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The Earth

The Earth. Rotation of the Earth. The earth rotates about an imaginary line that passes through the North and South Poles of the planet.  This line is called the axis of rotation. Rotation – spinning of a planet or other body on its axis. Rotation of the Earth.

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The Earth

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  1. The Earth

  2. Rotation of the Earth • The earth rotates about an imaginary line that passes through the North and South Poles of the planet.  This line is called the axis of rotation. • Rotation– spinning of a planet or other body on its axis

  3. Rotation of the Earth • The rotation is counterclockwise. It is for this reason, that it seems that the sun: • Rises in the East (Earth moves west to east) • Is south at noon • Sets in the West • This axis is tilted 23 ½ ° • The rotation occurs over a 24-hour period • Speed of rotation = 1700km/hr at the equator, but varies by latitude due to Earth’s spherical shape

  4. Rotation of the Earth • This rotation causes the cycle of day and night • Since Earth is round and opaque, the sun can only illuminate one side at a time • This is why when it is • daytime in America, it is night in Australia

  5. Revolution of the Earth • The Earth also turns around the sun in an oval • path called an ORBIT at a speed of 29.75km/s • It takes 365.25 days for one complete revolution (a solar year) • Every 4 years the extra day is added to the calendar as February 29, this type of year is called a LEAP YEAR.

  6. Revolution of the Earth • Because the Earth’s axis is tilted, our planet is in different positions during the year, giving us 4 different seasons

  7. SEASONS • Seasons are caused by the combination of the Earth’s tilt and the Earth’s movement around the Sun. • When the tilt is pointing towards the Sun the Northern Hemisphere: - receives more of the Sun’s rays - receives more daylight hours - has summer • When the tilt is pointing away from the Sun, the Southern Hemisphere will: - receive more of the Sun’s rays. - receives more daylight hours - has summer

  8. Revolution of the Earth • The seasons are marked by solstices and equinoxes • — astronomical terms that relate to Earth’s tilt. • The solstices mark the points at which the poles are tilted at their maximum toward or away from the sun. (winter and summer)

  9. Revolution of the Earth • Summer solstice • shortest night of the year • sun is farthest north • first day of summer • June 21 in Northern hemisphere

  10. Revolution of the Earth • Winter solstice • longest night of the year • Sun is farthest south • first day of winter • December 21 in Northern hemisphere

  11. Revolution of the Earth • The equinoxes occur when the Earth is between solstices, it is spring and fall • Day and night have almost sameduration • all over the planet (12 hours each) • Sun is directly over the equator at solar noon two times a year.

  12. EQUINOX- Northern Hemisphere • Spring (vernal) equinox (March 21) • Fall (autumnal) equinox (September 21) Balancing an egg ONLY on the vernal equinox is a myth!!

  13. Why is it hot at the equator and cold at the poles? • At the equator, the sunlight hits the Earth’s surface at a 90˚ angle, which results in a more concentrated amount of sun in a given area. • At the poles, the same amount of sun is shining but not at a 90˚ angle. • The rays therefore get spread out over a larger area, making the sun less strong over any given area.

  14. MOTION OF THE MOON • Rotation: * It takes the moon 27 ⅓ days to rotate on its axis once. • Revolution: * It takes the moon 27 ⅓ days to make one complete revolution around Earth. THIS IS WHY THE SAME SIDE OF THE MOON FACES EARTH AT ALL TIMES!! The moon revolves around the Earth at a speed of about 3,500 km/hr.

  15. QUESTION: • The word “revolution” in astronomy refers to… • A) An object spinning • B) An object going around another object • C) An object traveling in the same direction forever • D) An object being pulled downward

  16. QUESTION: • Why do we, on Earth, always see the same side of the moon? • A) The moon doesn’t move • B) The moon revolves faster than it rotates • C) The moon rotates faster than it revolves • D) The moon revolves and rotates at the same rate

  17. DISTANCE OF MOON TO EARTH • APOGEE: when the moon is farthest from Earth (405,000 to 407,000 km apart) • PERIGEE: when the moon is closest to the Earth (360,000 to 370,000 km apart) • These differences affect the tides.

  18. MOON’S GRAVITY and TIDES • The combined gravitational pull of Sun and Moon results in higher tides and lower tides on Earth. • Spring tides – when tides are higher than normal – Moon and Sun are lined up – occurs twice a month • Neap tides – when tides are not as high or low as normal tides – Moon and Sun are are right angles Longer video on tides

  19. Phases of the Moon • The phases of the moon are caused by the changing positions of the sun, Earth, and moon • The moon is lit by reflections from the sun; the moon is NOT its own light source • Half of the moon is always lit by sunlight; however, the half of the moon that faces Earth is not always the half that is lit • The phase of the moon you see depends on how much of the sunlit side of the moon faces Earth

  20. QUESTION • Why does the moon light up at night (and sometime during the day)? • A) The moon reflects the light from Earth • B) The moon is its own light source • C) The moon reflects light from the sun • D) The moon reflects light from all the stars

  21. QUESTION: • How much of the moon’s surface is ALWAYS lit by the sun? • A) 100% • B) 0% • C) 75% • D) 50%

  22. MOON PHASES

  23. Moon Phases (view from space)

  24. New Moon First Quarter Waxing Crescent Waxing Gibbous Waxing = growing Waning = shrinking Full Moon Waning Gibbous Third Quarter Waning Crescent

  25. Question • Which way does the light “wax” or grow from as it crosses the moon’s face during the different phases? • A) Left to right • B) Right to left • C) Top to bottom • D) Bottom to top

  26. MOON PHASES • Moon phases – changing shapes of the Moon -New Moon – When the side of the moon is facing the Earth is dark; looks like there is no moon

  27. WAXING • WAXING PHASES – as the moon revolves around the Earth, a small part becomes visible. As the visible part increases, the moon is said to be waxing -crescent phase – first waxing phase; less than half of moon is visible - first quarter – half side of moon is visible

  28. WAXING GIBBOUS PHASE • As Moon continues in its orbit, more and more of the side facing Earth becomes visible • Waxing gibbous phase – more than half of the moon is visible

  29. FULL MOON • Full moon - the whole side of the moon facing the Earth is visible; half of the moon’s trip around the Earth is complete

  30. WANING PHASES • Waning phase - As the moon continues the move around Earth, less and less of the surface becomes visible • Waning gibbous phase:

  31. THIRD QUARTER (last quarter) • Half of the moon’s surface is visible

  32. WANING CRESCENT PHASE • Last phase of the moon:

  33. BACK TO FULL MOON • The Moon takes 29 ½ days to go through all its phases • This is a little longer than the time it takes for one revolution of the Moon around Earth because both of these bodies are also moving around the Sun (the moon spends the extra 2.2 days “catching up” because Earth travels about 45 million miles around the Sun during the time the Moon completes one orbit around the Earth.) • Moon must travel a little farther to get directly between Earth and the Sun

  34. Question • What moon phase is being shown in the picture? • A) Waning Crescent • B) Waxing Crescent • C) Waning Gibbous • D) Waxing Gibbous

  35. Question • If it takes 27.3 days for the moon to revolve around the Earth, that means it takes 27.3 days to go through all 8 moon phases. So, how many days are there, roughly, between each different lunar phase? • A) 1-2 days • B) 3-4 days • C) 5-7 days • D) 8-9 days

  36. Question • What lunar phase immediately follows the phase pictured below? • A) First Quarter • B) Third Quarter • C) Full Moon • D) New Moon

  37. DOES THE FULL MOON AFFECT HUMAN BEHAVIOR? http://www.scientificamerican.com/article.cfm?id=lunacy-and-the-full-moon&print=true

  38. PHASES OF THE MOON PROJECT DIRECTIONS

  39. Eclipses • Solar eclipse – (new) moon blocks sunlight – Earth is in moon’s shadow; occurs during new moon phase Order: sun, moon, earth • Lunar eclipse – Earth blocks sunlight from hitting (full) moon – moon is in Earth’s shadow; occurs during full moon phase Order: sun, earth, moon

  40. LUNAR ECLIPSE • Earth and moon can also cast shadows • Umbra – dark part or center of a shadow • Penumbra – the lighter part of the shadow between the dark part of the shadow and the full light • Lunar eclipse – passing of the moon through Earth’s shadow; occurs only during a full moon

  41. TOTAL ECLIPSES • Total Lunar eclipse – moon moves entirely into Earth’s umbra and all of the sunlight is blocked; entire face of moon darkens

  42. PARTIAL ECLIPSES • Only part of the moon moves into the Earth’s umbra; sunlight can still reach the moon so only part of the moon darkens.

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