This weekend provides a rare treat for stargazers. Well, planets, to be more specific. Mercury, Venus, Neptune, Saturn, Uranus and Jupiter will will appear to line up on the horizon shortly after sunset on Saturday, Feb. 28. Four of the six planets will be visible to the unaided eye, while the other two will require a telescope. The rare celestial occasion, a planetary alignment or planet parade consists of three to five planets and can occur every few months to every few years. However a six or seven planet parade is more rare. Here’s what to know about Saturday’s “planet...