Why Rare Planet Alignment Is 'Extra Special' Solar Event

This month, five planets visible to the naked eye are aligning in the sky in a "special" parade that hasn't been seen for 18 years.

The five planets, Mercury, Venus, Mars, Jupiter and Saturn—will be visible all at once throughout the month of June.

While seeing two or three planets close together in the sky—what's known as a conjunction—is a relatively common occurrence, having five together is "unusual," Robert Massey, the deputy executive director of the U.K. Royal Astronomical Society, told Newsweek.

But that's not all. There is something extra special about this particular planetary alignment, according to Diana Hannikainen, observing editor of Sky & Telescope magazine.

"And that is that the five naked-eye planets are strung across the sky in the same sequential order as they orbit the sun: Mercury, Venus, Mars, Jupiter, Saturn," she told Newsweek. "They just happen to be positioned in their physical orbits around the sun so that we see them so in the dawn sky."

The last time a similar lineup took place with the five planets in sequence was back in 2004 when they were visible in the evening sky, Massey said.

In order to view this alignment, stargazers will need to wake up before sunrise and look toward the east-southeast.

"They'll need to find an unobstructed horizon, such as a lake, or a field, or a hilltop with clear views to the horizon," Hannikainen said. "They should get into place about an hour, an hour and a half before local sunrise. Any morning that's clear between now and the end of the month is worth taking a peek."

"But there's one very special morning: June 24—that's when the moon will be positioned between Venus and Mars, serving as a proxy 'Earth,'" she added.

Observers will not need any special equipment apart from their own eyes to view the alignment, although binoculars are always handy, especially to pick out Mercury, which can be a bit tougher to spot at times, according to Hannikainen.

In general, people in the southern hemisphere will get the best view, as Mercury will be much easier to see there, Massey said.

"As far north as southern Europe and the southern United States, observers should be able to see all five planets fairly easily, but Mercury is really low and difficult when you get as far north as the U.K. and Canada," he said.

"The reason is that the tilt of the ecliptic—the imaginary plane of the solar system—has a very shallow angle up here in the June morning sky, whereas in the southern hemisphere it makes a steep angle to the horizon."