Why does neither Venus nor Mercury appear high in the night sky on Earth?
2 Answers
Both Mercury and Venus are inner planets.
Explanation:
So they will be always near sun. Maximum elongation mercury with Sun will be about 26 degree and Venus 47 degree.. WE can not see these planets when Sun is in the sky.The NASA diagram will explain it better. during the western elongation they will be visible during early mornings before Sunrise...Eastern elongations before sunset
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picture nasa gov
None of the planets appear high in the night sky because their orbits are nearly in the same plane.
Explanation:
The solar system is relatively flat. The Earth's orbit lies in what is known as the plane of the ecliptic. All of the other planets' orbits are within a few degrees of the ecliptic.
The elevation of planets is defined by Earth's axial title. This means that the planets are close to the horizon around the time of the equinoxes. They get to their highest elevation of around 23 degrees around time of the solstices.
Mars and the outer planets can be seen in the night sky. Mercury and Venus can never be seen in the middle of the night because they are closer to the Sun than the Earth. The reason being that during the night they are hidden behind the Earth.
The Sun is too bright for planets, other than Venus, to be seen during the daytime. An exception to this is during a total solar eclipse during which planets are often visible.
A planet's elongation is the angle the planet makes to the Sun when viewed from the Earth. The maximum elongation of Mercury is between 18 and 28 degrees, for Venus it is between 45 and 47 degrees. Mercury and Venus are only visible if their elongation is large enough for them to be seen before sunrise or after sunset.
When Venus is at its brightest and at its furthest elongation from the Sun it is visible during the daytime.
