Venus

I have often joked that when I am asked a question that begins with “I saw this really bright thing in the sky…” my answer has a 90% chance of being right if I just say “Venus.” It is the third brightest natural object in the sky, outshone only by the Sun and the Moon. It appears as both the “evening star” and the “morning star”, but it never appears overhead, and it will never be visible at midnight. Understanding why this is so requires viewing the solar system from outside the Earth.

Venus, along with Mercury, is an inner planet, one that is closer to the Sun than the Earth. The image below shows the current (as of June 16, 2023) arrangement of the three planets closest to the Sun. The view is looking down on the Earth’s north pole.

Earth rotates on its north-south axis in a counter-clockwise direction as seen from above the north pole. As it does so, the sun will sink below the horizon in the west, followed a few hours later by Venus. Right now, Venus is the evening star, that bright object in the west most easily visible after sunset.

The closer a planet is to the Sun, the more quickly it moves in its orbit. Venus will “catch up” to Earth and pass it. A few months from now, in early October, it will be on the other side of the Sun as seen from Earth.

In October, as the Earth rotates, Venus will rise first in the pre-dawn sky. It will be the “morning star.” A few hours later, the Sun will rise.

But take a look at either of those images, and think about how far away from the Sun Venus can ever appear to be. There is a maximum—47 degrees to be exact—of angular distance from the Sun. It can NEVER appear in our sky at midnight, as any of the outer planets such as Mars can do. Here is the planetary arrangement at the next opposition of Mars in January 2025, when it is opposite the Sun in our sky and appears highest at midnight.

It all makes sense if we put the Sun at the center of our diagram, and not the Earth!