1 / 18

Seasons and Change

Seasons and Change. S1-4-05a Explain the apparent motion of the Sun, stars, planets, and the Moon as seen from Earth. S1-4-06a Differentiate between units of measure used for astronomical distances. KEY WORDS Rotate Revolve Axis Solstice Equinox Phase Planet Light-year

aerona
Download Presentation

Seasons and Change

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. Seasons and Change

  2. S1-4-05a Explain the apparent motion of the Sun, stars, planets, and the Moon as seen from Earth. S1-4-06a Differentiate between units of measure used for astronomical distances. KEY WORDS Rotate Revolve Axis Solstice Equinox Phase Planet Light-year Astronomical Units

  3. The Earth rotateson its axis once a day. At any time - half of Earth is in “day” and half in “night.” Earth rotates towards the East winter summer The Earth revolvesaround the Sun once a year. At any time - half of Earth is in “winter” and half in “summer.”

  4. Time-lapse photography to show the stars spinning as we rotate on our axis

  5. Our axis is tilted at 23.5o(degrees) This tilt and the curvature of the Earth is responsible for the variations in the Sun’s energy – and creates our seasons.

  6. Summer: not only more “direct” but also more hoursof the Sun’s energy Winter “indirect” energy Summer “direct” energy

  7. Spring Equinox (Mar 21) 12h and 12h Winter Solstice (Dec 21) Shortest Day Fall Equinox (Sept 22) 12h and 12h SummerSolstice (June 21) Longest Day

  8. What do you notice?

  9. Moon Rotation • Moon completes 1 rotation on its axis in the same time as it completes 1 revolution around the Earth (synchronous) • We always see the same side facing the Earth That’s why there is a “dark side” of the Moon • Orbit is elliptical • Tilted 5° • Mean Distance: 384,400 km

  10. Phases of the Moon • Shines only by reflected sunlight • Phase depends on the fraction of the sunlit hemisphere visible to us. Half facing the Sun is fully lit Opposite hemisphere is always dark

  11. Our solar system: Sun (a star) and all the objects in orbit around it. My Very Educated Master Just Showed Us Nine Planets Scientists estimate our solar system is 4.6 billions years old • Planet: a large collection of matter that is generally spherical and revolves around a star. • Planets / moons are nonluminous(don’t emit light) Remember, we can see moons and planets because light from the sun reflects off them

  12. Scientific Notation (x 10X) • Express very large or very small numbers • “Power of 10” equals the number of places the decimal was moved (+) large, (-) small 32 000 000.0 is 3.2 x 107 0.0000000055 is 5.5 x 10-9 2.6 x 105 is 260 000.0 2.6 x 10-5 is 0.000026

  13. Distance and the Universe • Common to use Astronomical Unit (A.U.) 1 A.U. = distance between the Earth and the Sun Common Distances: Sun - Pluto: ~ 40 AU Sun - Saturn: ~ 10 AU Sun - Jupiter: ~ 5 AU Sun - Mars: ~ 1.5 AU So Pluto is 40x farther away from the Sun than Earth Sun to the Earth: 1 AU = 1.5x108 km

  14. That’s 41,000,000,000,000 km! • Nearest star - 4.1x1013 km away from Earth! • This star is Proxima Centari • Light-year (LY): • The distance a beam of light travels in one year • Light moves outward fast – about 300,000 km/sec. • 9.46x1012 km /year = 1 light-year • P. Centari is 4.3 light-years away

  15. Distances can be deceiving: • Bright stars look close, but may be very far away StarApprox. Distance (LY) P. Centari4.3 Sirius 8.8 Betelguese 700 Rigel 900 Most distant known galaxy 15,000,000,000 Star light takes years to get to Earth – this delay means we are looking at old “images” – it’s like looking into the past…

  16. CAN YOU ANSWER THESE QUESTIONS? S1-4-05a: How does the position and motion of Earth produce day/night, the phases of the moon, and the seasons? S1-4-06a: How do astronomers measure the great distances in the universe? KEY WORDS Rotate Revolve Axis Solstice Equinox Phase Planet Light-year Astronomical Units

More Related