Astute skywatchers may have already seen the striking line of planets across the night sky in January. This week Mercury joins the queue. Now every other world in our solar system will be visible among the stars at the same time — if you know where to look.
According to Gerard van Belle, director of science at Lowell Observatory in Arizona, an alignment of seven planets is neither mystical nor particularly rare.
“On the scale of supermoon to death asteroid, this is more a supermoon sort of thing,” Dr. van Belle said. Still, the planetary parade, as the event is colloquially named, “makes for a very nice excuse to go outside at night, maybe with a glass of wine, and enjoy the night sky.”
Why are the planets aligned?
Whenever planets are visible in the night sky, they always appear roughly along the same line. This path, known as the ecliptic, is the same one that the sun travels along during the day.
This happens because the planets orbit around the sun in the same plane. Dr. van Belle likened the configuration to a vinyl record: The sun is in the center, and the grooves are the orbits of the planets around it.
