An article in Sky & Telescope magazine from the American Astronomical Society says that throughout the month of June, shortly before the sun rises, sky-watchers across the globe will be able to see all five naked-eye planets, i.e. Mercury, Venus, Mars, Jupiter and Saturn stretching across the sky – in that order – from low in the east to higher in the south.
While 'planet parades' – more on them later – are not highly unusual, June's lineup is special because the planets will be arranged in their natural order from the Sun.
Mercury will be tougher to spot: Early in the month, viewers will need an unobstructed eastern horizon as well as binoculars to potentially see the little world.
As the month wears on, Mercury climbs higher and brightens significantly, making it easier to see, and thus completing the planetary lineup, the statement read.
The last time the five naked-eye planets were strung across the horizon in sequence was in December 2004. It is to be noted that this year, the gap between Mercury and Saturn is much shorter. There are several dates of note this month.
From June 3-4: On these two mornings, the five planets span 91° when the separation between Mercury and Saturn will be at its smallest.
According to Sky & Telescope magazine, the planetary lineup on June 24 morning is even more compelling. To begin with, Mercury will be much easier to snag, making the five-planet parade that much more accessible. The view will remain for about an hour, from when Mercury pops above the horizon to when the rising Sun washes it out of the sky.
Notably, the real bonus is the waning crescent Moon positioned between Venus and Mars, serving as a proxy Earth. By this time of the month, the planets are spread farther across the sky -- the distance between Mercury and Saturn will be 107°.
If it's cloudy on the dates of note, you still have all the mornings in between to take in the view of the five naked-eye planets adorning the southeastern horizon.
How does a 'planet parade' take place?
Although there is no official scientific term ‘planetary parade’, it is widely used in astronomy to denote an astronomical event that takes place when planets of the Solar System line up in a row in the same area of the sky, as seen by observers from Earth. Previous planet parades in recent years happened on April 18, 2002, and then on July 4, 2020. The next one is a little ways away by human standards – in 2040 – and the next is alllllll the way in the future, in 2854!
Can we ever see all the planets of the Solar System together?
On July 4, 2020, all the planets of the Solar System – Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune plus the dwarf planet Pluto – lined up on one side of the Sun at the same time.
The science of it
According to Starwalk.Space magazine, planetary alignment during a planet parade should not be taken literally. “In reality, planets never align in one perfectly straight line, as usually shown in the pictures. Since the Solar System’s planets do not all orbit perfectly in the same plane and swing about on different orbits in three-dimensional space, they will never be perfectly lined up,” says the magazine.