You could call it a cosmic encore. It so happens last June’s planetary alignment—which included eight planets in our solar system lining up—is seeing a repeat performance this December, leading into the new year. So, if circumstances prevented you from taking in the last “planet parade,” you'll have a few days to catch this one on the home stretch.
This month, eight planets—including Earth again—have fanned out across the starry expanse and currently appear as a grand, arced procession. Starting about 45 minutes after sundown local time, from low on the horizon, the planets arc southwest to east: Venus, Mercury, Saturn, Neptune, Jupiter, Uranus, and Mars in that order. Weather permitting, all save Neptune and Uranus will be visible to the naked eye.
Neptune and Uranus will still be visible but most likely you’ll need binoculars or a telescope to see them—which might also aid in sighting Mercury, as it will appear dim, hanging low on the horizon, competing with the dying twilight.
Moreover, a dainty young moon has already glitzed the lineup to complete the octet—the moon did last year too, becoming a placeholder for Earth in the planetary sequence from our vantage point. As the new moon fell on Dec. 23, the slender crescent rose to about 20 degrees over the horizon by Christmas, inserting into the series just left of and over Mercury, slightly lower than and to the right of Saturn. By the time of the first quarter, on Dec. 29, it will have ascended over the largest, most brilliant planet of the solar system, gas giant Jupiter, straddling atop the planetary procession.
The cosmic lineup last spring, falling on June 3, featured all five “naked eye planets” splayed out in the same sequence as their natural order from the sun—something that hadn’t happened in 18 years. That event occurred in the early morning hours, as opposed to evening this time; the grouping was tighter, forming a string spanning 91 degrees across the horizon.
The current planetary display is set to see 2022 through right to the end until Mercury drops sunward and is washed out in the lingering twilight, so you have a few days to take in the occasion. Or, if circumstances or weather make observation impossible with your own eyes, the event will be livestreamed on Dec. 28 at 11 a.m. Eastern Standard Time by the Virtual Telescope Project, put on by the Bellatrix Astronomical Observatory in Ceccano, Italy, and can be seen gracing the skies over Rome.