1. Astronomy
It’s out of this world!

2. Rotation
Earth rotates or spins west to east or counterclockwise (ccw) on its axis.
Axis is tilted 23 ½ ⁰

3. Effects of Rotation Apparent motion of Sun, Moon and stars
Appear to rise in the east and set in the west

4. Day and Night Side facing Sun = day Side facing away from Sun = night
Areas near the poles may have several weeks in darkness or light

5. Length of day
About 24 hours to rotate = about 24 hours in a day
360⁰ in 24 hours = 15⁰ per hour
The farther east you are, the earlier the sunrise

6. Solar System
Milky Way Galaxy
The Universe

7. Our Place in the Universe
Our Solar System consists of our star, the Sun, and its orbiting planets (including Earth), along with numerous moons, asteroids, comet material, rocks, and dust

8. The Milky Way galaxy, a spiral galaxy, consists of the Sun and 200+ billion other stars.

9. The Universe is incredibly huge
The Universe is incredibly huge. It would take a modern jet fighter more than a million years to reach the nearest star to the Sun. Travelling at the speed of light (300,000 km per second), it would take 100,000 years to cross our Milky Way galaxy alone. No one knows the exact size of the Universe, because we cannot see the edge – if there is one. All we do know is that the visible Universe is at least 93 billion light years across. (A light year is the distance light travels in one year – about 9 trillion km.) The Universe has not always been the same size. Scientists believe it began in a Big Bang, which took place nearly 14 billion years ago. Since then, the Universe has been expanding outward at very high speed. So the area of space we now see is billions of times bigger than it was when the Universe was very young. The galaxies are also moving further apart as the space between them expands.

10. Revolution The Earth’s motion around the Sun
The orbit is elliptical (oval)
Objects that
revolve
around the
Sun are held
in place by gravity

11. Effects of Revolution
The length of a year = 365 ¼ days (every 4 years we add the four ¼ days to make 1 whole day = leap year)

13. Seasons (along with the tilt) Tilted towards the Sun = summer
Tilted away from the Sun = winter
A tilted towards
C tilted away
D and B not tilted so equal day and night

14. It is not the CLOSENESS to the Sun that causes the seasons…remember, we are CLOSER to the Sun in the winter and FARTHER from the Sun in the summer!
152,500,000
- 147,500,000
5,000,000 km

15. Position of the Sun in the sky
changes due to season
highest in the sky at noon
in the continental US the Sun is never
directly overhead, it’s in the
southern sky, so shadows at noon point
north

16. Position of the Sun in the sky changes
Summer = high in the sky = more direct rays = longer time to get to highest point = longer day = more heat
So…..it’s not the closeness to the Sun!

17. 4. Constellations Different constellations appear at different times of the year, so the earth MUST be changing it’s position in relation to the Sun.

18. Earth, Sun and Moon Positions
The positions of the Earth, Sun and Moon change in a regular, repeating pattern that produces predictable events:
Phases of the moon
Eclipses
Tides

19. Phases of the Moon Caused by the Moon’s orbit
Moon appears to change shape as it revolves around the Earth (more or less of the Moon’s surface can be seen)
The Moon takes 29 ½ days to complete one cycle of its phases (approx. one month)

20. Phases of the Moon Waxing = growing, moving towards full
Waning = shrinking, moving towards new

21. Eclipses Solar eclipse=
new moon casts shadow on Earth (only seen in a small area and lasts a few minutes)
Lunar eclipse= moon passes through Earth’s shadow (seen over large area and lasts a few hours)
Solar Eclipse
Lunar Eclipse

22. Tides
Due to the gravitational pull of the Sun and Moon, because the Moon is closer to Earth, its gravitational pull affects the tides more.

23. Spring and Neap Tides

24. Tidal Activity
Every 6 hours the tides change from high to low and back again…
At approximately what time would the next high tide occur?