Can you help me on all this?

Question

Well I have a test and I have a studied guide I have to do,but we have to do the study guide in order to study but how if I put wrong answers Im going to study the wrong answers well if you all can help me with lots of question if yall kno.I did like 50 questions but still have long way to go.

Sorry for bothering so much =P
just put the number of the question and answer after
Thank you all for yall help

1.Explain:How at some times,planets appear to be traveling clockwise,rather than counterclockwise,in their orbits.What is this motion called?

2.Name the inner and outer planets and explain why they are classified in this way.

3. Earth's rotation is about 365 days.Sedna takes 1,825,000 Earth days to complete its rotation. How many Earth years is Sedna's orbit?

4.The diameters of Earth and mercury are 12,756 km and 4,875 km.How much smaller is Mercury than Earth?

5. Mercury is 57.9 million km from the Sun. What is this distance in astronomical units?

Answer 1

1) Retrograde motion, caused when Earth passes a slower planet as it orbits the Sun.

2) Inner = Mercury, Venus, Earth, Mars. They are small, rocky and close to the Sun. Outer = Jupiter, Saturn, Uranus, Neptune. They are large, mostly gaseous and far from the Sun.

3) It is Earth's REVOLUTION around the Sun that is 365 days. Rotation refers to Earth turning on its axis once a day. Just divide 1,825,000 by 365. Gee, do the math! OK, my calculator says 5,000.

4) Just subtract to get the difference in miles. This time you can do the math!

5) One A.U. is 150 million km, so divide. Again, do the math!

Answer 2

Nice answer by cambelp2002.

One slight addition: 1) what cambelp2002 describes is called "apparent retrograde motion" to distinguish it from real retrograde motion (an orbit where the object is actually going around the Sun in the opposite direction than the planets). None of the planets have retrograde orbits. There are some asteroids and quite a few comets with retrograde orbits.