Venus shining brightly as the evening star over a dusky horizon.
Venus shines as the Morning Star at greatest western elongation and as the Evening Star at greatest eastern elongation.
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The inferior planets, Venus and Mercury, circle the Sun in orbits that create unique windows of visibility from Earth.

Venus can often be seen shining above the horizon before sunrise or after sunset. Mercury, on the other hand, is more difficult to spot: it’s smaller, less bright, and is often closer to the Sun’s glare.

What’s visible in your night sky now?

When both planets are at their furthest from the Sun from our point of view, they tend to be easier to see. These far points are known as greatest elongation.

Astronomical Events 2025

Dates of upcoming greatest elongations and other celestial events.

Measured in Angles and Degrees

For astronomers, elongation describes the separation between a planet and the Sun as seen from Earth. Scientists measure this positioning in degrees, and calculate it by measuring the angle between the sightlines from an observer to each object.

Zero degrees elongation means the planet is in conjunction, and it appears very close to the Sun, often with just a few degrees of north/south seperation. In rare cases, Venus or Mercury align perfectly with the Sun—from Earth; they can then be seen as a tiny dot passing in front of the Sun in what astronomers call a planetary transit.

Next Mercury transit

180 degrees elongation means that a planet is in opposition, or in a position directly opposite the Sun as seen from Earth. Venus and Mercury never reach opposition.

A Handy Guide to Measuring the Sky

Did you know that you can measure the distances between objects in the sky with just your hands and fingers?

Venus: 45–47 Degrees

Venus arrives at eastern and western greatest elongation points about every 584 days. During the planet’s synodic period, (the time needed for a planet to return to the same position in our sky, relative to the Sun), Venus alternates between shining as the Morning Star at greatest western elongation and the Evening Star at greatest eastern elongation.

Venus ranges from 45 to 47 degrees removed from the Sun at these events.

The hidden patterns of Venus’s movement across the sky

Mercury: 18–28 Degrees

Mercury, which is closer to the Sun than Venus, never gains more than 28 degrees of separation from our star as we see it.

With an elliptical orbit lasting only 88 Earth days, tiny Mercury arrives at greatest elongation more frequently than Venus. This planet’s synodic period lasts about 168 days.