This week, there will be a great planetary alignment, also known colloquially as a planetary parade, where all the planets in our solar system will be visible simultaneously in the night sky. Weather permitting, just after sunset, all seven planets will be visible in a line called an ecliptic.
Mercury and Saturn will only be visible for a short time after sunset, and a short time later, Neptune and Venus will join them below the horizon. Jupiter, Uranus, and Mars will be visible all night.
A great alignment is possible only when the planets are all relatively far from the sun, so they are visible at night, and all in approximately the same half of the sky, so they can be seen at the same time. It is a remarkable orbital coincidence – sometimes there are multiple great alignments in a year, and sometimes several years pass without a single one. A similar event isn't due to occur until 2040.
The unusual display will peak on February 28th. Apps like Night Sky and Star Watch can help identify the plane and aid novice and veteran skywatchers.
Previously: Newly proposed definition of "a planet" still excludes Pluto
