Solar System Gets its Ducks in a Row

Like a peacock spreading its feathers, the solar system's five brightest planets will fan out in a beautiful display at dawn through early July. Even more amazing, they'll be in correct order outward from the Sun starting with Mercury at the eastern horizon followed by Venus, Mars, Jupiter, and ending at Saturn. Standing under the spread will feel like looking out the window of spaceship Earth at our place in the cosmic order.

This rare event last occurred in the morning sky in December 2004. Turning to the evening sky, we saw similar planet lines in October 1997 and September 1995, but Mercury's elongation at those times was no more than 10°, restricting the view to sharp-eyed observers in tropical latitudes. For U.S. skywatchers the last similar grand spread took place in July 1957. Yikes, I was barely four years old!

Best dates

I encourage you to get up early at least one morning for a look. Invite friends. Bring the kids. There will be multiple opportunities for viewing, but the two choicest opportunities occur on June 24 (described above) and June 26, when Venus and the filament-thin Moon meet in conjunction. While it's not a once-in-a-lifetime event, the next opportunity won't be till March 2041. Call me impatient, but I'm not making any assumptions about the future.

The alignment is essentially a naked-eye event — the only requirements are clear to partly cloudy skies and an unobstructed east-northeastern horizon. That said, I strongly recommend you bring a pair of binoculars to help in digging out Mercury, which will hover low in the solar glow just a few degrees above the horizon for mid-northern and mid-southern latitude observers. Assuming an open view and haze-free air I think you'll see Mercury without optical aid. But a backup glass will guarantee you won't be shorted a planet. The other four will be much easier to spot.

You'll want to be outside a little early to get oriented and find a comfortable place to settle in for a view. An hour and 15 minutes before local sunrise is perfect. A lake, farmer's field, or a high lookout point with an unobstructed east-northeastern horizon makes an ideal location. Venus will be bright and low, with Mercury on the verge of rising at that time. All five planets will be best visible, depending on your latitude, from about 1 hour to 40 minutes before sunrise. Since that time is critical to planning, use this sunrise calculator to find out when the Sun comes up for your location.

Photo tips

Since many of us will want to photograph the span, you may want to do advance reconnaissance to include suitable foreground scenery. On June 20th, the pack extends across about 102° of sky, increasing to 116° by month's end. For a full-frame DSLR camera, you'll need at least a 12- to 14-mm lens — with horizontal fields of view of 104° to 112°, respectively — to squeeze them all in. Cropped sensor cameras require even shorter focal lengths. Since these lenses don't come cheap, a better alternative would be to take several photos of the scene with a standard lens and combine them into a single image using an imaging program like Paint (packaged with Windows 10/11), Mac OS Photos, or Photoshop. Check YouTube for videos showing how it's done.

Your creative hand will also be needed during post-processing because of the wide difference in lighting between the darker southern sky, where Mars, Jupiter and Saturn reside, and the bright belly of the eastern horizon, where the inner planets hide.

See every planet

Don't forget to include Earth in the lineup! You can do this by using the waning Moon as a proxy. Or just look around and admire the landscape. If you're a completist, you'll want to also search for Uranus and Neptune. They're up there, too, even if they screw up the order. Both are visible in either binoculars or a small telescope. And while we're at it let's include 4 Vesta, a representative from the main asteroid belt. Maps below provide the positions of these three additional objects.

How beautifully these five tiny lights demonstrate the essential flatness of the solar system. Looking up, you can practically see the ecliptic etched into the sky. When pointed out, even a neophyte will quickly grasp the "shape" of our neighborhood and Earth's place within it. And while flat Earthers will argue you to death about the sphericity of our planet or lack thereof, at least we can all agree this month that the solar system is as flat as a thin crust pizza.

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Read more about this and other celestial events this month in the June 2022 issue of Sky & Telescope.

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