1 / 57

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

miranda-lopez
Download Presentation

The Universe

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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.

More Related