A rare celestial event is coming to skies across the region beginning Saturday night as six planets prepare to put on an uncommon display. The astronomical phenomenon — often called a “planetary parade” — will give stargazers a chance to see multiple worlds appearing to line up across the evening sky at the same time.
While planetary alignments happen periodically, it is unusual for so many planets to be visible during the same viewing window. Under clear skies, observers across Pennsylvania and much of North America will be able to spot several planets without any special equipment.
Astronomers note that events featuring four or more visible planets occur only every few years, making this weekend’s alignment a particularly good opportunity for casual skywatchers and families to step outside and explore the night sky.
A planetary parade occurs when several planets appear grouped together along the same path across the sky. The planets are not actually forming a straight line in space. Instead, they orbit the sun on roughly the same flat plane — called the ecliptic — which causes them to appear aligned from Earth’s perspective.
Because all major planets travel along this same celestial track, they can occasionally cluster together visually, creating the illusion of alignment.
The planetary parade is expected to peak Saturday evening, when Mercury, Venus, Jupiter and Saturn will all be visible to the naked eye shortly after sunset. Uranus and Neptune will also be part of the lineup but will require binoculars or a small telescope to see clearly.
Clear skies are currently expected in Adams County, giving local residents a strong chance to view the event. Sunset is at about 6 p.m., and the best viewing window will begin about 45 to 60 minutes later, between roughly 6:45 and 7 p.m., when the sky grows dark enough for the planets to stand out.
For the best viewing experience, look toward the western sky and choose a location away from streetlights, trees, or buildings that might block the horizon. Allow your eyes about 15 minutes to adjust to darkness.
Venus will likely be the brightest object in the sky after the moon, shining low in the west. Jupiter will appear higher overhead, while Mercury and Saturn will sit closer to the horizon and may be harder to spot before they set.
Locations with open western horizons — such as rural fields or elevated viewpoints — will offer the clearest views.
Not sure whether you’re seeing a planet or a star? Planetary scientist Sara Mazrouei of Humber Polytechnic offered a simple rule of thumb: “If it’s twinkling, it’s a star. If it is not twinkling, it’s a planet.”
Stars appear to flicker because their light travels vast distances and is distorted by Earth’s atmosphere. Planets, being much closer, usually shine with a steadier glow.
Although smaller alignments occur fairly often, seeing multiple bright planets at once is less common because each planet moves at a different speed around the sun. Timing must be just right for several of them to appear above the horizon simultaneously after sunset.
Mercury — the fastest-moving and often hardest-to-see planet — will only remain visible for a short time before dropping below the horizon in the coming days, making early viewing especially worthwhile.
No telescope is required, but binoculars are actually excellent for viewing a planetary parade. It only takes a good view of the horizon and a little patience.
Featured image credit: Andrew McCarthy