Question

Astronomy

1. Opposition is when a planet is in the opposite direction as the Sun from Earth. How can we use observations of greatest elongation and opposition to determine if a planet is inferior or superior?

2. Imagine building a model solar system by placing balls of various sizes on a table to represent planets. Is there any direction from which you could look at this model and always see the same relation between planet location that you described above? Explain?

3. Planets orbiting farther from the sun than Earth are known as superior planets, while those orbiting closer to the sun are known as inferior planets. Naked eye observations can tell us which are which.

4. Measure using a protractor the angle of greatest elongation for Venus.

5. Mercury is never seen farther from the Sun than 28◦. Is Mercury closer or father from the Sun than Venus? Briefly explain your reasoning,

6. Mars is a superior planet. What is the largest possible angle between the Sun and Mars as measured from Earth?

7. Opposition is when a planet is in the opposite direction as the Sun from Earth. How can we use observations of greatest elongation and opposition to determine if a planet
is inferior or superior?

8. What fraction of its complete orbit does Earth travel in 3 months.

9. Mars makes one orbit around the Sun in 1.88 years. How many degrees around its orbit does Mars move in 1 month?

10. Mars travels around the Sun in the same direction as the Earth. How many degrees does Mars travel around its orbit in 3 months’ time? Each month?

Answer 1

Solution -

Part 1 - to measure an inferior or superior planet, we first need to know the elongation between planet Earth and the Sun . Next lets say we need to measure whether Planet X is superior or inferior. All we need to do is to measure the opposition of that planet. If the opposition distance is more than that of earth, this means the planet is at more distance than the Planet Earth. Hence the planet is Superior if the opposition is more, and inferior if the opposition is less

To calculate using elongation distance, we will need the concept that a planet with orbit bigger than earth (superior planet) will have a bigger elongation than a planet with orbit lesser than earth (inferior planet). This is shown in the image

As we can see, elongation angle will be bigger for a planet outside Earth , and lesser for planet inside Earth. Using this angle we can tell which is a superior planet , or which is inferior planet. For reference , we can take angle of Earth as 90 deg

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Part 2 - If we make such a model as described above, there's a direction possible from where we can always see the same relation of planets. That is possible if we look from directly above the sun (in the center). This enables us to have the sun as reference point, then we can adjudicate the relative position of planet with respect to the sun

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Part 3 - Naked eye observations can not tell us which planets are inferior or which are superior because naked eye cant process the planets farther to us than the visible range. So if we cant determine where exactly the planet lies, we cant simply tell whether its superior or inferior. Naked eye observation of a miniature model can surely tell us which planet is inferior or superior just by a glance on it

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Part 4 -Elongation angle is the angel which gives us the maximum angle of how far away from the sun an the planet be seen.

To measure the angle of greatest elongation we will need a model. it can be done as is shown in the image