Скачать презентацию Unit Earth in Space Topic 1 The Night

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Unit Earth in Space. Topic 1: The Night Sky. Vocabulary Terms to know for the Regents: Horizon, altitude, coordinate system, constellation, zenith, Polaris, ecliptic, lightyear 1

• A. Mapping the Sky • As with any mapping, it is essential to make a grid or coordinate system that uses an 'x' and 'y' axis to locate positions. • For space, astronomers use a few different terms for each axis. All the points are measured in units of space called degrees. Degrees are broken into 60 minutes which are each broken into 60 seconds • This has nothing to do with TIME!!! • 2

From anywhere on earth (and in Astronomy magazine), coordinate points have these names: Up From the celestial equator: (the extension of the earth's equator into space) The 'y' axis point is called declination Across From the point at which the sun crosses the celestial equator during the spring equinox: The 'x' axis point is called the right ascension or hour circle 3

Terms we use when viewing from home: Up Across From any point on your horizon, looking up into the sky: The 'y' axis point is called the altitude Starting with due North as 0º, East is 90º, South is 180º and West is 270º: back to north at 360 The 'x' axis point is called the azimuth 4

• Example: if you were looking at Scorpio and so was someone in Liberia, you would use the same declination and right ascension to describe the locations. (just like using Latin to name living things). These measurements would be the same no matter what day or time you looked at it!!!! 5

• However, if you wanted to tell me where Scorpio was, looking from your backyard, you would measure its height above the horizon (altitude) and use a compass to tell me how far from due North it was (azimuth). These are only good from your house at the exact hour and day you took the measurements!!! 6

• Things to See: • Using a star chart, find: • the ecliptic (line the sun seems to follow through the stars during the year) • the zenith (point directly over an observer) • Polaris (the North Star: notice it is always in the northern sky, at the exact same position, all the time!!) 7

• Find the Ursa Major constellation, which contains the Big Dipper • Learn to find Polaris by using the Big Dipper's 'pointer stars' • The sky is divided into 88 sections called constellations, and stars in these sections are used to make pictures in the sky. 8

• All of the stars you are looking at are many lightyears (the distance light travels in a year, which is trillions of miles) away. 9

B: The Origin of the Universe: • Vocabulary to know for the Regents: • Universe, stars, fusion, galaxies, Milky Way Galaxy, local cluster, cosmic background radiation, spectrum, spectroscope, electromagnetic radiation, red-shift, Doppler Effect 10

Astronomy Notes: Deep Space Hubble overview: http: //hubblesite. org/explore_astronomy and Journey to a Black Hole: http: //hubblesite. org/explore_astronomy/black_holes/ho me. html and then http: //amazingspace. stsci. edu/resources/explorations to do the following: planet impact, mission mastermind, Hubble Deep Field Academy, Telescopes from the Ground up, Galaxies from the Ground Up, and No Escape: The truth about black holes 11

Age: est. 13. 7 billion years old 12

I. The Big Bang 1. 13. 7 billion years ago, the Universe (all known matter and energy) began in a moment of time in which energy began to be changed into matter. (That's basically what E=mc 2 means). 13

• In the beginning was…. ? ? Sphere of energy? ? Time and space did not exist • the energy became unstable and exploded…. • energy cooled over the first million years, and subatomic matter formed 14

• Over time, electrons, protons and neutrons formed. As these slowed down a little, • atoms of Hydrogen began to form. In time, gases coalesced to form stars, which are spheres capable of fusion (making heavier atoms from lighter atoms at millions of degrees). 15

3. Galaxies 3. Many pockets of gas became galaxies of billions of stars moving together through space. Galaxies grouped together to form clusters of galaxies. • http: //www. universetoday. com/36302/atoms-in-the-universe/ image big bang 16

4. Our galaxy is the Milky Way Galaxy, a spiral galaxy 100, 000 ly across and 10, 000 ly high. 200 billion stars. A side view: • From http: //www. astrodigital. org/astronomy/milkywaygalaxy. html 17

And the overview: 18

• Ours is one of 22 galaxies in our local cluster. The nearest spiral galaxy to us is the Andromeda Galaxy. http: //metododeltocino. blogspot. com/2014/09/super-super-cumulo. html 19

II: Measuring Our Universe • 1. Ever since that first initial violent explosion, our universe has continued to expand. a. How do we know? We watch all types of stars, nebula, galaxies, quasars, pulsars, and black holes. https: //starchild. gsfc. nasa. gov/docs/Star. Child/universe_level 2/quasars. html b. Most importantly, astronomers discovered cosmic background radiation that seems to be great energy left over from a terrific explosion. http: //www. classzone. com/books/earth_science/terc/navigation/chapter 28. cfm http: //csep 10. phys. utk. edu/astr 162/lect/cosmology/cbr. html 20

• Evidence of an expanding universe: –Doppler Effect: most galaxies show red shift : –farthest galaxies show most shift • http: //www. classzone. com/books/earth_science/terc/navigation/chapter 28. cfm 21

2. Electromagnetic Energy (EME) • All matter gives off electromagnetic radiation (including you? ), which is measured in wavelengths and frequencies of both visible and invisible light. See page 14 of ESRTand lab 8 -7. 22

3. These wavelengths make up the spectrum. Each substance gives off its own spectra when viewed through a spectroscope. (We'll do this using charts and in lab). 23

Doppler Shift 4. When an object moves away at great speeds, its spectra shifts to longer wavelengths (red-shift) and • when it is moving towards us its spectra shifts to shorter wavelengths (blue-shift). • The faster it is moving, the greater the shift will be. This is called the Doppler Effect. 24

5. When we look at stars, we are looking backwards in time. The farthest quasars (very old stars) are 47 billion ly away. 6. Present predictions are for the universe to continue to move outward forever. Too bizarre! • • • http: //astro. unl. edu/classaction/animations/light/hydrogenatom. html http: //astro. unl. edu/classaction/animations/light/threeviewsspectra. html http: //astro. unl. edu/classaction/animations/light/radialvelocitydemo. html • http: //www. classzone. com/books/earth_science/terc/content/visualizations/es 2 802/es 2802 page 01. cfm? chapter_no=visualization 25

III: Stars • The matter in the universe separated in all directions. • Most matter is in the form of stars or star dust. (You and I are star dust!!) • 80 -90% of the mass of the universe is invisible dark matter and dark energy. None of our instruments can detect them, but we know they must be there due to the laws of gravity!! 26

Classification of stars • 2. On the H-R diagram, stars are classified according to their size, temperature and luminosity (how bright the star REALLY is). • H-R Diagram: Temperature vs. luminosity chart. • • Page 15 of ESRT: shows 4 main classes of stars. • http: //casswww. ucsd. edu/public/tutorial/HR. html • http: //www. astro. ubc. ca/~scharein/a 311/Sim/hr/HRdiagram. html • See page 15 of ESRT , text p. 626 and lab 8 -8 for classifications. 27

• 3. All stars begin as protostars when space dust has formed a sphere that becomes very hot, leading to fusion: when hydrogen is turned into helium in its core. 28

• 4. The Main Sequence Stars are stars that are stable and have a lot of hydrogen left in their cores. • These include: 29

Hubble video • https: //www. youtube. com/watch? v=5 c 3 xu. Ys 75 IU • https: //www. youtube. com/watch? v=TF 61 So 6 C 0 m 8 • https: //www. youtube. com/watch? v=o. AVj. F_7 ensg 30

a. Blue Supergiants: massive stars that only exist millions of years before they • Expand to become cooler Red Supergiants • That will blow up (supernova), creating nebula (large clouds of star dust) and either neutron stars or black holes. Large stars create helium, lithium…. . iron. 31

b. Stars like our star, the Sun, are typical main sequence stars. – It is not very large or hot. – When it becomes old (uses up its hydrogen) it will expand become a Red Giant. • • http: //sohowww. nascom. nasa. gov Age: 4. 6 billion years old Red Giant stage in 5 billion years. It will nova and become a white dwarf. 32

• Red Dwarf stars are very small and cold, and use up their fuel slowly. • they ‘live’ for many billions of years before becoming brown dwarf stars…. 33

3. After the Main Sequence • The Red Supergiants are the second stage in a blue supergiant’s ‘life cycle’. These supernova and leave black holes and neutron stars. • White and Brown Dwarf Stars are the remnants of exploded Red Giants. 34

• Heavy elements are formed during these massive explosions and interactions. • The matter in the universe is constantly recycled into new dust and stars and energy. Nothing has been added or taken away (according to the laws of Physics) since the initial Big Bang. 35

1. The Life Cycle of Stars: • Protostar (from nebula) • Main sequence (stable) • Uses up hydrogen, expands and cools • Either novas or supernovas • Becomes either white dwarf, neutron star or black hole, depending on how much mass it had. • http: //www. classzone. com/books/earth_science/terc/navigation/chapter 28. cfm 36

2. Classification of Stars: a. . Star Temperature and color: • Hot stars are blue, cool stars are red b. Star Luminosity (absolute magnitude): star’s TRUE brightness compared to the sun: big stars are bright, dwarf stars are dim. 37

3. Spectra of starlight • a. Composition of the star: what elements are in the star and in its atmosphere. • b. Spectra tells us that, because each element has its own spectral fingerprint. • http: //astro. unl. edu/classaction/animations/light/spectrum 010. html 38

C. Electromagnetic Spectrum: 1. energy given off in transverse waves. 2. All EME travels at the speed of light. Longer wavelengths = lower energy have low frequency • Shorter wavelengths = more energy • have higher frequency • • P. 14 ESRT 39

• D. Our star (sun) gives off primarily visible light has a continuous spectrum of VISIBLE LIGHT • Sun also gives off UV, infrared, and other wavelengths • 40

4. Measuring Distances and Energy in Space: • A. Lightyear is the distance light travels in a year. • Speed of light: 186, 000 miles/second – (670, 000 miles/hr) • Lightyear : 10 trillion km, (or about 6 trillion miles ) 41

• B. A Parsec is 3. 26 lightyears. • The distance to the star nearest earth is 4. 2 lightyears or 1. 3 parsecs. • It is a parallax measure of one arcsecond of space. 42

D. Constellations: • Stars that SEEM to be close together. People see an ‘image’ and make up stories • 88 recognized constellations (includes picture and space around/behind it) • (Measured in Right Ascension and Declination from ecliptic) 43

• Circumpolar constellations: p. 617 text and link to animation http: //www. astronomy. ohio-state. edu/~pogge/Ast 161/Movies/#circum • Big Dipper: p. 617 text • Seasonal Constellations: p. 618 -619 text and p. 714 -715 text 44