The planets of the solar system were lined up in the night sky on Wednesday, visible from Earth, in what is known as the “planetary parade”.
The event, also visible on Tuesday night, made Mercury, Friday, Mars, Jupiter and Saturn better visible to naked-eye skywatchers. With a pair of binoculars or binoculars, Uranus and Neptune can be seen.
A planetary parade is not a very rare event – it happens at least every two years. Actually, the alignment of the eight planets happened last June.
To view the event, it is recommended to look south after sunset. From east to west, the planets appeared in this order: Mars, Uranus, Jupiter, Neptune, Saturn, Mercury, Venus.
“People should look south 30 to 45 minutes after sunset, when they’re closest to the horizon to catch Mercury and Venus,” says Vahe Perromian, professor of astronomy and physics at the University of Southern California. “Jupiter, Saturn and Mars are visible from the southeast to the east after dark.”
Perumian told CBS News that planets can appear together in the same part of the sky as they orbit the sun.
“Mercury completes one orbit in 88 days and Venus in 225 days. The outer planets move very slowly: Jupiter takes 12 years to go around the Sun, Saturn 29 years,” he said. “So, as far as Jupiter and Saturn are concerned, unless they are on opposite sides of the Sun from our point of view, the rest of the planets will eventually line up.”
Neptune and Uranus take 165 years and 84 years, respectively, to orbit the Sun at the same time that they are visible, a major achievement.
Both planets “spend a significant amount of time on opposite sides of the Sun from our point of view,” Perumian said.
On Wednesday night, Uranus and Neptune were relatively close, but because Uranus orbits the Sun twice as fast as Neptune, the planets would be farther apart, he said.
As a result, “both planets will not be visible in the night sky at the same time for decades,” Perumian added.