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Unit 1 Notes

Unit 1 Notes. Astronomy. BIG BANG THEORY. The Big Bang. 15 Billion Years Ago Universe was created when a tiny, super dense, super hot mass exploded and began expanding rapidly. Eventually cooled and formed into stars and galaxies Universe is constantly expanding in all directions.

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Unit 1 Notes

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  1. Unit 1 Notes Astronomy

  2. BIG BANG THEORY

  3. The Big Bang • 15 Billion Years Ago • Universe was created when a tiny, super dense, super hot mass exploded and began expanding rapidly. • Eventually cooled and formed into stars and galaxies • Universe is constantly expanding in all directions

  4. Where is earth in the universe? • Universe is made of galaxies • Galaxies are made of stars • Some stars have planetary systems • Earth is a planetary body revolving around the sun Revolves around Part of Part of Earth Sun Galaxy Universe

  5. Where is earth in the universe?

  6. Our Solar System Revolves around the Sun • The sun is a star • Through gravity planets revolve around the sun. Sun Song - http://www.youtube.com/watch?v=3JdWlSF195Y

  7. Barycenter ~ Center of gravity

  8. Barycenter • The center of mass of two or more bodies, usually orbiting around each other, such as the earth and the moon. • Earth & moon connected by gravity pulling them together. • Center of mass is almost center of sun

  9. Barycenter • Barycenter of sun & Jupiter As Jupiter revolves around the sun, the sun is revolving around the slightly off-center point.

  10. Barycenter* As seen from above, a large planet orbits a star (or rather they both orbit their shared center of mass, their barycenter) As seen from the side, a large planet and star orbit their shared center of mass, or barycenter.

  11. How Many Planets Are In Our Solar System?

  12. Planet Density Terrestrial Planets are more dense than the gas giants

  13. How far is the earth from the sun? • 1 Astronomical Unit (1 Au) • 1 Au = 150 Million Kilometers • 150,000,000 Km = 93,000,000 miles • Other distances in space are determined in reference to the distance from earth to the sun

  14. Astronomical Unit (Au)

  15. Formation of Earth Earth and the planets formed about the same time. Nebular Hypothesis • Our solar system formed from a rotating cloud called a solar nebula.

  16. Formation of the Solar System  Nebular Theory • A nebula is a cloud of gas and/or dust in space. • According to the nebular theory, the sun and planets formed from a rotating disk of dust and gases.

  17. Formation of the Universe

  18. Formation of the Solar System  Planetesimals • Planetesimals are small, irregularly shaped bodies formed by colliding matter that formed planets.

  19. Earth-Sun Relationships  Earth’s Motions • Earth has two principal motions—1) rotationand 2) revolution.  Earth’s Orientation • Seasonal changes occur because of Earth’s tilt and Earth’s position relative to the sun continually changes as it travels along its orbit.

  20. 3rd Motion Precession • Earth’s Tilt = 23.5degrees • Wobbles like a top • Slight movement (over 26,000 years) between 22 – 25 degrees

  21. 4th Motion Nutation Wobbling 1/2degree over 18 year period. Due to Moon Causes a slight change in seasons

  22. Tilt of Earth’s Axis Animation – Seasons and Ecliptic http://www.learner.org/jnorth/tm/mclass/eclipticsimulator.swf

  23. Earth-Sun Relationships  Solstices and Equinoxes • The summer solstice is the solstice that occurs on June 21 or 22 in the Northern Hemisphere and is the “official” first day of summer. • The winter solstice is the solstice that occurs on December 21 or 22 in the Northern Hemisphere and is the “official” first day of winter.

  24. Earth-Sun Relationships  Solstices and Equinoxes • The autumnal equinox is the equinox that occurs on September 22 or 23 in the Northern Hemisphere. • The spring equinox is the equinox that occurs on March 21 or 22 in the Northern Hemisphere.

  25. Length of Daylight  The length of daylight compared to the length of darkness also is determined by Earth’s position in orbit.

  26. Solstices and Equinoxes

  27.  Johannes Kepler • Kepler discovered three laws of planetary motion: 1. Orbits of the planets are elliptical. 2. Planets revolve around the sun at varying speed. 3. There is a proportional relationship between a planet’s orbital period and its distance to the sun.

  28. Kepler’s Laws • Path of each planet around the sun = ellipse *Sun at one of the foci

  29. Kepler’s Laws* 2. Planet speeds up as it is closer to the sun, slows down further away

  30. Kepler’s Laws

  31. Kepler’s Laws 3. The length of time it takes a planet to orbit the sun (orbital period) & its distance to the sun are proportional

  32. Kepler’s Laws T2 = AU3

  33. TIDES* • Daily changes in the elevation of the ocean surface. • Result from the gravitational attraction exerted upon Earth by the moon and to a lesser extent the sun.

  34. TIDES • Moon revolves around Earth every 29.5 days • FORCES • Gravity – attracts Earth and moon to each other • Inertia – tendency of moving objects to continue in a straight line.

  35. TIDES Side of earth near moon Gravity > Inertia Tidal bulge toward moon Side of the Earth away from moon Inertia > Gravity Tidal Bulge

  36. Phases of the Moon

  37. Phases of the Moon

  38. TIDES Moon position changes moderately each day Tidal bulge stays in place Earth rotates through tidal bulge 2 high tides & 2 low tides per day

  39. Spring Tides STRONG Sun, Earth, & Moon are in a line. Occur at full moon and new moon

  40. Neap Tides Weak Tides Sun & Moon are perpendicular Occur during Quarter Moons

  41. Phases of the Moon & Tides

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