Planet ________ can never be seen on the meridian at midnight.

Planet ________ can never be seen on the meridian at midnight.

• A. Venus
• B. Mercury
• C. Mars
• D. Jupiter

Answer: (A)

The key idea is that the meridian at midnight points opposite the Sun. An object will be on that meridian only if it is roughly opposite the Sun in the sky, i.e., has a large solar elongation. Planets that stay close to the Sun can’t reach that opposite position, so they aren’t seen on the midnight meridian. Venus never gets far from the Sun in our sky; its greatest elongation is about 47 degrees. So it never appears opposite the Sun at midnight, and thus cannot be on the meridian then. In contrast, planets like Mars and Jupiter can reach positions opposite the Sun and be on the midnight meridian, making them visible around midnight.

The key idea is that the meridian at midnight points opposite the Sun. An object will be on that meridian only if it is roughly opposite the Sun in the sky, i.e., has a large solar elongation. Planets that stay close to the Sun can’t reach that opposite position, so they aren’t seen on the midnight meridian.

Venus never gets far from the Sun in our sky; its greatest elongation is about 47 degrees. So it never appears opposite the Sun at midnight, and thus cannot be on the meridian then. In contrast, planets like Mars and Jupiter can reach positions opposite the Sun and be on the midnight meridian, making them visible around midnight.