Review Astronomy 1 Elementary Astronomy LA Mission Col ege Spring F2015

Transcription

1 Review Astronomy 1 Elementary Astronomy LA Mission College Spring F2015

2 Quotes & Cartoon of the Day One may wonder, What came before? If space-time did not exist then, how could everything appear from nothing?... Explaining this initial singularity where and when it all began still remains the most intractable problem of modern cosmology. Andrei Linde But who shall dwell in these worlds if they be inhabited?... Are we or they Lords of the World?... And how are all things made for man? Johannes Kepler Our sun is one of 100 billion stars in our galaxy. Our galaxy is one of billions of galaxies populating the universe. It would be the height of presumption to think that we are the only living things in that enormous immensity. Wernher von Braun

3 Announcements Observing Project & Extra Credit Due Midterm graded & gradebook updated to drop lowest remainder of grading (hopefully) updated this weekend Final 12/15 at AM!

4 Last Class Debrief Midterm Debrief LT Cosmology & Fate of the Universe Exoplanets (time permitting)

5 This Class Review/Debrief Midterm Exoplanets (time permitting)

6 About the Final Astronomy 1 Elementary Astronomy LA Mission College Spring F2015

7 About the Final Similar format to Midterms Similar length a little longer, some choice of questions Little new material, mostly cumulative Study the stuff on the midterms! But don t memorize the questions themselves, you probably won t see many that are identical You may bring a full sheet of notes both sides handwritten

8 About the Final Don t leave stuff blank! Can you remember ANYTHING about the topic? Apply logic! Comprehension before Computation -- Big Picture before Details State units with numbers (except magnitude)

9 Topics Astronomy 1 Elementary Astronomy LA Mission College Spring F2015

10 TOUR OF UNIVERSE

11 Our Cosmic Address LAMC Sylmar Los Angeles County CA US Earth Solar System Milky Way Galaxy Local Group Virgo Supercluster The Universe

12 SCIENCE

13 Science Definition Method KEY: Hypothesis, Test, Revision Nomenclature -- Hypothesis, Theory Characteristics of Science & Belief System Be able to recognize science and not-science Be able to recognize a scientific hypothesis Be able to describe the scientific method

14 THE NIGHT SKY

15 Diurnal Motion Daily Everything Rises in East, sets in West Moves in circles around the NCP (and SCP) Earth is rotating Be able to answer questions using diagrams from the Position LT

16 Lunar Phases Cause of phases ID of phases Timing of rise/set/transit

17 Eclipses Solar and Lunar Cause Geometry Timing Why not every full/new moon

18 Zodiac & Apparent Solar Motion Ecliptic Zodiac Meaning of The Sun is in Taurus etc. Takes a year to cycle through

19 Seasons It s the axial tilt It s about energy transfer Be able to discuss observable consequences when is the Sun high in the sky, day length etc.

20 OLD DEAD GUYS

21 Greeks to Kepler Greek ideas Copernican Revolution Tycho Brahe Kepler the dude

22 Kepler s 3 laws of Planetary Motion 1. The orbits of the planets are ellipses, with the Sun at one focus. 2. A line from a planet to the Sun sweeps out equal areas in equal periods of time Planets move fastest when physically closest to the Sun, and slowest when farthest. 3. A planet s orbital period squared, is proportional to it s farthest distance from the Sun cubed: P 2 = a 3 Be able to recognize these Work with ellipses and eccentricity Recognize examples of 2nd and 3rd law (faster/slower longer period/ shorter period) Possible calculation with 3rd law

23 Kepler to Sir Issac Galileo Sir Issac Contributions and fields of study Law of Universal Gravity

24 Law of Universal Gravity Be able to explain how the force varies (larger or smaller) with mass of either object, both objects and distance Be able to work the inverse square relationship -- how does force change if distance doubles...

25 LIGHT, OPTICS, TELESCOPES

26 Nature of Light Why this is important for Astronomy electromagnetic radiation waves, particles, duality all light, from radio to gamma ray is same thing all light travels at the same speed in vacuum c=3x108 m/s

27 Properties of Light Waves Relationship of wavelength and frequency λ = c/f Interference Particles Photoelectric effect E = h f = hc/λ h = 6.6 x Js = 6.6 x J/Hz Know what these relationships mean Know how the ranking task worked Possibility of seeing a a simple calculation

28 Electromagnetic Spectrum difference between red and blue light Basic bands of EMR (e.g. radio, visible, IR etc.) Relationship between band, wavelength & Energy

29 Telescopes and Observatories Refractors and Reflectors Size (of primary) matters Atmospheric Transmission & Seeing Multiwavelength Astronomy What are IR and Radio good for? Cameras & Spectroscopes

30 SOLAR SYSTEM

31 Solar System Properties Overall bulk properties Disk shape two types of planets Space debris common age

32 Solar System Properties Anatomy What and Where Sun Inner SS & terrestrial planets Asteroid Belt Outer SS & Jovian planets Kuiper Belt Heliopause Oort cloud Size/Distance Scales

33 Solar System Formation Raw materials -- big bang, role of supernovae Theories of Formation Solar Nebula Theory Differentiation Frost line Planet formation -- both types Disk clearing Cratering & Craters

34 Solar System Bodies Terrestrial Planets common properties dynamo effect What went wrong for Venus and Mars Greenhouse effect Jovian Planets common properties Why are Titan and Enceladus interesting Why isn t Pluto a planet and what it is

35 STARS & GALAXIES

36 Stellar Properties Luminosity Magnitude system Apparent vs. Absolute magnitude review the ranking tasks Distance ladder & difficulty of distances Stellar parallax know how angle & distance relate Standard Candle how does a standard candle work

37 Color and Temperature & Size stars are (mostly) like blackbodies temperature and peak wavelength temperature and size & luminosity

38 Spectral Type Color ~ temperature ~ spectral class be able to answer questions based on the blackbody LT Harvard computers & Harvard classification scheme OBAFGKM Brightness and temperature and size (Giants)

39 HR Diagram What is it? What can be plotted on it? Main sequence Red giants Supergiants White Dwarfs Evolution

40 Stellar Lifecycles NASA Star formation Main Sequence lifetime End states and what determines them Mass is everything!!!!! More mass means shorter life

41 Main Sequence & Red Giant phase Main Sequence Hydrostatic Equilibrium H to He nuclear fusion Most of a star s life Sun is on MS Red Giant New hydrostatic equilibrium H to He fusion in shell He fusion in core 1/10th the duration of MS lifetime

42 Endgame Scenarios Giant stars Planetary nebulae White dwarfs Type II supernovae neutron stars & pulsars black holes type Ia supernovae

43 The Milky Way Barred Spiral General structure disk, bulge, halo General Content Where are we?

44 Galaxy Classification NASA/ESA

45 Characteristics of types Describe spirals, barred spirals, ellipticals, irregulars Which are most common? What are their overall properties? Which tend to have older or younger stars Which tend to have black holes (all)

46 COSMOLOGY

47 Telescopes are Time machines Lookback time Concept of the Observable Universe

48 Expanding Universe Space is expanding, not stuff Raisin bread & balloons Cosmological principle Role of gravity in holding structures together

49 Big Bang NOT an explosion Universe was infinite immediately How long ago was it? The whole universe was in a hot, dense state energy became matter became stars and galaxies Evidence for Big Bang Expansion H,He,Li abundance in early universe Cosmic Microwave Background

50 Cosmic Microwave Background Penzias & Wilson 2.7 K Very smooth but somewhat bumpy Not the very beginning, 380,000 years after BB

51 Fate of Universe 3 fates: Open, Closed, Critical or Big Crunch, Big Chill/ Big Rip Dark Matter & Dark Energy Most of universe is dark Dark Matter Dark energy dominates universe Dark energy is unknown cause of local expansion

52 EXOPLANETS

53 Exoplanets If we get to them today

54 IN SUMMARY

55 The Galaxy Song

56 So Long and Thanks for All the Fish!

57 Other Worlds Extrasolar planets and systems Astronomy 1 Elementary Astronomy LA Mission College Spring F2015

58 There are a lot of planets out there! extrasolar planets around 1225 stars multiple planet systems catalog/ Simple flat-table list 4696 Kepler candidates!

59 There are a lot of planets out there! 298 are very large Radius larger than 6x Earth 150 are small Radius less than 1.25 x Earth

60 DETECTION METHODS

61 Direct imaging Rare Radial Velocity (RV) How do we find them? Planet induces doppler shift in parent star Transit photometry Planet blocks light from parent star Gravitational microlensing Planet causes background object to brighten Astrometry Planet causes parent star to shift position periodically

62 Exoplanet Image Beta Pictoris about 63.5 light years from Earth Beta Pictoris b (bright spot) orbiting its star (center) Credit: Bruce Macintosh et al. Beta Pic b (planet) dist from Beta Pic about 9x dist Earth from Sun VERY large, ~ 1.6x radius of Jupiter

63 RV Animation

64 Transit Method Animation

65 KEPLER

66 Kepler Capable of finding earth-sized planets in the habitable zone of nearby stars Transit method 962 confirmed planets to date Now in modified extended mission K2 (has lost 2 reaction wheels)

67 Kepler Overview

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69 MOST EARTHLIKE PLANET EARTH 2.0 KEPLER 452B

70 Transit Graph

71 Artist s Concept

72 Kepler 452b

73 Kepler 186-f came first Kepler 186f discovered April 2014 was first Earth-size planet in Habitable zone. Composition not as clearly confirmed as rocky Orbits very close to a dim M-type Star about 500 ly distant

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75 Earth 2.0 Kepler 452b Discovered July 2015 (press con 7/23) Orbits G-type Star about 1400 ly distant