IB Astrophysics - intro to the universe - Flippingphysics by nothingnerdy
- 1. presents a production INTRODUCTION TO THE UNIVERSE based on the IB Astrophysics option 1
- 2. INTRODUCTION TO THE UNIVERSE What is there in the Universe? Asteroids and comets Moons Planets Stars Nebulae Stellar clusters Galaxies Galactic clusters
- 3. The Solar System RELATIVE SIZES: if Sun = 100, Earth =1 ... ... and the distance between them is 10 000 They all orbit the Sun on elliptical paths
- 4. The Sun Mass: 1.99 x 1030 kg Radius:6.96 x 108 m Surface temperature: 5800 K
- 5. Planets Data (and Pluto) Planet Picture Distance to the Radius (km) Orbital Orbital Surface Density/ Satellite Sun (km) period period day temp g/cm3 s around its (ºC) water=1 Mercury 58 million 4 878 km axis 59 days 88 days 167 5,43 0 Venus 108 million 12 104 km -243 days 225 days 464 5,24 0 Earth 149,6 million 12 756 km 23, 93 h 365,2 15 5,52 1 days Mars 228 million 6 794 km 24h 37min 687 days -65 3,04 2 Jupiter 778 million 142 800 km 9h 50min 12 years -110 1,32 +63 30s Saturn 1 427 million 120 000 km 10h 14min 29,5 years -140 0,69 +56 Uranus 2 870 million 51 800 km 16h 18min 84 years -195 1,27 27 Neptune 4 497 million 49 500 km 15h 48min 164 years -200 1,77 13 Pluto 5 900 million 2 400 km 6 days 248 years -225 2 1
- 6. Mercury and Venus The rocky planets closest to the Sun
- 7. Earth and Moon Mariner 10 Many planets have moons which orbit the planet (which orbits the Sun)
- 8. Mars The fourth of the inner planets Spirit Rover: Mars’ West Valley
- 9. Asteroid Belt Ceres (480km): it was the first asteroid to be seen. Now it’s a dwarf planet. Mathilde (52km) Eros (13x13x33km)
- 10. Jupiter The largest gas giant, 5 times more distant from the Sun than the Earth Jupiter and its moons: Io, Approximate size comparison Europa, Ganymede and Callisto of Earth and Jupiter
- 11. Saturn Nearly twice as far from the Sun as Jupiter A rough comparison of the sizes of Saturn and Earth
- 12. Uranus Twice as far from the Sun as Saturn Size comparison of Earth and Uranus
- 13. Neptune Nearly twice as far from the Sun as Uranus (30 times further than Earth) Size comparison of Neptune and Earth.
- 14. Astronomical units of distance The Astronomical Unit (AU) – this is the average distance between the Earth and the Sun. 1 AU = 150 000 000 km = 1.5x1011m
- 15. Astronomical distances The light year (ly) – this is the distance travelled by light in one year. c = 3x108 m/s t = 1 year = 365.25 x 24 x 60 x 60= 3.16 x 107 s Speed =Distance / Time Distance = Speed x Time = 3x108 x 3.16 x 107 = 9.46 x 1015 m 1 ly = 9.46x1015 m
- 16. Relative distances The Moon is 1.3 light seconds from the Earth The Earth is 500 light seconds from the Sun The nearest star to the Sun is about 4 light years away The diameter of a galaxy is about 100 000 light years The distance between galaxies is about 1 000 000 light years
- 17. Galaxies A galaxy is a collection of a very large number of stars (around 100 thousand million) mutually attracting each other through the gravitational force and staying together. The number of stars varies between a few million and hundreds of billions. There are approximately 100 thousand million galaxies in the observable universe. There are three types of galaxies: - Spiral (Milky Way) - Elliptical (M49) - Irregular (Magellanic Clouds)
- 18. Spiral Galaxies Spiral galaxies consist of a rotating disk of stars along with a central bulge of generally older stars. Extending outward from the bulge are relatively bright arms. There is a supermassive black hole at the centre. The dark patches in the picture is interstellar dust. Milky Way
- 19. Spiral Galaxies Andromeda galaxy is the closest large galaxy to Earth. It covers about the same area of the night sky as the Moon but is much dimmer.
- 20. Spiral Galaxies Sombrero Galaxy
- 21. Elliptical Galaxies M49 ESO 325-G004 Elliptical cross-section and no spiral arms. They range in shape from nearly spherical to highly flattened ellipsoids and in size from hundreds of millions to over one trillion stars. In the outer regions, many stars are grouped into globular clusters.
- 22. Irregular Galaxies Irregular galaxies have no specific structure. The Large and Small Magellanic Clouds, the nearest galaxies, are an example of irregular galaxies. Small Magellanic Cloud Hoag's Object, a ring galaxy.
- 23. Stellar cluster A group of stars within a galaxy which are close to each other, probably held together by gravitational attraction. They are all in the same direction from Earth and the same distance away. A stellar cluster can contain from hundreds to millions of stars. Messier 69 a globular cluster, part of the Milky Way is 30 000 ly distant and 42 ly across.
- 24. Constellations A group of stars in a recognizable pattern that appear to be near each other in space. They are in the same direction from Earth but are not necessarily the same distance away. Orion includes Bellatrix (250 ly); Betelgeuse (640 ly); Rigel (860 ly)
- 26. How the stars seem to move The night sky seems to rotate around a point above the Earth’s axis of rotation. In 24 hours, it completes a full circle. Over the course of a year, the stars are in a slightly different position each night due to the Earth’s tilt. Stars which are closer to the Earth also move relative to the background of more distant stars due to the Earth’s orbit around the Sun.
- 27. Nebulae Nebulous means ‘cloud-like’ Originally, ‘nebula’ was a general name for any extended astronomical object (the Andromeda Galaxy was referred to as the Andromeda Nebula before galaxies were discovered by Edwin Hubble). Nowadays, several different astronomical objects are known as ‘nebulae’. A nebula can be an interstellar cloud of dust, hydrogen gas and plasma. These nebulae are often star-forming regions, such as the Eagle nebula. A nebula can also refer to the remains of a dying star, a planetary nebula (eg Cat’s Eye nebula). Or it can be a supernova remnant (eg Crab nebula).
- 28. Nebulae Eagle Nebula and the Cone nebula: star-forming regions
- 29. Supernova remnants Crab Nebula - supernova remnant Eta Carinae - supernova remnant
- 30. Cat’s Eye Nebula Planetary nebulae are nebulae that form from the gaseous shells that are ejected from low-mass giant stars when they transform into white dwarfs.
- 31. Eskimo nebula Planetary nebula 3000 ly from Earth, discovered by William Herschel in 1787
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