A unique opportunity for stargazers presented itself when Mercury, Venus, Mars, Jupiter, Saturn, Uranus and Neptune aligned on the evening of Feb. 28. The alignment of these seven planets is referred to as a “planet parade.”

Although Uranus and Neptune required binoculars or special equipment to see, Mercury, Venus, Mars, Jupiter and Saturn were visible through the naked eye.

According to space and science writer for CNN Ashley Strickland, effective viewing required a clear view of the western horizon and binoculars.

For those who couldn’t see the planets due to clouds or inclement weather, the Virtual Telescope Project offered an outlet for viewing through a live stream captured by a robotic telescope.

The appearance of alignment results when the planets gather on the same side of the Sun.

“Planet parades” occur through the way planets orbit the sun: along a flat, disc-shaped plane at different speeds and distances. Due to this, planet alignment is not uncommon because they orbit the sun roughly within the same plane. 

However, every few years it’s common for only four to five planets to align, rarely as much as seven.

According to Space.com, the next alignment of seven planets will not occur again until the projected year of 2040.