Discovering the Universe Chpt. 2

at what configuration (superior conjunction, greatest eastern elongation, etc) would it be best to observe Mercury or Venus with an Earth-based telescope? At what configuration would it be best to observe Mars, Jupiter, or Saturn? Explain your answers.

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How long does it take Earth to complete a sidereal orbit of the Sun?

365 1/4 days

How did Copernicus explain the retrograde motion of the planets?

Copernicus explained retrograde motion from the point of view of the heliocentric model of the Universe. According to the heliocentric model, retrograde motion was as a result of the fact that all the planets revolved around the sun and this occurs naturally where by planets further from the sun rotate more slowly in their circular orbits than those closer to the sun.

which planets can never be seen at opposition? Which planets never pass through inferior conjunction?

Inferior planets (Mercury and Venus) can never be seen at opposition because these are the only planets that can have the earth between them and the Sun. The Superior planets (Mars, Jupiter, Saturn, Uranus, and Neptune) never pass through inferior conjunction because they cannot be in between the Earth and the Sun.

who wrote down the equation for the law of gravitation?

Newton

what are the synodic and sidereal periods of a planet?

The Moon's synodic period is the time between successive recurrences of the same phase; eg: new moon to new moon. sidereal period is the time it take one body to make a complete orbit around the Sun

which of the following planet takes the longest time to orbit the Sun? a. Earth b.Uranus c.Mercury d. Jupiter e. Venus

Uranus

What most accurately describes the shape of Earth's orbit around the Sun?

elliptical

What is a sun centered model of the solar system called?

heliocentric