Astronomy

1. Astronomy Nebular Theory, Stellar Evolution and the Big Bang Theory

2. 23.1- The Solar System • The Planets: An Overview • The 8 planets in our solar system can be separated into two different categories • Terrestrial planets • Jovian planets

3. 23.1- The Solar System • Terrestrial planets (inner planets) • Includes Mercury, Venus, Earth, Mars • Relatively small and rocky • What does terrestrial translate to? • “Earth-like” • Jovian planets (outer planets) • Includes Jupiter, Saturn, Uranus, Neptune • Huge gas giants • What does jovian translate to? • “Jupiter-like”

4. 23.1- The Solar System

5. 23.1- The Solar System • The Planets: An overview • Size is the most obvious difference between the terrestrial and Jovian planets • The Jovian planets are giants compared to the terrestrial planets • Density, what the planet is made of, and the rate of rotation are other ways in which the two groups of planets differ • Jovian planets are less dense while terrestrial planets are more dense • Jovian planets are made of gas • Jovian planets rotate around the sun much slower than the terrestrial planets

6. 23.1- The Solar System

7. 23.1- The Solar System • The Planets: An Overview • The Interiors of the Planets • All planets (and Pluto) are made up of gases, rocks, and ice • The Atmospheres of the Planets • Jovian planets have thick atmospheres of hydrogen, helium, methane and ammonia • Due to the large amount of gravity on these planets • Terrestrial planets have thin atmospheres • Due to the small amount of gravity on these planets

8. 23.1- The Solar System • Formation of the Solar System • Nebular Theory • A nebula is a cloud of gas and dust in space • According to the nebular theory, the sun and planets formed from a rotating disk of dust and gases. • As the disk rotated faster the sun formed in the middle

9. 23.1- The Solar System • Formation of the Solar System • Nebular Theory • Planetesimals • Planets grew as solid bits of matter began to collide and clump together through a process known as accretion. • The colliding matter formed small irregularly shaped bodies called planetesimals • As the collisions continued these planetesimals grew into planets https://www.youtube.com/watch?v=PL3YNQK960Y

10. 23.2- The Terrestrial Planets • Mercury: The Innermost Planet • The innermost and smallest planet in our solar system; just slightly larger than Earth’s moon • Surface Features • Has craters, similar to our moon. • Surface Temperatures • Has the greatest temperature extremes of any of the planets • It can get as cold as -173°C at night and as hot as 427°C during the day

11. 23.2- The Terrestrial Planets Mercury’s Surface

12. 23.2- The Terrestrial Planets • Venus: The Veiled Planet • Called “Earth’s twin” • Venus is similar to Earth in size, density, mass, and location in the solar system. • Surface Features • Covered in thick clouds that prevent light from hitting the planet • About 80% of Venus’s surface is covered in volcanoes • Surface Temperatures • Atmosphere is 97% carbon dioxide, making it VERY HOT!

13. 23.2- The Terrestrial Planets Venus’s Surface

14. 23.2- The Terrestrial Planets • Mars: The Red Planet • The Martian Atmosphere • Contains carbon dioxide with a small amount of water vapor • Extensive dust storms on Mars cause it to look different colors at times through a telescope from Earth • Surface Features • Consists of canyons, inactive volcanoes, and craters • These features are billions of years old

15. 23.2- The Terrestrial Planets

16. 23.2- The Terrestrial Planets • Mars: The Red Planet • Water on Mars • Some areas of Mars exhibit drainage patterns similar to those created by streams on Earth • Images from the Mars Global Surveyor indicate that groundwater has recently migrated to the surface http://www.cnn.com/2014/02/10/tech/innovation/mars-water-flows/

17. 23.3- The Jovian Planets (and Pluto) • Jupiter: Giant Among Planets • Jupiter has a mass that is 2.5 times greater than the mass of all the other planets and moons in our solar system combined. • Structure of Jupiter • Contains several gases such as hydrogen, helium, methane, ammonia, and water • Incredibly windy and cloudy • The “Great Red Spot” is a large storm, similar to that of a hurricane

18. 23.3- The Outer Planets (and Pluto)

19. 23.3- The Outer Planets (and Pluto) • Jupiter: Giant Among Planets • Jupiter’s Moons • Jupiter has 63 moons, which makes it resemble a mini solar system • Jupiter’s Rings • One of the most unexpected discoveries made by Voyager 1 • Thought to be formed of fragments from the collision of meteorites hitting two of Jupiter’s moons.

20. 23.3- The Outer Planets (and Pluto) • Saturn: The Elegant Planet • The most prominent feature of Saturn is its rings

21. 23.3- The Outer Planets (and Pluto) • Saturn: The Elegant Planet • Features of Saturn • Saturn’s atmosphere is very active, with winds roaring up to 1500 km/hr • Large storms similar to Jupiter’s “Great Red Spot” • Saturn’s Rings • Was once that that this was the only planet to have rings • The inner rings are more densely packed with particles while the outer rings are less densely packed with particles • Saturn’s Moons • Contains 31 moons • The largest moon is Titan, which is larger than Mercury

22. 23.3- The Outer Planets (and Pluto) • Uranus: The Sideways Planet • Uranus is unique in that it rotates on it’s side

23. 23.3- The Outer Planets (and Pluto) • Neptune: The Windy Planet • Winds exceeding 1000 km/hr make it one of the windiest places in the solar system

24. 23.3- The Outer Planets (and Pluto) • Pluto: Dwarf Planet • Until 2006 Pluto was considered to be a planet • Pluto is not considered to be a planet because its gravity is too weak to attract all nearby debris • As a result, the term Dwarf Planet was created. • Dwarf Planet: a round object that orbits the sun but doesn’t have a gravitational field strong enough to pull in all nearby debris

25. 23.3- The Outer Planets (and Pluto) • Pluto: Dwarf Planet

26. 23.4- Minor Members of the Solar System • Asteroids • Definition: small rock bodies that orbit the sun • Most asteroids lie in the asteroid belt between Mars and Jupiter. • Asteroids also have irregular orbits

27. 23.4- Minor Members of the Solar System • Comets • Definition: Pieces of rocky and metallic materials held together by frozen water and gases • Comets also orbit the sun

28. 23.4- Minor Members of the Solar System • Meteoroids • Meteoroid: a small, solid particle that travels through space • Meteor: the phenomenon observed when a meteroid enters Earth’s atmosphere and burns up, popularly called a shooting star • Meteorite: any portion of a meteoroid that reaches Earth’s surface

30. 23.4- Minor Members of the Solar System • Meteoroids • Meteoroids originate in one of the following ways • Debris that was not swept up by the gravity of other planets during the formation of the solar system • Material from the asteroid belt • Solid remains of comets that once traveled near Earth’s orbit

31. 24.1-The Study of Light • How do scientists know all this information about the planets? And how do they know so much about objects that are further away, such as stars? • The majority of the information we know about the universe is obtained from the study of light emitted from stars and other bodies in space.

32. 24.1-The Study of Light • Electromagnetic Radiation • Stars give off electromagnetic radiation (waves) • These electromagnetic waves have different wavelengths

33. Electromagnetic Spectrum

34. 24.1- The Study of Light • Electromagnetic Spectrum • The human eye can only see a certain range of wavelengths, in what is called the continuous spectrum • The continuous spectrum is caused by things like the sun or light bulbs

35. 24.1- The Study of Light • Electromagnetic Radiation • Emission spectrum • Also known as “bright line spectra” • These lines are made by glowing elements in a star, and can be seen with an instrument called a spectroscope • Below is the emission spectra of hydrogen produced by a star

36. 24.1- The Study of Light • Electromagnetic Radiation • Absorption Spectrum • When a visible spectrum of a star passes through the cooler outer atmosphere of the star

37. 24.1- The Study of Light • Electromagnetic Radiation • Absorption Spectrum • The gas in a star absorbs certain wavelengths of light, resulting in the appearance of dark lines • Most common spectra of stars • Also known as “dark line spectra” • Each spectrum is like a fingerprint of a star, telling us what element the star is made up of

38. 24.1- The Study of Light • The Doppler Effect • Moving sound sources produce perceived changes in pitch compared to the location of the observer https://www.youtube.com/watch?v=h4OnBYrbCjY • In astronomy, the doppler effect is used to determine whether a star or other body in space is moving away from or toward Earth

39. 24.1- The Study of Light • The Doppler Effect • Red Shift • Objects moving away from the observer exhibit a longer wavelength, or a shift towards the red end of the electromagnetic spectrum • Using the doppler effect, scientists have discovered that all stars and galaxies in the universe are red shifted. What does this mean? • All stars and galaxies in the universe are moving away from each other and the universe is expanding

40. 24.2- Tools for Studying Space • Telescopes • Instrument that aids in the observation of distant objects, such as stars and planets, that give off electromagnetic radiation • Types of Telescopes • Refracting Telescopes • Reflecting Telescopes • Radio Telescopes • Space Telescopes

41. 24.3- Tools for Studying Space • Types of Telescopes • Refracting Telescopes • Telescope that uses a lens to bend, or refract, light. • The objective lens bends all of the light rays onto one spot, the focus, or central point, so that the eye can see the object clearly

42. 24.3- Tools for Studying Space • Types of Telescopes • Reflecting Telescopes • A telescope that reflects light off of a mirror before it focuses the image • Benefits of the reflecting telescope • Lighter than the refracting telescope • Produces a clearer image

43. 24.3- Tools for Studying Space • Properties of Reflecting and Refracting Telescopes • Both reflecting and refracting telescopes have 3 properties that aid astronomers in their work • Light-gathering power (can see dim objects) • Resolving power (can see images clearly) • Magnifying power (can see small objects)

44. 24.3- Tools for Studying Space • Types of Telescopes • Radio Telescopes • Detect radio waves emitted by far away stars in space • A satellite TV setup is really just a simple radio telescope

45. 24.3- Tools for Studying Space • Advantages of Radio Telescopes • Less affected by the weather • Cheaper to build • Can be used during the day • Can “see” through interstellar dust and clouds

46. 24.3- Tools for Studying Space • Types of Telescopes • Space Telescopes • Orbit above Earth’s atmosphere • Advantages: • Above clouds and the Earth’s atmosphere • Can be used during the day • Disadvantage: • Expensive; if it breaks there is no way to fix it

47. 24.3- Tools for Studying Space • Types of Telescopes • Space Telescopes • Hubble Space Telescope • Launched in 1990 by the space shuttle “Discovery” • Photos are much higher in quality than Earth based reflecting or refracting telescopes

48. 25.1- Properties of Stars • Characteristics of Stars • Star Color and Temperature • Color is a clue to a star’s temperature • Red is cool • Blue is hot

49. 25.1-Properties of Stars • Characteristics of Stars • Binary Stars and Stellar Mass • Binary stars are two stars that revolve, or rotate, around each other • They rotate around each other at their center of mass. • Because of this, binary stars are used to find the mass of stars

50. 25.1-Properties of Stars • Measuring Distances to Stars • Parallax • Slight shift in the apparent position of a star in the sky • The closer the star, the more it appears to move in the night sky • The further away the star, the less it appears to move in the night sky