Six planets will link up before dawn on June 3 in what’s known as a planetary parade. But the spectacle won’t be as eye-catching as expected: Only two planets will be visible to the naked eye. Here’s what to know about this fairly common celestial event. WHAT IS A PARADE OF PLANETS? Our solar system’s planets zip around the sun at an angle. Every once in a while, several align on the right side of the sun to be visible across a narrow band of Earth’s sky. How common the phenomenon is depends on how many planets align and whether or not they are visible without binoculars or a telescope. A hand…