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Stars, RED SHIFT AND The Big Bang

Stars, RED SHIFT AND The Big Bang. S1-4-07a Investigate how scientists examine light from stars and describe the types of information revealed. S1-4-07b Compare and contrast scientific and cultural perspectives on the origin and evolution of the universe.

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Stars, RED SHIFT AND The Big Bang

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  1. Stars, RED SHIFT AND The Big Bang

  2. S1-4-07a Investigate how scientists examine light from stars and describe the types of information revealed. S1-4-07b Compare and contrast scientific and cultural perspectives on the origin and evolution of the universe. KEY WORDS Luminosity Apparent magnitude Absolute magnitude Electromagnetic spectrum Spectroscope Doppler Effect Red Shift Singularity Big Bang Astronomy Cosmology

  3. Stars - classified by luminosity, temperature and mass. Luminosity (brightness) There are two amounts (magnitudes) of brightness: • Apparent magnitude – brightness as we see it • Absolute magnitude – actually brightness The Sun has a higher apparent magnitude, since it is so much closer than other stars

  4. Star B looks brighter – more apparent magnitude Star B is closer to us than Star A Star B and A have the same absolute magnitude

  5. Temperature and Colour Colour – shows how much energy a star emits. • Colder star glows red • Hotter star glows bluish white or even blue Despite being cooler, the Sun is still bigger than about 95% of stars

  6. Notice bigger stars are not necessarily hotter…but usually brighter

  7. Analyzing Star light • Light is a type of energy called: Electromagnetic Energy • Scientists use a spectroscope to analyse the light energy coming from stars Spectroscope - splits light up into a pattern of colours, like a rainbow.

  8. Types of Electromagnetic energy Because of the shape of the waves, the colours always separate into the same organized pattern Low energy High energy ROYGBIV Red light is low energy – cool Blue is high energy - hot

  9. The Electromagnetic Spectrum • Visible section is the energy waves we can see • Energy waves we cannot see: ultraviolet, infrared, x-rays, microwaves, radiowaves, gamma rays • Heated compounds give off a uniquespectrum Scientists have heated elements and recorded the unique light energy patterns

  10. Each element in the star absorbs unique parts of the light energy as it is released. Showing as the “black” lines of missing energy The black lines in the spectrum are used to identify the elements that make up the star.

  11. The “missing” black lines in the spectra of the Sun match well with the emission spectra of Hydrogen but not with Mercury

  12. There is evidence that the universe is expanding: - Red-shift of light from stars and galaxies - Cosmic Microwave Background Radiation - Gravitational waves (new) Light waves work exactly like any other wave: Waves can be farapart - long wavelength Waves can be closetogether - short wavelength We’re going to focus on the oldest, and simplest – “red-shift” ROYGBIV

  13. Waves are also affected by motion. The noticeable effect is called the Doppler Effect. You have experienced this effect with sound waves Moving– compressedin front, spread out in back Stationary: all waves move outward evenly

  14. Doppler effect: Sound waves Higher pitch Lower pitch You brain hears the distorted wave pattern as a differentsound then is really being made by the ambulance

  15. Doppler effect: Light waves Blue shift Red shift You brain seesthe distorted wave pattern as a differentcolour then is really being made by the object

  16. a compressedgreenlight appears more blue “blue shift” • a s t r e t c h e dgreenlight appears morered “red shift” Your eyes don’t know what colour it “should” be, it can only interpret the waves it sees – it can’t tell the difference between “red” and “stretched green”

  17. Spectra of ALL stars and galaxies show red shift • Far away galaxies show more red shift - faster Evidence that the universe is expanding and speeding up too – think of it as the first half of an explosion Normal spectra “red shift” spectra “blue shift” spectra

  18. The universe is expanding: • Must have started out from one point – singularity Reverse the explosion – the Universe must have started from a packed, dense mass of material under pressure Big Bang • Rapid expansion of Universe from the singularity • Evidence suggests Universe is 14billion years old • Scientists cannot yetexplain all “how” or “why” • Not the only explanation of the universe origin BUT beliefs are not theories – only scientific theories can be tested and proven

  19. Astronomy – study of all objects in the universe. Cosmology – study of the origin of the universe.

  20. CAN YOU ANSWER THESE QUESTIONS? S1-4-07a: What information can scientists get by looking at light? How is a spectroscope used to identify star elements? S1-4-07b: How is the Doppler Effect used as evidence for the Big Bang? KEY WORDS Luminosity Apparent magnitude Absolute magnitude Electromagnetic spectrum Spectroscope Doppler Effect Red Shift Singularity Big Bang Astronomy Cosmology

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