Orion Constellation Rising

  8. Night Sky from Earth • Why do stars rise and set? • What is important about the North Star? • What are constellations?

  9. Night Sky from Earth • Why do stars rise and set? • The stars APPEAR to rise in the East and set in the West, just like the Sun. • Reality . . . the Earth is ROTATING on its axis. • More Reality . . . the stars stay STILL (relatively) • Earth rotates about 1000mi/hr • Earth Revolves around the Sun at 30km/sec

  10. Night Sky from Earth • What is the North Star? • The North Star is just an AVERAGE star that happens to be nearly in-line with the Earth’s axis. • Reality . . . It is NOT the brightest star. • The name of the North Star is POLARIS. POLARIS

  11. Constellations • Constellations are groups of stars that make up mythological pictures. • There are 88 official constellations • They represent REGIONS of the sky • There are two kinds of Constellation Groups. • Circumpolar Constellations • Located close to North Star and can be seen all year. • Seasonal Constellations • Farther from North Star so only can be seen for short periods of time. (seasonally) • Caused by Earth’s REVOLUTION around the Sun.

  12. Circumpolar Constellations • 5 Constellations can be seen all year round from the Northern Hemisphere. • Ursa Major (Big Dipper) • Ursa Minor (Little Dipper) • Cepheus (the King) • Cassiopeia (the Queen) • Draco (the Dragon)

  13. Finding North • How to find North. • Find the Big Dipper. • Follow the two end “Pointer” stars to Polaris.

  14. SEASONAL CONSTELLATIONS • Seasonal Constellations • Constellations that APPEAR to rise in the East and set in the West throughout the year. • The constellations that are visible change as Earth revolves around the Sun. • Example: Orion

  15. Winter Circle Constellations

  16. Spring Constellations

  17. So what are you looking at? • What are you ACTUALLY SEEING? LIGHT

  18. WHAT IS LIGHT? • Light is really just the visible part of electromagnetic radiation produced by stars like our Sun. . . • OKAY. . . Then what is electromagnetic radiation?

  19. Electromagnetic Radiation • Definition: Energy that is radiated in waves and is emitted by all objects like stars including our Sun. • Best known as VISIBLE LIGHT but includes radio waves and ultraviolet waves too. Rainbows May Include Very Unusual eXamples of Green

  20. Light and EM Radiation • Electromagnetic Radiation can travel through empty space (without molecules). • They travel as vibrations in electrical and magnetic fields • All forms of EM radiation travel at the SAME SPEED. • Speed of Light = 300,000 Km/sec • Speed of Sound = 340 m/sec (.340 km/sec) Click here Animation: Interaction of vibrating charges

  21. Light as Waves • A wave is just a disturbance in some medium (water, air, space) • A wave travels through a medium but does not transport material • A wave can carry both energy and information

  22. Wave Terminology • Wavelength - distance from peak of one wave to peak of another. • Amplitude - the height of the wave compared to undisturbed state. Think volume with sound waves and brightness with light • Frequency - the number of waves passing in a given amount of time

  23. Wave Terminology • How do these terms relate to one another? • As wavelength DECREASES . . . • Frequency • Energy • Danger Increases Increases Increases

  24. Electromagnetic Spectrum • Electromagnetic Spectrum—name for the range of electromagnetic waves when placed in order of increasing frequency • Click here (Animation—Size of EMwaves)

  25. The Electromagnetic Spectrum • Human eyes see the visible part of the spectrum • Longer wavelengths includesinfrared light, microwaves, and radio • Shorter wavelengthsincludesultraviolet light, X-rays, and gamma rays • All of these travel at the speed of light. • But, they have different wavelengths.

  26. Wavelengths of Light - Visible • We break white light into red, orange, yellow, green, blue, indigo, and violet (ROY G BIV) • Red is the LONGEST • Violet is the SHORTEST • Visible light is the Smallest section of the EM Spectrum

  27. Astronomers use different wavelengths of light to study objects in space because: • We get a different view • and lots more information. • Some objects are only • visible at certain • wavelengths

  28. The Sun at Different Wavelengths Visible Ultraviolet X-ray X-ray

  29. TELESCOPES • Optical Telescope: Used to see VISIBLE light from objects in space. • Galileo: designed small 30X scope • Observed the moon and “began” the modern age of Astronomy

  30. Optical Telescopes • Refracting telescope • objective lens bends light • Reflecting • objective mirror reflects light Objective lens Objective mirror Reflecting Refracting

  31. Problems with Earth-based telescopes • Earth’s atmosphere reflects • x-rays • gamma rays • most UV rays • Earth’s atmosphere blurs images • Atmosphere bends light. • “twinkling of stars” (Caused by movement of air) • “Light pollution” caused by man-made light • Solution? Put the telescope in space.

  32. Advantages of Space Telescopes • Can collect EM wavelengths that do not penetrate the Earth’s atmosphere • Gamma rays • X-rays • Most Ultraviolet waves • Can collect all EM radiation without disruption from Earth’s atmosphere • Images MUCH sharper

  33. Disadvantages of space-based telescopes • Expensive to launch and maintain • Difficult to repair • Short lifetime

  34. HUBBLE SPACE TELESCOPE • Launched in 1990 • Mirror error fixed ‘93 • 15 yr life expectancy • Going on year 23!! • 96 minutes for 1 orbit around Earth

  35. HUBBLE IMAGES

  36. SPECTROSCOPY-Composition • Spectroscopy: Study of Star Spectrums. • Can be used to determine: • COMPOSITION of a star • TEMPERATURE of star • DIRECTION OF MOTION of star • Types of Spectrums: Continuous Line Spectrum Incandescent Bulb Bright Line Spectrum Fluorescent Bulb Dark Line Spectrum Sun and Stars

  37. SPECTROSCOPY - Composition • Spectral Lines • Each element has its own set of Spectral Lines. • We call them “Fingerprints” because each is different. Fluorescent Light Spectrum

  38. SPECTROSCOPY- Composition • Chemical Composition – Study Star light • Spectroscopy : • Studying the spectrum of a star. • Comparing spectrums of known elements to the spectrum of a star to determine what elements are in it. • In general stars are 75% H and 24% He and 1% or less everything else - but we can still do it pretty well

  39. SPECTROSCOPY - Temperature • Spectroscopy • How do you determine TEMPERATURE of a star? • By looking at the color of the star • By looking at the stellar spectrum • What color indicates HOT? • Blue = Hot • Red = Cool • Which stars are hottest and which are coolest in image? Top ones HOTTER, bottom ones COOLER

  40. Spectral Lab Summary Green Yellow Red Blue • Looking at these stellar spectrums, what properties of the star can you tell us? • What wavelength it produces the most • Its approximate temperature • What color it will appear Hot Cool

  41. SPECTROSCOPY - Motion • Doppler Effect: • The apparent lengthening or shortening of wavelengths due to motion. • Sound waves: Motion • Towards = shorter waves = HIGHER pitch • Away = longer waves = LOWER pitch • Light waves • Towards = shift to Blue • Away = shift to Red

  42. Doppler Effect • https://www.youtube.com/watch?v=Djz_rtnXSfY • https://www.youtube.com/watch?v=yWIMWqkcRDU&feature=related • https://www.youtube.com/watch?v=Tn35SB1_NYI • https://www.youtube.com/watch?v=Bx0SMevn-0c

  43. SPECTROSCOPY - Motion • Motion of Stars • Is a star moving TOWARDS us or AWAY from us? • How can we tell? • Spectroscopy: Studying star spectrum tells us direction of motion • Moving AWAY • Spectral lines of a star shift towards the RED end of the spectrum. • Called RED SHIFT • Moving TOWARDS • Spectral lines of a star shift towards the BLUE end of the spectrum. • Called BLUE SHIFT

  44. SPECTROSCOPY - Motion • Red Shift • Star moving AWAY. • Wavelengths LENGTHEN. • Spectral lines of star shift towards the RED end. • Blue Shift • Star moving TOWARDS. • Wavelengths SHORTEN. • Spectral lines of star shift towards the BLUE end.

  45. PROPERTIES OF STARS • There are 4 properties of a star that we measure. • Distance • Chemical Composition • Temperature • Magnitude Measured in Lightyears (ly) = the distance light travels in one year = 1.0 x 1013 km. The elements that make up the star. How HOT is it?? The actual brightness of the star or its appearance of brightness.

  46. BRIGHTNESS OF STARS • Magnitude of stars • The amount of light a star gives off. (How BRIGHT it is) • Absolute Magnitude • The actual brightness of a star if a standard distance from Earth. • Apparent Magnitude • The brightness of a star as seen from the Earth. • Factors: • Distance • Size • Absolute magnitude

  47. BRIGHTNESS OF STARS INVERSE SQUARE LAW of LIGHT As light travels farther, it becomes more spread out, so there is LESS light per UNIT 2 . Farther away = Less light reaching Earth

  48. BRIGHTNESS OF STARS • The Magnitude Scale: • Ancient Greek put stars in 6 groups. • 1st group = brightest • 6th group = dimmest • The magnitude scale is based on that system. • Magnitude 1 = brightest • Magnitude 6 = dimmer

  49. BRIGHTNESS OF STARS • More numbers had to be added for brighter things. • What did they do? • Go NEGATIVE • Examples of Apparent magnitudes: • Sun -26.8 • Full moon -12.6 • Sirius -1.4 • The SMALLER or MORE NEGATIVE the number = BRIGHTER • https://www.youtube.com/watch?v=9P8Veb_AlJ0

  50. DISTANCE • Determining Distance of Stars • Method: PARALLAX – the apparent shift of an object when viewed from two different locations. • You can determine distance by measuring the angle of an object from the ends of the baseline of a triangle.

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