Back of chapters have additional Resources and various tutorials to help you getting acquainted With the subject Also exercises you can do for extra

Transcription

1 Astronomy 100 Instructor: Prof. Irv Robbins Office:1N, room 233 Office Phone: Observatory Course requirements are at the Observatory Web site Via CSI web site then quick links to astrophysical observatory then by my NAME link, Also when logging into the Mastering Astronomy(MA) web site in the announcements There you will find tutorials, the course homework and chapter short exams First day notes you receive are a SUMMARY

2 Back of chapters have additional Resources and various tutorials to help you getting acquainted With the subject Also exercises you can do for extra credit->

3 KEEP IN MIND: THIS IS A WEB AUGMENTED COURSE ONLINE HOMEWORK 15% ONLINE EXAMS 20% =35% Mastering Astronomy website THESE ON LINE ASSIGNMENTS ARE AVAILABLE AS SOON AS A CHAPTER IS STARTED IN CLASS. YOU WILL SEE DUE DATES AND IN GENERAL HAVE 2 to 2 1/2 WEEKS BEFORE SIGNIFICANT LATE PENALITIES INCUR. Did the dude Say somtin? I think he means at 35% We better do it or Drop the class!

4 Observing Requirement -5% Report on 2 observations: use forms found on line or in back of the Lab manual CAN BE DONE AT ONE SESSION..ADDITIONAL ONES ARE EXTRA CREDIT. WHERE? CSI Observatory (open monthly see schedule on line Astrophysical Observatory website or local AAA observings Saturday nights in SI, Friday Night in Brooklyn or observatories in NJ These events are weather dependent so get it done early or a term paper as described at the web sites Is required. SEE LINKS AT MA AND OBSERVATORY WEB SITE

5 Extra Credit MAXIMUM of 5 points on final average ON UNDER THE GENERAL REQUIREMENTS LINK YOU WILL FIND ALSO ALL ASSIGNMENTS CONTAIN EXTRA CREDIT POSSIBILITIES. NOTE: IN CLASS MIDTERM and FINAL EXAMS 100 SHORT ANSWERS CRIB SHEETS (3) ALLOWED 2 PERIOD EXAMS=60% OF YOUR GRADE.

6 CHECK THESE LINKS OUT YOU WON T BE SORRY! HOW TO USE THE ONLINE CHAPTER REVIEWS AND TUTORIALS AND OTHER RESOURCES TO GET A GOOD GRADE HOW TO SUCCEED IN THIS ASTRONOMY COURSE

7 + ADDITIONAL VOLUNTEER EXTRA CREDIT ( depending on quality of work done). ATTENDANCE MONITOR, OBSERVING REPORT COLLECTOR AND GRADER Observatory Workers AUDIO MONITOR(sets up portable mic) Enter on the forms you receive in class, as well as, seating preference in room=your LEFT,RIGHT, Front, Back, Aisle seat (justify please). NORMALLY NO SPECICFIC SEAT WILL BE HONORED

8 Chapter 1 Our Place in the Universe

9 1.1 A Modern View of the Universe What is our place in the universe? Voids On the Large scale we first learned that Earth is a sphere some 2,500 years ago; we learned that Earth is a planet going around the Sun only about 400 years ago; and we learned that the Millky Way is only one of many galaxies with the work of Hubble some 80 years ago

10 Scale of the Universe Powers of Ten ---Eames film

11 Star A large, glowing ball of gas that generates heat and light through nuclear fusion

12 Planet Mars Neptune A moderately large object that orbits a star; it shines by reflected light. Planets may be rocky, icy, or gaseous in composition.

13 Moon (or satellite) An object that orbits a planet. Ganymede (orbits Jupiter) artificial objects (spacecraft) are usually called satellites and not moons

14 Asteroid A relatively small and rocky object that orbits a star. Ida (1) Note the non-spherical shape; small objects are often non-spherical because their gravity is not strong enough to compress the material into a sphere. (2) Asteroids are sometimes called minor planets because they orbit much like planets but are smaller than anything we consider to be a true planet.

15 Comet A relatively small and icy object that orbits a star. Halley s comet close-up. (1) the basic difference between an asteroid and a comet is composition; (2) (2) comets have tails ONLY when they come close to the Sun, not when they are much farther away.

16 A star and all the material that orbits it, including its planets and moons Solar (Star) System

17 Figure 1.9

18 Nebula Cloud like: Check out the Orion Nebula Birth place of stars An interstellar cloud of gas and/or dust Crab Nebula- Remnants of a Supernova Explosion But Andromeda Nebula is the nearest Spiral Galaxy to us (our Milky way)

19 Galaxy A great island of stars in space, all held 3 galaxies Large spiral Andromeda And 2 dwarfs elliptical together by gravity and orbiting a common center M31, The Great Galaxy in Andromeda common problems is confusion between the terms solar system and galaxy.

20 Universe The sum total of all matter and energy; that is, everything within and between all galaxies

21 How did we come to be? Hot & Dense Big Bang ->Expanding H&He->all other elements Galalxy recycles Birth Home, sweet home Life ->elements

22 Thus, we see objects as they were in the past: The farther away we look in distance, the further back we look in time. How can we know what the universe is like? We see by light (and other energies) Light travels at a finite speed (300,000 km/s). Or 186,000 mi/s circle earth about 8 times/sec Moon Sun Destination Light travel time 1 second 8 minutes Sirius 8 years Andromeda Galaxy 2.5 million years

23 Example: We see the Orion Nebula as it looked 1,500 years ago. M31, The Great Galaxy in Andromeda

24 Example: This photo shows the Andromeda Galaxy as it looked about 2 1/2 million years ago. Question: When will be able to see what it looks like now? photo also shows 100,000 years of time? M31, The Great Galaxy in Andromeda

25 Light-year The distance light can travel in one year. About 10 trillion km (6 trillion miles).

26 At great distances, we see objects as they were when the universe was much younger.

27 How far is a light-year? Distance=rate x time (60mi/hr x 3hr)=? Distance =km/s x s(in a year) 1light - year = (speed of light) (1 year) = 300,000 km s 365 days 24 hr 1 yr 1 day 60 min 1 hr 60 s 1 min Total number of seconds in a year Extra credit: Do this 1ly=?km Not accepted after a week!!!!

28 How far is a light-year? 1light - year = (speed of light) (1 year) = 300,000 km s = 9,460,000,000,000 km 365 days 24 hr 1 yr 1 day 60 min 1 hr 60 s 1 min Note: a light-year is a unit of distance NOT a unit of time.

29 Can we see the entire universe?

30 Thought Question Why can t we see a galaxy 15 billion light-years away? (Assume universe is 14 billion years old.) A. Because no galaxies exist at such a great distance. B. Galaxies may exist at that distance, but their light would be too faint for our telescopes to see. C. Because looking 15 billion light-years away means looking to a time before the universe existed.

31 Thought Question Why can t we see a galaxy 15 billion light-years away? (Assume universe is 14 billion years old.) A. Because no galaxies exist at such a great distance. B. Galaxies may exist at that distance, but their light would be too faint for our telescopes to see. C. Because looking 15 billion light-years away means looking to a time before the universe existed.

32 1.2 The Scale of the Universe How big is Earth compared to our solar system? Roughly 100 earth s span the sun s diameter! Let s reduce the size of the solar system by a factor of 10 billion; the Sun is now the size of a large grapefruit (14 cm diameter). How big is Earth on this scale? A. an atom B. a ball point C. a marble D. a golf ball

33 Let s reduce the size of the solar system by a factor of 10 billion; the Sun is now the size of a large grapefruit (14 cm diameter). How big is Earth on this scale? A. an atom B. a ball point C. a marble D. a golf ball 2 x too big For earth Here!

34 How big is the Universe? The Milky Way is one of about 100 billion galaxies stars/galaxy x galaxies = stars As many stars as grains of (dry) sand on all Earth s beaches

35 How do our lifetimes compare to the age of the Universe? The Cosmic Calendar: a scale on which we compress the history of the universe into 1 year.

36 How do our lifetimes compare to the age of the Universe? The Cosmic Calendar: a scale on which we compress the history of the universe into 1 year.

37 1.3 Spaceship Earth How is Earth moving in our solar system? Contrary to our perception, we are not sitting still. We are moving with the Earth in several ways, and at surprisingly fast speeds ~1000 mi/hr The Earth rotates around its axis once every day. That s a thousand miles/hr at the equator: most of us are moving in circles around the axis at speeds far faster than commercial jets travel, which is why jets cannot keep up with the Sun when going opposite Earth s rotation

38 Earth orbits the Sun (revolves) once every year: at an average distance of 1 AU 150 million km. with Earth s axis tilted by 23.5º (pointing to Polaris) and rotating in the same direction it orbits, counterclockwise as viewed from above the North Pole. ORBIT. surprisingly high speed of over 100,000 km/hr=62,000 mi/hr We better not hit something!

39 Our Sun moves randomly relative to the other stars in the local Solar neighborhood typical relative speeds of more than 70,000 km/hr but stars are so far away that we cannot easily notice their motion And orbits the galaxy every 230 million years.

40 More detailed study of the Milky Way s rotation reveals one of the greatest mysteries in astronomy: Most of Milky Way s light comes from disk and bulge. but most of the mass is in its halo Halo What mass? -> DARK MATTER?

41 How do galaxies move within the universe? Galaxies are carried along with the expansion of the Universe. But how did Hubble figure out that the universe is expanding?

42 Hubble discovered that: All galaxies outside our Local Group are moving away from us. The more distant the galaxy, the faster it is racing away. Conclusion: We live in an expanding universe.

43 Are we ever sitting still? Earth rotates on axis: > 1,000 km/hr Earth orbits Sun: > 100,000 km/hr Solar system moves among stars: ~ 70,000 km/hr Milky Way rotates: ~ 800,000 km/hr Milky Way moves in Local Group Heh Prof? How come I don t feel it? Universe expands

44 1.4 The Human Adventure of Astronomy How has the study of astronomy affected human history? Copernican Revolution showed that Earth was not the center of the universe (Chapter 3) Study of planetary motion led to Newton s Laws of motion and gravity (Chapter 4) Newton s laws laid the foundation of the industrial revolution Modern discoveries are continuing to expand our cosmic perspective Development of the scientific method has brought many Humans out of the age of superstition and enriched our lives With great material wealth (but not all earthlings participate at this time!)

45 Astronomy led to Physics (What is it?) Fundamental Science Concerned with the fundamental principles of the Universe Foundation of other physical sciences Has simplicity of fundamental concepts Divided into five major areas ALL AREAS ARE USED TO INTERPRATE OUR UNIVERSE Classical Mechanics Thermodynamics Electromagnetism Optics Relativity \ Modern Physics EINSTEIN STARTED Quantum Mechanics /

46

47 Our Earth is a dynamic Rocky Planet of constant Change in the family of the Sun (Solar System)

48 Nearest to us in our Solar System is The Moon-a large rocky body

49 Figure 1.8 Arizona?

50 The Sun Rules the Solar System

51 The Sun s energy is driven by Nuclear Fusion- made up of matter in the plasma state interacting with strong magnetic forces Haunting images from the Sun

52 Venus in the Pleades Cluster

53 Why is dark side lit? <-Jupiter & moons

54 Radar view of Venus breaks through the clouds to reveal a young volcanic world

55 Mars from the Hubble Space Telescope Clouds, deserts, craters and Ice cap are viewed

56 Size-wise Mars is humble yet has the greatest Volcanoes and canyons of the Solar System

57 Jupiter IO EUROPA GANYMEDE CALLISTO These are the size Of the planet Mercury

58 Saturn and its mysterious rings

59 Unnumbered Figure 1.1 PLUTO THE LITTLE PLANET THAT COUDN T

60 The Solar system also contains, Comets and Asteroids. Which can be lethal to life on planet Earth from time to time.

61 Asteroid Gaspra

62 Our Milky Way galaxy from Earth contains > 150 billion other Suns and their systems( NOTE: Dust, glowing gas and stars)

63 Our Milky Way Galaxy in Infared (IR) radiation Deep Sky: Spiral Galaxy M61 In VIRGO

64 Deep Sky: Lagoon Nebula= a Stellar nursery In the our Milky Way Galaxy New Stars are born from condensing gas and dust

65 Deep Sky: Horsehead Nebula Combination of Dust and Gas in Our Milky Way Galaxy..located in Orion s star birth area A Dark Nebula

66 Deep Sky: The Rosette Nebula -emission nebula-3000 light-years away in Our Galaxy. Stellar wind from the open cluster of stars, NGC 2244, has cleared a hole in the nebula's center. Green= oxygen Blue= sulfur Red=hydrogen NOTE: ELEPHANT S TRUNKS

67 Deep Sky (Hubble): Newborn stars and their Solar Systems are forming in theeagle Nebula. The giant pillars (elephant trunks) are light years in length and are so dense that interior gas contracts gravitationally to form stars. Stellar nurseries are exposed.. The Eagle Nebula, lies about 7000 light years away

68 Deep Sky:The Pleiades, the most famous open cluster on the sky. Also called the Seven Sisters, M45 or Subaru is very bright and easy to see even in NYC. The Pleiades contains over 3000 young stars, is about 400 light years away, and only 13 light years across. Note the blue reflection nebulae surrounding the bright stars.

69 Deep Sky: Over 200 globular star clusters orbit the center of our Milky Way Galaxy, 47 Tucanae is the second brightest, Known also as 47 Tuc or NGC 104, visible from the Southern Hemisphere. Light takes about 20,000 years to reach us. Red Giant stars (yellowish) are easy to see. Stars in the cluster are very ancient! with Simple Chemistry And ages 10 to12 Billion Years Old!

70 Deep Sky: The Planetary Nebula (show) Glowing gaseous shrouds shed by dying sun-like stars trying to stabilize as they run out of nuclear fuel.. Typically 1,000 times the size of our solar system These Ten have names like Owl, the Cat's Eye, the Ghost of Jupiter, Ring. This glorious final phase in the life of a star lasts only about 10,000 yrs. Note: The Star Remnant At center of The Planetary Nebulae. Called Planetary Because the Resemble planets In a telescope GOOD-BYE PLANETS!

71 Deep Sky: Supernova Remnant: The Crab Nebula, filled with mysterious filaments, is the result of a star that was seen to explode in 1054 AD. This spectacular supernova explosion was recorded by Chinese and Anasazi Indian astronomers. In the very center lies a pulsar: a neutron star rotating. 30 times a second.

72 Deep Sky: Andromeda Nebula = Andromeda Spiral Galaxy.. Note two dwarf elliptical galaxies

73 Very Deep Sky: The Virgo cluster of Galaxies. Our Galaxy is in this group.

74 A very distant cluster of mostly spiral galaxies, half-way across the universe

75 Hubble: Ultra Deep Field.. Oldest and most distant Galaxies ever Found. Formed 13 billion years ago. Hubble spent 3 month imaging the Same spot.

76 Some final perspective when life gets you down Tree of Life MONTY PYTHON UNIVERSE SONG Homer has the last word on the scale of the Universe