Topic 3 - Waves and the Universe

Topic 3 - Waves and the Universe

1. Our solar system is part of the milky way galaxy

   • A galaxy is a collection of stars
     • Universe includes all galaxies
   • Moon, Earth, Planets, The sun and other stars, Galaxies, Universe

2. Relative distances of planets

3. Modern Telescopes do not use only visible light waves. Stars and other objects also emit Electromagnetic Waves like infra-red, ultra-violet, Radio, Gamma and X-rays. Some do not emit visible light waves at all and therefore can not be seen by using naked eye or simple telescopes.

   • Improved magnification allows us to see galaxies, telescopes using other EM spectrum rays can detect objects not detectable using visible light, Can collect more data using digital cameras.
   • Telescopes often placed higher up as there is less atmosphere and so less light is absorbed by atmosphere, can see more clearly. Dust, water vapour and moving air can all distort visible light images.

4. Space Probes - Fly past planets or go into orbit around them. Take pictures of the surfaces of other planets and send the images back to earth.

   • Landers and Rovers - Land on planet and take close-up pictures as well as testing soil samples for microbes or substances indicating life.
     • Lander - Stays in one place. Rover - Can move around.

5. Spectrometer splits light into it's different colours.

   • Can be made with CD or DVD
   • Black lines in the spectrum show that some light is absorbed by atmosphere.

6. Life cycle of stars

   • Stars with similar or lower mass than the sun
     • Stage 1 - Nebula is a cloud of dust and gas. Gas is mostly hydrogen. Dust and gas pulled together by its own gravity, as more is pulled in the strength of gravity increases pulling more in. Hydrogen gets hotter as its gravitational potential energy is converted to kinetic energy, move faster, become hotter
       • Stage 2 - gas gets hot enough for the nuclei of the hydrogen atoms to begin to fuse together. Fusion reactions fuse hydrogen nuclei together into helium and produce a lot of energy, star starts to shine. this stage is called the main sequence. the sun is in it's main sequence.
         • Stage 3 - After around 10 billion years, the star has used up most of its hydrogen fuel and so starts to fuse helium nuclei. The star swells into a red giant.
           • Stage 4 - Eventually all elements taking part in fusion reactions are used up and fusion reactions in the star stop. Gravity pulls the material together to form a much smaller white dwarf star, the star gradually cools down.
   • Higher mass than our sun

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