Location, Location, Location Sailors relied on the astronomy (2000 B.C.) Universe ( ) Astronomy is the handmaiden to the sailor.

Transcription

1 The Universe Chapter 1 Why was Astronomy important to the ancients? Natural Clocks Motion of the sun, moon, planets and stars plant crops, harvest crops Location, Location, Location Sailors relied on the astronomy Astronomy is the handmaiden to the sailor Year 12 months 7 days a week a year Day 24 hours 60 minutes / hour 60 seconds / minute (2000 B.C.) Stonehenge Universe ( )

2 The use of Stonehenge as an astronomical observatory Apparent Path of the Sun The across the sky in the course of a year Plane of earth s orbit around the sun of ( circle of animals ) 12 equal divisions one each month Sun s movement through Zodiac Planets ( wanderers ) motion the that a planet makes in its orbit about the sun Celestial Location A used by astronomers to in Right ascension analogous to longitude Declination analogous to latitude Finding the North Celestial Pole the North Star Celestial Distance Circle Circle

3 Circle Angular size of an object determined by: Parallax the in of an object a of other objects The Parallax Angle Parsec The of astronomers Two Beliefs on the Existence of Stars Explanation for the Existence of Stars What evolutionists believe Sun Ordinary star Average brightness Massive, dense ball of gases Nuclear fusion reaction Origin of Stars Starts as a of gas Gravity forms protostar

4 Large Magellanic Cloud Protostar Begins as a cloud an accumulation of gases that will become a star Diameter Trillions of miles requires 1 x atoms Protostar Gravitational attraction atoms accelerate toward center temperature increases Forms a dense sphere diameter 1.5 million miles Stable star Gravitational attraction nuclear fusion begins 1.5 million miles begins stable life span

5 15 million degrees C Intense pressure 300 billion atmospheres Density 12x solid lead 1/3 mass of star Density of water Star Interior Star Interior 1/10 density of water surface emits visible light, UV radiation, and infrared 5,500 C Life Span of Stars Sun Converts 1.4 x kg of matter to energy every year has enough hydrogen for 5 billion more years Brightness of Stars for different of of objects as Brightness of Stars A to for the to the stars Standard distance 10 parsecs = 32.6 light years Brightness of Stars Absolute Magnitude Sun

6 Apparent magnitude = 26.7 Absolute magnitude = Distribution of Radiant Energy from Sun Not all energy from a star goes into visible light (KNOW) Star Temperature Star the of the star Hot = Moderate = white/yellow Cool = Stellar Types and Temperatures O B A F G K M Classification of Stars Star Types Classification based on: Henry Russell (United States) 1910 Ejnar Hertzsprung (Denmark) 1910 Hertzsprung-Russell Diagrams Examples Hertzsprung-Russell diagram Hertzsprung-Russell diagram H-R Diagram Hertzsprung-Russell diagram average size, stars brightness, temperature, and

7 Hertzsprung-Russell diagram Lots of surface area giving off light temperature Low density giants 100x bigger than sun but with same mass Hertzsprung-Russell diagram stars small (2x earth size) Very dense mass sun Life Stages Evolutionary theory Sun Nebula main sequence red giant white dwarf Hertzsprung-Russell diagram Cold lump of carbon (black dwarf) Hertzsprung-Russell diagram stars that over a period of time magnitude.001x 20x change period seconds to years 30,000 identified Hertzsprung-Russell diagram Cepheid Variable Stars Bright variable stars used to calibrate brightness with distance Measure distances to other galaxies

8 Relative Sizes of Stars The Life of a Star Evolutionary Theory Stable Star Nuclear Fusion to Low on hydrogen fuel Star contracts expansion reduced Collapse heats helium and remaining hydrogen Hydrogen fuses and layers expand Red Giant produced Red Giant surface temperature 4,000 K 1000x larger than main sequence Red Giant After many years helium fusion begins in core 100 million degrees required into in core red giant decreases in size (main sequence) Helium core transformed into carbon core

9 helium fusion begins in second shell expands to red giant again Outer layers begin to pulsate from constant cycle of contraction and expansion violent explosion blows off outer layers leaving hot core Planetary Nebula Blown-off outer layers of star adds dust and gas between stars Planetary Nebula Carbon core and helium fusion shell gravitationally contract to form a small dense white dwarf star White dwarf star cools from white, to red, then to a black lump of carbon in space Life Cycle of Star High Mass Main Sequence After blowing off outer shells core contracts carbon fusion begins 600 million degrees Kelvin

10 High Mass Main Sequence continues (plus other fusion reactions) until is produced Iron fusion produces no energy star out of fuel High Mass Main Sequence Star collapses and then violently explodes into a produces brilliant light in sky lasting for months Elements from Iron to Uranium formed in explosion 1987A Supernova (Before and After) High Mass Main Sequence Remains of compressed core after supernova > 1.4 solar masses - small, very dense with center core of > 3 solar masses black hole Neutron Stars Gravitational force collapses nuclei forcing protons and electrons together into neutrons super dense kg/cm 3 super small km -- neutron star that emits. the repulsive force of all subatomic particles

11 super super dense super super small 0 radius Explanation for the Existence of Stars What creationists believe Genesis 1:16 And God made two great lights; the greater light to rule the day, and the lesser light to rule the night: he made the stars also. Problems with Star Birth It is very difficult to get a gas cloud (nebula) to contract because gases naturally expand The catch is that the conditions required to compress the gas to that point seem to require the shock waves from the explosion of a previously existing star Chicken/egg dilemma Problems with Star Birth Almost every nebula is hundreds of times bigger than the critical size needed to form a stable star Precisely how a section of an interstellar cloud collapses gravitationally into a star is still a challenging theoretical problem Astronomers have yet to find an interstellar cloud in the actual process of collapse Fred Whipple, The Mystery of Comets, 1985 Problems with Star Birth If a nebula were to begin contracting it would spin and that would be a serious detriment to collapse because of the outward centrifugal force

12 The spin would produce a powerful magnetic field that tend to stop the collapse before a star could form The birth of a star has never been observed (KNOW) Despite numerous efforts we have yet to directly observe the process of stellar formation The origin of stars represents one of the fundamental unsolved problems of contemporary astrophysics. Charles Lada and Frank Shu, The Formation of Sunlike Stars, Science, 1990 When dark nebula (mostly dust) collide with emission nebula (fluorescent regions of gas) images like the Eagle Nebula form. The result is whitish areas appearing at the edges of the dark fingers of dust. Gases at such high temperatures will quickly disperse. Star death has been observed (KNOW) Supernovas A, or, is one of the most brilliant and powerful objects in the cosmos. Our galaxy, The Milky Way, should produce one supernova every 25 years. Supernovas cause a huge expanding cloud of debris Supernova Remnants and the age of the Universe How Evolutionists Respond

13 As the evolutionist astronomers Clark and Caswell say, Why have the large number of expected remnants not been detected? and these authors refer to The mystery of the missing remnants. Clark and Caswell, Monthly Notices of the Royal Astronomical Society, 174:267; cited in Ref. 1. How Creationists Respond There should be no mystery Psalm 19:1 says: The heavens declare the glory of God; and the firmament shows his handiwork. Supernovas declare His mighty power, but are still only finite expressions. The low number of their remnants is a pointer to God s recent creation of the heavens and earth. Star Degeneration Space universal trend of, not star formation Novas and supernovas Conclusion: the universe of created stars is slowly aging If black holes exist, they support this conclusion. Facts about our Sun Ideal size to support life on earth The sun is in an ideal environment A single star Position in Fairly circular orbit Distance from Milky Way center Exceptionally stable Solar flares Galaxies of and billions of stars that the of the Galaxy 200 billion stars galaxy Billions of galaxies 100 billion counted

14 Clusters of galaxies Galaxy Superclusters of galaxies Cluster of Galaxies (Virgo) Galactic Galactic Location of Galactic How close is the sun to the center of the Milky Way? The Sun is from center of the galaxy How big is the Milky Way? in diameter How long does it take the Sun to revolve around the nucleus? Sun would complete one revolution every 200 million years What is the Milky Way composed of? Thin concentration of gas, dust, and chemical compounds

15 Iron Carbon compounds Silicon compounds What is in the nucleus? red stars Little dust or gas 5,000 light year radius 1-2 light year radius What is in the halo? Groups of massive red stars in clusters What is in the disk? galactic clusters of stars Nearest neighbor dwarf spherical galaxy only 1,000 light years across 80,000 light years away Other Galaxies Milky Way has 11 satellite galaxies Other Galaxies Galaxy 2 million light years away in and to the Milky Way 100 billion stars Other Galaxies What is the farthest galaxy from Earth?

16 Galaxy 4C billion light years away Other Galaxies Other Galaxies What is the largest galaxy? Other Galaxies Abell x size of the Milky Way 100 trillion stars diameter of 6 million light years Classification of Galaxies Edwin Hubble (1926) Elliptical galaxies (20%) galaxies (50%) Barred galaxies (30%) Irregular galaxies Bell Telephone Labs 1920 s Wanted to set up a radio-telephone communication system across the Atlantic Sun s rays caused unwanted natural radio interference Set up research to study the problem

17 Radio Astronomy The first radio astronomy observations were made in 1932 by the Bell Labs physicist Karl Jansky who detected cosmic radio noise from the center of the while investigating radio disturbances interfering with transoceanic telephone service. Radio Astronomy Born 1933 also come from