Question

1. Which of the following would not be observed if you observed the sky without a telescope? (More than one answer can be correct).

Venus moves relative to the Sun.

Mars moves relative to the stars.

The starts rotate about a single point in the sky.

The stars move relative to each other.

The Moon moves relative to the stars.

2.Comparing theories by Ptolemy and by Copernicus. (More than one answer may be correct)

		Both could explain retrograde motion
		Copernicus' theory could explain retrograde motion, but Ptolemy's could not
		Ptolemy's theory could explain retrograde motion, but Copernicus' could not
		Neither of them could explain retrograde motion

Answer 1

Ans 1 When we observed sky with nacked eye. we unable to see

1) The starts rotate about a single point in the sky

2) The stars move relative to each other.

because they are too far away to us and we can see them only like a point but because of large distance from earth and our visible capacity we can not ibserve and study them

we can not determine there motion there size there shape and other thigs of us they like a bright fixed point in the sky

Ans 2) both gave retrograde motion but Copernicus' theory could explain retrograde motion, but Ptolemy's could not

a) Ptolemy and by Copernicus both theory give and explain retrograde motion.

Retrograde motion is automatically synchronized to conjunction/opposition and also automatically

occurs when the planet is closest to Eart.

b) But Ptolemy's theory could not explain retrograde motion,

No explanation is offered

for why planets come in two different types, with different motions for each

type.

c) Copernicus' theory could explain retrograde motion in natural way, he Copernican model produces retrograde motion in a natural

way when Earth passes, or is passed by, another planet. Retrograde motion is

automatically synchronized to conjunction/opposition and also automatically

occurs when the planet is closest to Earth. The sizes of all planetary orbits are fixed relative to Earth’s orbit , which provides a unique ordering for the planets The Copernican model also exhibits a harmony between orbital size and orbital speed: planets closer to the Sun orbit at greater speeds and thus haveshorter orbital periods.