Origin of the Universe, Solar System and our Planet

1. Origin of the Universe, Solar System and our Planet

2. What do you know about the formation of the Universe? • When and how did Earth and its moon come into being? • How did the core, mantle, crust form?

3. A Quick Overview today’s Lecture • The Big Bang • Red Shift • Accretion of Solar System • Earth • Moon

4. Origin of the Universe • Provide important information concerning age of Earth • Fragments of larger bodies that have undergone collision and broken into pieces

5. Origin of the Universe • Stony meteorites • Rocky composition • Iron meteorites • Metallic composition • Stony-iron meteorites • Mixture of rocky and metallic • Proxy for core composition • Most date around 4.6 billion years ago

6. Origin of the Universe • Stars cluster in galaxies • Organized in disks • Milky Way • Our galaxy of stars M100 and NGC1365 are spiral nebulae

7. Question 1 Evidence for the Big Bang Hypothesis includes: A. Meteorites be dated at 4.6 Ga B. A shift towards the Red end of the visible light spectrum in different galaxies C. The Sun is made of 70% Hydrogen and 27% He

8. The Red Shift The Red Shift is similar to the Doppler effect with sound. For objects approaching us, the pitch of the sound is skewed to the higher frequency. Think of a train approaching and blowing its horn. Same thing for light waves.

9. 1912 Slipher - redshifts of spiral nebulae • Slipher measured spectra from the nebulae, showing that many were Doppler-shifted, that is, the frequency of light was affected by speed of the source (just as the frequency of sound alters for a passing train). By 1924, 41 nebulae were measured, and 36 of these were found to be receding.

10. Doppler • Stars and galaxies emit visible light which can be split up into its component colors to form a spectrum. Lines appear in this spectrum corresponding to the existence of different elements in the source of the light. If the source were stationary then the lines are in a particular pattern, which corresponds to the pattern produced by the same elements as are emitting light, on the surface of the Earth.

11. Doppler • If the source of light is moving towards the Earth then the wavelength of all the emitted waves is compressed a little. This results in a shift of the spectral lines into the blue part of the spectrum, known as a blue shift (middle panel). Conversely if the source of the light is moving away from the Earth then there is a shift of the lines into the red part of the spectrum known as a red shift, due to the wavelength of the emitted light all being extended a little (Bottom panel).

12. Red Shift vs Distance • If the red of light emitted from stars is plotted vs their distance from Earth, we see a relationship that indicates that the velocity an object is moving away from Earth is related to its distance

13. Origin of the Universe • Expanding universe • Galaxies move apart • Redshift • Originally concentrated into a single point • Big Bang • 15 billion years ago • Age of universe

14. The Big Bang (10-35 seconds) The universe begins with a cataclysm that generates space and time, as well as all the matter and energy the universe will ever hold. For an incomprehensibly small fraction of a second, the universe is an infinitely dense, hot fireball. The prevailing theory describes a peculiar form of energy that can suddenly push out the fabric of space.

15. The Universe Takes Shape (10-6 seconds)After inflation, one millionth of a second after the Big Bang, the universe continues to expand but not nearly so quickly. As it expands, it becomes less dense and cools. The most basic forces in nature become distinct: first gravity, then the strong force, which holds nuclei of atoms together, followed by the weak and electromagnetic forces. By the first second, the universe is made up of fundamental particles and energy: quarks, electrons, photons, neutrinos and less familiar types.These particles smash together to form protons and neutrons.

16. Formation of Basic Elements (3 seconds)Protons and neutrons come together to form the nuclei of simple elements: hydrogen, helium and lithium. It will take another 300,000 years for electrons to be captured into orbits around these nuclei to form stable atoms.

17. The Radiation Era (10,000 years)The first major era in the history of the universe is one in which most of the energy is in the form of radiation -- different wavelengths of light, X rays, radio waves and ultraviolet rays. This energy is the remnant of the primordial fireball, and as the universe expands, the waves of radiation are stretched and diluted until today, they take up the faint glow of microwaves which bathe the entire universe.

18. Beginning the Era of Matter Domination (300,000 years)At this moment, the energy in matter and the energy in radiation are equal. But as the relentless expansion continues, the waves of light are stretched to lower and lower energy, while the matter travels onward largely unaffected. At about this time, neutral atoms are formed as electrons link up with hydrogen and helium nuclei.

19. Birth of Stars and Galaxies (300 million years) Gravity amplifies slight irregularities in the density of the primordial gas. Even as the universe continues to expand rapidly, pockets of gas become more and more dense. Stars ignite within these pockets, and groups of stars become the earliest galaxies. This point is still perhaps 12 to 15 billion years before the present.

20. Birth of Stars and Galaxies (300 million years) The Hubble Space Telescope recently captured some of the earliest galaxies ever viewed. They appear as tiny blue dots in the Hubble Deep Field.

21. Birth of the Sun (5 Billion Years BP)The sun forms within a cloud of gas in a spiral arm of the Milky Way Galaxy. A vast disk of gas and debris that swirls around this new star gives birth to planets, moons, and asteroids. Earth is the third planet out.

22. Birth of the Sun (5 Billion Years BP)The image on the below, from the Hubble Space Telescope, shows a newborn star in the Orion Nebula surrounded by a disk of dust and gas that may one day collapse into planets, moons and asteroids.

23. A Hubble Space Telescope view of a small portion of the Orion Nebula reveals five young stars. Four of the stars are surrounded by gas and dust trapped as the stars formed, but were left in orbit about the star. These are possibly protoplanetary disks that might evolve on to agglomerate planets.

24. Origin of the Universe • The Earth is part of the Solar System; the Solar System is part of the Milky Way galaxy; and the Milky Way galaxy is part of the Universe. • The story of the origin and history of the Earth requires that the origin and history of the Universe and Solar System must be considered.

25. Origin of the Universe Evidence to be considered when interpreting the history of the Universe: • Galaxies are rapidly moving apart (Hubble's Law). Suggests that galaxies were closer together in the past. Discovered by Edwin P. Hubble in 1929. • Observed temperature of the Universe today (background microwave radiation) 3 degrees above absolute zero. • Present abundances of hydrogen and helium.

26. Origin of the Universe Interpretation: • The Universe is expanding. • Everything began together at a point. • A big explosion occurred, which astronomers call the Big Bang. • This explosion caused everything in the Universe to begin moving rapidly apart.

27. How do we know the galaxies are moving apart? • Red shift.In 1914, W.M. Slipher first noted that galaxies displayed the red shift.Their light is shifted toward the red (or long wavelength) end of the spectrum. • Colors of the spectrum ROYGBIV

28. What the Spectrum Reveals The spectrum of a star reveals: • The star's composition by means of absorption lines. Various elements in the star's atmosphere absorb parts of the light of the spectrum. • Whether it is moving toward or away from the Earth (and at what speed).

29. How do we know the galaxies are moving apart? • Light reaching us from distant receding galaxies has its absorption lines shifted toward the red end of the spectrum. This indicates that the galaxy is moving away from the Earth. • The red shift indicates that the universe is expanding.

30. Schematic view of the solar system, showing orbits of the planets.

31. Example of two fusion reactions. (n = neutron).

32. Origin of the Universe • Galactic matter is concentrated • Stars form • Our Sun • Supernova • Exploding star • Solar nebula • Dense rotational cloud

33. Origin of the Universe • Galactic matter is concentrated • Stars form • Our Sun • Supernova • Exploding star • Solar nebula • Dense rotational cloud

34. Origin of the Solar System • Rocky debris • Collided to form aggregates • Aggregates collided to form asteroids • 40 km diameter • Some coalesced to form planets

35. Conceptual diagrams of stages in the Earth’s early history. (A) Growth of the planet by the aggregation of particles and meteorites that accreted and bombarded its surface. At this time, the Earth was composed of a homogeneous mixture of materials. (B) The Earth has shrunk because of gravitational compression. Temperatures in the interior have reached a level at which differentiation has begun. Iron (red drops) sinks toward the interior to form the core, whereas lighter silicates move upward. (C) The result of the differentiation of the planet is evident by the formation of core, mantle, and crust.

38. Origin of the Solar System • Planets formed near time of sun’s formation • 4.6 billion years ago • Planets far from sun are formed from volatile elements • Planets close to sun are rocky

39. Sun's energy is the force behind many geologic processes on Earth • Evaporation of water to produce clouds, which cause precipitation, which causes erosion. • Uneven heating of the Earth's atmosphere causes winds and ocean currents. • Variations in heat from Sun may trigger continental glaciations or change forests to deserts. • Sun and moon influence tides which affect the shoreline.

40. The Planets • Mercury • Venus • Earth • Mars • Jupiter • Saturn • Uranus • Neptune • Pluto

42. Terrestrial planets: Small Dense (4 - 5.5 g/cm3) Rocky + Metals Mercury, Venus, Earth, Mars Jovian planets: Large Low density (0.7 - 1.5 g/cm3) Gaseous Jupiter, Saturn, Uranus, Neptune The Planets • Other: • Small • Low density • Pluto

43. Accretion and Differentiation of the Earth

44. Earth’s Internal Layered Structure • The Earth is internally layered, with a basic structure consisting of: • Crust • Mantle • Inner and outer core • The Earth's internal structure may be primary (formed initially as the Earth formed), or secondary due to later heating.

45. Solar Nebula Hypothesis or Cold Accretion Model(Secondary Differentiation) • Earth formed by accretion of dust and larger particles of metals and silicates. • Earth was originally homogeneous throughout - a random mixture of space debris. • Origin of layering requires a process of differentiation. • Differentiation is the result of heatingand at least partial melting.

46. Possible sources of heat for melting: • Accretionary heat frombombardment (meteorite impacts) • Heat from gravitational compression as material accumulated • Radioactive decay

48. Differentiation after Accretion • Iron and nickel sink to form core. • Less dense material (silicon and oxygen combined with remaining iron and other metals) forms mantle and lighter crust (dominated by silicon and oxygen). • Presence of volatile gases on Earth indicates that complete melting did not occur. • Earth was repeatedly partly melted by great impacts, such as the Moon-forming impact.

49. An alternative model:Hot Accretion (Primary Differentiation) • Internal zonation of planets is a result of hot heterogeneous accretion. • Hot solar nebula (over 1000 oC). • Initial crystallization of iron-rich materials forms planet’s core. • With continued cooling, lower density silicate materials crystallized.

50. Origin of the Solar System • Cold accretion model - Earth was initially unsorted material; but now layered. Requires a process of differentiation . Heating and at least partial melting. Iron and nickel sink to form core. Less dense material forms mantle and lighter crust. Source(s) of heat for melting? Accretionary heat from bombardment Heat from gravitational compression Radioactive decay