Sky & Telescope | 2015 Jun 18
[img3="On the evening of June 19–21, Venus and Jupiter — already close together in the evening sky — are joined by a thin crescent Moon. (Sky & Telescope diagram)"]http://www.skyandtelescope.com/wp-conte ... labels.jpg[/img3]All this month the two brightest planets, Venus and Jupiter, have been drawing closer together in the west in the evening twilight — and drawing all eyes toward them. Look west on a clear evening as dusk is fading, and you can't miss them. They're the brightest celestial objects after the Sun and Moon.
At the beginning of June, the two planets were 20° apart in the sky, about twice the width of your fist held at arm's length. Week by week, Jupiter and the stars behind it have gradually slipped lower in the evening twilight. But Venus, due to its rapid orbital motion around the Sun, has stayed high up. The resulting slow-motion convergence is setting the stage for a pair of dramatic sky sights.
** First, on the evenings of June 19th and 20th, you'll find Venus soon after sunset well up in the west. Jupiter is about 6° to its upper left and only 1⁄12 as bright. Farther to their upper left, and fainter, is Regulus, the alpha star of the constellation Leo. Adding to the scene is a thin crescent Moon: under the planets on the 19th, and left of them on the 20th. The view will be most dramatic on the 20th, when the two planets and the Moon will be bunched closely enough to cover with your fist.
Although they'll appear near one another, they're actually not. The Moon is closest to us, just 247,000 miles (400,000 km) away. Venus is 56 million miles (90 million km) from Earth, and Jupiter is 10 times farther out at just over 550 million miles (890 million km).
** A second, even more dramatic event occurs on June 30th, when Venus and Jupiter will appear so close together — just 1⁄3° apart — that they'll look like a tight, brilliant double star in the evening sky. You'll be able to cover both with the tip of an outstretched finger. ...
