1 / 41

Chapter 1: The Cycles of the Sky

Chapter 1: The Cycles of the Sky. Constellations help astronomers know the positions of celestial objects. Zodiac signs. These coordinates can be used to describe the position of stars locally. zenith. Altitude. Azimuth. Angular distances of stars are measured in degrees.

jerrica
Download Presentation

Chapter 1: The Cycles of the Sky

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 1: The Cycles of the Sky

  2. Constellations help astronomers know the positions of celestial objects

  3. Zodiac signs

  4. These coordinates can be used to describe the position of stars locally zenith

  5. Altitude

  6. Azimuth

  7. Angular distances of stars are measured in degrees

  8. An imaginary Celestial Sphere surrounding Earth aids in navigating the sky

  9. What is wrong with this cartoon?

  10. Rotation vs. Revolution • Rotation represents the Earth’s spin on its axis. • This defines the length of 1 day. • 1 day= 24hours • Revolution represents the Earth’s orbit around the Sun. • This defines the length of 1 year • 1 year= 365.25 days

  11. Earth’s counter- clockwise rotation causes the Sun and stars to appear to move from East to West

  12. Motion of Stars at the North Pole

  13. Motion of Stars at the Equator

  14. Precession causes the position of the North Celestial Pole to change over a period of 26,000 years.

  15. UNLEARN

  16. Common Misconception The seasons occur due to the changing distance of the Earth from the Sun. When we are in our part of the orbit that is closer to the Sun, it is Summer, and when we are farther away from the Sun, it is winter This statement is NOT correct!

  17. LEARN

  18. Some Facts • When the Earth is physically closer to the Sun, it is winter time in the Northern Hemisphere, NOT summer • When the Earth is physically farther from the Sun, it is summer time in the Northern hemisphere, NOT winter • The Northern hemisphere and Southern hemisphere have opposite seasons from each other. Thus, Earth’s seasons are NOT caused by its changing distance from the Sun!!!

  19. Birds in the Northern Hemisphere fly south for the Winter... That is when it is winter in the Northern Hemisphere, it is summer in the Southern Hemisphere! ...which means that the Earth’s revolution around the Sun can not be the only explanation for seasons!

  20. The correct reason for the seasons: • the tilt of the Earth’s axis of rotation and • 2) Earth’s revolution around the Sun

  21. Earth is tilted!

  22. Summer solstice Equinox position Winter solstice

  23. The “altitude” of the Sun impacts how much energy is received on Earth.

  24. Concept Question What would be different if the Earth had no tilt?

  25. UNLEARN

  26. Common Misconception The phases of the Moon occurs because as the Moon orbits the Earth, the Earth casts a shadow on the Moon and blocks some or all of the sunlight from reaching the the Moon causing the amount of sunlight reflecting off the Moon to change. This statement is NOT correct!

  27. LEARN

  28. The correct reason for the phases of the Moon: Although half of the Moon is always lit by the Sun, we can only see the side of the Moon that is facing the Earth and only on that side does the amount of illumination change as the Moon orbits the Earth.

  29. Concept Question If the moon was between the Earth and the Sun, what phase do you think it will be? A) full B) new C) first quarter D) third quarter

  30. In other words ... • The Earth’s rotation on its axis determines the length of the day. • The moon’s orbit around the Earth determines the length of a month. • The Earth’s orbit around the Sun (revolution) determines the length of the year.

  31. Lunar eclipses occur only when the Moon crosses the ecliptic during the full phase

  32. Lunar Eclipses Lunar eclipse only happens when the moon travels through the Earth’s shadow Partial Partial Darkest part of the shadow = Full Intermediate part of the shadow =

  33. Lunar Eclipses The moon is not completely dark during a total lunar eclipse

  34. Lunar Eclipses The moon is not completely dark during a total lunar eclipse since small amount of light is bent around the edge of the Earth’s atmosphere!!!

  35. Solar eclipses occur only when the Moon crosses the ecliptic during the new phase

  36. Solar Eclipses Moon = 400 X smaller than the Sun, but 400X closer The moon has the same angular size as the Sun!

  37. Solar Eclipse from Space

  38. Solar Eclipse Annular Eclipse Partial Eclipse Total Eclipse

  39. Solar Eclipses Next total solar eclipse visible in the U.S. is August 21, 2017! Last annular eclipse visible in the U.S. was May 20, 2012!

More Related