Patchy clouds will likely make it difficult for San Diego County residents to observe the rare sight of seven planets appearing to form a line in the sky on Friday evening, according to the National Weather Service. And it will be hard or impossible to see some of the distant worlds without binoculars or a telescope.

After dusk on Friday night, seven planets are expected to align in the night sky. But you'll need binoculars or a telescope to see them all.

Houstonians will be able to see seven planets in the sky this weekend in what's called a planetary parade. Unfortunately, however, some may not be spotted with the naked eye. Just after dark, it will be possible to view Mercury,