Conjunction junction, what’s your function? No, this isn’t an English lesson. It’s an astronomy lesson. Three planets will be aligned this weekend. Mercury, Venus and Jupiter should all be visible in the Western sky, peaking on Sunday evening about 30 minutes after sunset. The triple threat will be so bright, even city folks ought to be able to see it with naked eyes. Last time a triple conjunction formed was May 2011. Next time, mark your calendar for Oct 2015.