Mercury Emerges in Twilight
Venus has been center stage in the western twilight for several months, but it’s now joined by its rival Mercury just after sunset.
Mercury and Venus, looking West after sunset May 19, 2020 from Arvada, CO
Mercury is the closest planet to the Sun, with an orbit residing inside that of Venus much closer to the Sun. This smaller inner orbit means that it can’t stray as far as Venus on either side of the Sun, so it will never rise as high in the evening sky. And it’s further from Earth which makes it less bright.
While it’s harder to spot, if you know where to look you can catch it before it sets over the Front Range. Even at its furthest distance from the Sun it is almost entirely locked in twilight, but fortunately it is bright enough to spot through the dusk.
Your best chance of spotting it is to go out at sunset and note where the Sun crosses the horizon. Then immediately begin searching for Venus, which will appear first as it’s significantly brighter. Mercury will lie between Venus and the sunset, see the accompanying chart.
Also attached is a diagram showing the orbits of Venus and Mercury for comparison.
Relative orbits of Venus and Mercury
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