Beginning this weekend, a rare alignment of five planets will be visible to skywatchers in the predawn sky with the naked eye.
Starting on Friday and lasting all throughout the month, Mercury, Venus, Mars, Jupiter and Saturn are to appear lined up in their proper orbital order from the sun on the eastern horizon before sunrise. That hasn’t happened since 2004, according to Sky & Telescope, a publication by the American Astronomical Society.
Mercury, being closest to the star, will appear lowest on the horizon, while Saturn will appear the highest in the night sky.
Best Time to Watch
To catch the rare phenomenon, it is recommended that sky watchers in the Northern Hemisphere head outside roughly 30 minutes before sunrise and choose a spot with unobstructed views of the eastern and southeastern horizons.
For those in the Southern Hemisphere, it’s best to stake out a location with unobstructed views of the eastern and northeastern horizon.
If conditions are clear the planets should be bright enough to see them with the naked eye, though Mercury, being closest to the horizon, will appear faintest in the sky at the beginning of the month. That might make it more difficult to spot without binoculars. As the month progress, however, it will become easier to spot, according to Sky & Telescope.
The magazine also noted that the best opportunity to see the spectacle may be on June 24 as Mercury should be up to about an hour before the sun and a crescent moon will also be visible between Venus and Mars, serving as a “proxy Earth.”
What Makes the Planet Alignment Rare?
While it’s common to see two planets appear close together in the night sky, the celestial phenomenon — known as a conjunction — is much more rare when more planets are involved. After June, the planets will begin to spread out in the predawn sky, “so much so that Venus and Saturn will make their exits as morning objects for most observers by September,” according to NASA.