Venus and Jupiter to Converge in the Night Sky on June 30

6-17-15 Venus Jupiter
A crescent moon and the planets Jupiter (bottom) and Venus are seen in the sky over Buenos Aires on December 1, 2008. The two planets will reach a conjunction on July 1, 2015, appearing a third of a degree apart. Enrique Marcarian/Reuters

Prepare for a conjunction of planets. Venus and Jupiter are the two brightest celestial bodies after the sun and the moon, and in a couple of weeks they will appear side by side in the night sky. Every week since last winter, the two planets have appeared closer and closer to each other and are due to reach their closest point on June 30.

"But already they are something of a head-turning sight," says Alan MacRobert, senior editor of Sky & Telescope magazine. "If you hadn't been paying attention and get a clear evening and look to the west as the stars begin to come out and twilight fades down to night, you're likely to think, 'Hey, what's that?'"

MacRobert explains that planetary conjunctions, as they're called, happen often because the solar system is relatively flat, with all the planets orbiting on almost but not exactly the same plane, called the ecliptic. It's as though all the orbital paths are drawn on a piece of paper, he says. "Imagine microscopic little you on paper."

As the planets move around the sun, you see them around your head in a circle, he explains. When one passes in front of the other, they appear to be close together, as Venus and Jupiter will in several days' time.

On Friday, a thin crescent moon will be visible below Venus and Jupiter, forming a triangle of the brightest celestial bodies, save for the sun. The following night as well, the three bodies will form the points of a flattened triangle, with the crescent moon appearing closer in line with Venus and Jupiter, above and between them.

After the moon moves on, waxing and continuing in its orbit around the Earth, Venus and Jupiter will get closer and closer by day. They can be seen with the naked eye during mid- to late twilight. The ideal time to observe the phenomenon will vary, depending on one's location within a time zone.

From North America, the two planets will look closest on June 30. They'll be just a third of a degree apart, which is the visual equivalent to roughly the width of a chopstick held at arm's length. The next two conjunctions between Venus and Jupiter, though not nearly as close as the one on June 30, will take place on July 31 and October 26, MacRobert says.

But "looks in astronomy are deceiving. In no other realm of human experience are things so different than they appear," MacRobert explains. To the naked eye, Venus and Jupiter will appear to be almost touching. But they will not, in fact, be anywhere near each other; at the time of the conjunction, Venus will be 48 million miles away from Earth, and Jupiter will be 565 million miles away.

MacRobert warns that nearly every time there's a similar planetary event, there are people who claim that it's the end of the world, that there will be earthquakes and volcanoes, or that California will break off into the ocean. But "it never happens, and it won't this time," he says.

"What amateur astronomy is so cool for is it gets us out of our little anthill worlds right around us and look up into the larger universe and consider much bigger things going on all the time that we don't pay attention to," MacRobert says. It can, he adds, give us "a sense of perspective and humility."

Correction: The original article incorrectly stated that the date Venus and Jupiter will appear closest together is July 1. In American time zones, the conjunction date will be June 30, though the two planets will still appear nearly as close on July 1.