Mercury is on course for a unique seven-planet alignment in the planetary parade.
In a show that will not be seen again until 2040, the seven will seem to form a straight line in the night sky. Mercury, Venus, Mars, Jupiter, Saturn, Uranus and Neptune lined up horizontally in a ‘planetary parade’. Photograph: Alamy/PA On the final day of February, seven planets will appear to align in the night sky in a phenomenon called a planetary parade. When multiple planets appear to line up in the night sky simultaneously, it is known as a "planetary hangout." "When several planets are visible in the sky si...