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ASTRONOMY

ASTRONOMY. MARJORIE MANABAT. ASTRONOMY. Is the science that deals with the: Origin Evolution Composition Distance Motion of all bodies and scattered matter in the universe. HISTORICAL PERSPECTIVE. Geocentric orbit hypotheses Earth is at the center Sun orbits the earth

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ASTRONOMY

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  1. ASTRONOMY MARJORIE MANABAT

  2. ASTRONOMY • Is the science that deals with the: • Origin • Evolution • Composition • Distance • Motion • of all bodies and scattered matter in the universe

  3. HISTORICAL PERSPECTIVE • Geocentric orbit hypotheses • Earth is at the center • Sun orbits the earth • Mercury, Venus, Mars, Jupiter and Saturn revolves around the earth • Aristotle, Ptolemy • Aristarchus (3RD Century B.C.) • After some calculations done, proposed that the Earth revolves around the massive Sun in a heliocentric (Sun-centered) orbit

  4. GEOCENTRIC ORBIT HYPOTHESES

  5. HELIOCENTRIC ORBIT HYPOTHESES

  6. HISTORICAL PERSPECTIVE • 16th century: Nicolas Copernicus • Mathematician and an Astronomer • Expanded the HELIOCENTRIC MODEL • Starting point of Modern Astronomy (Scientific Revolution)

  7. HISTORICAL PERSPECTIVE • 1609 Galileo Galilei • Italian mathematician • Telescope • Observations using the telescope can prove the heliocentric model

  8. HISTORICAL PERSPECTIVE • Galileo Galilei • Observations: • Appearance and size of Venus varied as its position change relative to the Sun and Earth • Isaac Newton • Explained the presence of a Force that keeps the planets in their orbits around the Sun -- gravity

  9. ORIGIN • The universe is thought to be somewhere between 11 to 20 billion years old • Based on the rate at which distant galaxies are moving away from us • Earth • is a small, rocky planet that circles the Sun, one of the hundreds of billions of stars making up the Milky way galaxy.

  10. ORIGIN • Milky way Galaxy is just one of the billions of Galaxies in the universe. • Current computations = 14 billions years • Age may change as scientists learn more about the characteristics of the most distant galaxies and stars • GALAXY: refers to a large assemblage of stars, interstellar gas, and dust. These are breeding grounds of stars

  11. THE BIG BANG THEORY

  12. THE BIG BANG THEORY • The universe began 11 to 20 billion years ago with a massive and rapid inflation, called the Big Bang • Before that, they was no space nor time

  13. DETERMINING THE AGE AND SIZE OF THE UNIVERSE • LUMINOSITY • Measurement of brightness of clusters of distant stars • Cepheid variables • Specific class of stars; pulsate in brightness • Cepheid variables’ average brightness by measuring the time between the periods of maximum and minimum brightness. • Use the brightness to calculate our distance from the star

  14. DETERMINING THE AGE AND SIZE OF THE UNIVERSE • LUMINOSITY • The dimmer the star, the farther away it is from the observer • Edwin Hubble – used data on these stars to show that the universe extends far beyond the Milky Way Galaxy. • The distance to a cluster of these stars was not constant but was steadily increasing  our universe is expanding.

  15. DETERMINING THE AGE AND SIZE OF THE UNIVERSE • Doppler Effect • The changing frequency due to the relative motion of a source of sound • Hubble used the Doppler effect on light to estimate Earth’s distance from faraway stars • In space, the velocity of light is constant = 3 x 108 meters per second (300,000 km/s) • White color = combination of different colors • Violet and blue = shortest wavelength • Red = longest wavelength

  16. DETERMINING THE AGE AND SIZE OF THE UNIVERSE • Doppler Effect • “Red shift”: a phenomenon; shifting of light’s wavelength towards the red. • By calibrating the red shift data with information on the brightness of Cepheid variables, scientists were able to use the magnitude of the red shift to estimate the speed that individual stars were traveling away from us.

  17. DETERMINING THE AGE AND SIZE OF THE UNIVERSE • Doppler Effect • Hubble said: All stars are moving away form us, and the farther away the star, the greater the red shift (the faster they are moving away) • Astronomers use the amount of red shift to calculate the distance to the farthest galaxies.

  18. DETERMINING THE AGE AND SIZE OF THE UNIVERSE • Measuring distances in Light Years • One light year is the distance that light can travel in one year • Equivalent to 9,500 billion kilometers • Our galaxy is 150,000 light years across • Nearest star to the Sun = 4.3 light years away • Allows us to identify the age of objects • It takes 1 billion years to receive light from a star that is 1 billion light years away. • If we’re looking at a star, we are actually looking at light generated at least 13 billion years ago

  19. The birth of Stars • Interstellar space • Contains: • Primarily Hydrogen • To a lesser degree: ammonia, ethyl alcohol, interstellar dust (carbon and silicates), sometimes coated with frozen ice of water, carbon dioxide, methane and ammonia. • Dust particles • The density at the center increases dramatically as matter is scrunched together with an accompanying rise in temperature and pressure.

  20. STARS AND PLANETS • How stars formed? • The Big Bang created clumps of cosmic debris throughout the universe  galaxies • Within the galaxies, clouds of dust and gas coalesced, increasing their mass and pulling in adjoining material.  nuclear fusion  releases energy – causing it to glow and casting radiation outward in space

  21. STARS • Vary in size and longevity • High-mass Stars: • Hydrogen fusion occurs at a faster rate; • brighter • have short lives • Low-mass Stars: • Hydrogen fusion occurs at a much slower rate; • dimmer in brightness; • live longer

  22. HOW STARS ARE FORMED? • Made up of Hydrogen and Helium • Heat comes form the nuclear fusion of four Hydrogen atoms to form a single Helium atom. • When the Hydrogen core that has been converted to Helium core contracts due to gravity, it will raise the temperature  igniting both the helium in the core and the unfused Hydrogen outside the core  star expands  RED GIANT

  23. HOW STARS ARE FORMED? • Our sun will eventually reach this stage about 5 billion years from now • Sun will swell • Sun becomes more luminous • It will cause temperatures on the Earth to escalate • Stripping the Earth of its Atmosphere • Boiling the oceans dry

  24. HOW STARS ARE FORMED? • The expanding red giant sun will envelop Earth and will continue to expand until the Helium is exhausted • Helium  Carbon • If the star is not hot enough to fuse with carbon, the star will shrink  PLANETARY NEBULA • The outer layers of the sun will gradually disappear leaving a cool, shrinking core “White dwarf star” (same size as Earth) • Billions of years later, all heat will be lost, and the sun will become “black dwarf star”

  25. HOW STARS ARE FORMED? • Giant stars burn brightly for “just” 10 – 20 million years before they die • Death throes: • Marked by a Super nova • A massive explosion that fuses together elements heavier than iron and blasts them throughout the universe.

  26. HOW STARS ARE FORMED?

  27. HOW PLANETS FORMED?

  28. HOW ARE PLANETS FORMED? • Just like every other star, when the Sun was formed, it was surrounded by a rotating disk of leftover debris. • Clumps of this debris formed the planets. • Lighter gases (Hydrogen & Helium): outer and colder parts of the planet system  icy gas-rich planets • Heavier elements (Carbon, Oxygen, & Iron) form the rocky inner planets

  29. HOW ARE PLANETS FORMED? • Planets travel around their stars in a consistent orbital direction, providing evidence that all the planets formed from the same swirling mass of gas and dust.

  30. HOW ARE PLANETS FORMED? • At present, 160 extra solar planets existing beyond our solar system • Hubble Space Telescope

  31. SOLAR SYSTEM • Sun = 99.8% of the mass of our solar system • The sun rotates once a month • Differential rotation: the equator region rotates faster than the polar region  causes disruptions in its magnetic field • Producing “Sun Spots” and “Solar flares”

  32. SOLAR SYSTEM • SUN SPOT • Are dark blotches on the Sun’s outermost layer • Slightly cooler areas of the Sun’s surface • Source of intense lines of magnetic force. • Number: varies

  33. SOLAR SYSTEM • SOLAR FLARE • Are intense pulses of X-rays and ultraviolet radiation • Often associated with Sun spots • Can affect activities on Earth

  34. SOLAR SYSTEM • Space weather • Dominated by the Solar wind • A constant stream of charged particles emitted from the Sun’s magnetic field • 450 km/s

  35. SOLAR SYSTEM • Heliosphere • The region of space affected by the solar wind • Extends far beyond the planets of our solar system • Earth has its own magnetic field that deflects the solar wind around our planet • Intense streams of charged particles can disrupt Earth’s magnetic field, generating electrical currents that result in power surges

  36. SOLAR SYSTEM • 1989 Eastern Canada and Northeastern US lost power for 9 hours • Due to a powerful solar storm that coincided with a solar maximum (a lot of solar spots) • Aurora borealis and australis • Formed by the interaction of the solar wind with Earth’s magnetic field

  37. PLANETS • As of 2006, Sun is the center point of a system of 8 planets • Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune • Terrestrial planets: • Smaller planets; Mercury, Venus, Earth & Mars (4) • Nearest to the Sun • Share similar characteristics

  38. PLANETS • Jovian planets • Larger outlying planets (4) • Jupiter, Saturn, Neptune and Uranus • Pluto – member of the dwarf planets

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