"This is, incidentally, why we sometimes observe planets appearing to approach closely to each other on the sky, as we view them along a line while they careen around the cosmic r

A rare parade of planets will light up the night sky throughout January. Six planets will be in alignment for the rest of the month – four of which will be visible with the naked eye, Preston Dyches, public engagement specialist at the NASA Jet Propulsion Laboratory and host of NASA's "What's Up" skywatching series, told ABC News.