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This June brings Venus at her best showing since 2015. Find out why—and see Earth’s sister planet in her final weeks of brilliance. Here’s more information from Bob Berman.
You’ve surely seen Earth’s sister planet, that dazzling “star” in the west after sunset? The fact that the “Evening Star” hasn’t been this bright in 8 years is no accident. Some cool and easy math is part of this story. Because, so happens, Venus rotates slowly, taking 224.8 days to orbit the Sun. This means that 13 of its “years” (13 x 224.8) is the same number of days as 8 Earth years (8 x 365.25)! They both work out to 2,922 days.
Here’s why that’s significant. The concurrence of those two periods—13 Venus orbits and 8 Earth orbits—means that after eight years, we Earthlings see an exact duplicate of Venusian behavior. So just like this year, in 2015 we watched Venus shine brilliantly in the west the first half of the year and reach its very highest-up position in May and June when it didn’t set until after midnight – very unusual behavior for that twilight-hugging planet. And then it attained greatest brilliancy in late June and early July.
This June, Venus is easily the brightest object at night (other than the Moon). By late June and early July, Venus will be plunging down lower and lower each evening as it prepares to pass between us and the Sun.
So, this major eye-catching presence (Venus is one of only three celestial objects that can cast steady shadows) is now in its final weeks. It’s most spectacular just before it vanishes, as it now reaches a milestone we won’t see again until 2031—its greatest brilliancy AND ample height above the horizon.
If you have Venus visible in a dark rural place without artificial lights, spread a sheet on the ground and watch your shadow get cast by Venus-light! Notice the strange extreme sharpness of the shadow’s outline, a contrast from the familiar shadows cast by the Sun and Moon, which always have fuzzy borders.
Venus currently looks like a half-Moon through any telescope. Night by night it grows larger as it races a half million miles closer to Earth each day. By month’s end it will be big enough to display phases even through binoculars, as it gets larger while its crescent simultaneously grows thinner.
A special treat comes on the Summer Solstice (June 21). Look at the night sky about 40 minutes after the Sun sets for the crescent Moon? That bright “star” just to the Moon’s left is planet Venus. On the next evening, June 22, look for a dim planet Mars which floats halfway between the crescent Moon and bright Venus. See my June night sky guide for more information.