1. In which sequence are items listed from least
total mass to greatest total mass?
(1) solar system, Milky Way, universe
(2) Milky Way, solar system, universe
(3) universe, Milky Way, solar system
(4) Milky Way, universe, solar system

2. S LAR SYSTEM

3. We revolve around (orbit) the sun.
We know this because things in space look differently at different times of the year, like...
Seasons
Constellations

4. The diagram here represents the constellation Lyra.
Which statement best explains why Lyra is visible to an observer in New York State at midnight in July but not visible at midnight in December?
(1) Earth spins on its axis.
(2) Earth orbits the Sun.
(3) Lyra spins on its axis.
(4) Lyra orbits Earth.

5. When did the Solar system form?
4600 million years = 4,600,000,000 years = 4.6 x 106 years

6. Orbits result from motion of early solar system.

7. Terrestrial (inner) planets
Jovian (outer) planets
Asteroid
belt

8. WHY? All planets orbit the sun (and rotate) in the same direction.
In fact, moons orbit the planets in the same direction!
Closer ones always orbit faster.
WHY?

9. Gravity is stronger when objects are closer.
Which planet has a shorter period of REVOLUTION,
the Earth or Mars?
the Earth
More gravity
Less gravity
How many times has Jupiter orbited the sun during YOUR lifetime?

10. Notice any relationships?

11. If the average distance between Earth and the
Sun were doubled, what changes would occur in
the Sun’s gravitational pull on Earth and Earth’s
period of revolution?
(1) Gravitational pull would decrease and period
of revolution would increase.
(2) Gravitational pull would decrease and period
of revolution would decrease.
(3) Gravitational pull would increase and period
(4) Gravitational pull would increase and period

12. So, what about poor Pluto…