Mercury? Think of our innermost planet as the small, fleet guy in lane one of the quarter-mile track: he too is emerging from the other side of our star, slowly gaining on fast but “pudgy” Venus in lane two, and “fat” Earth, relatively plodding along in lane three (Jupiter is a model of obesity, speed-walking out in lane five!). Because Venus and Mercury both are inner planets-orbits inside Earth’s-they climb so many degrees above our horizon, but never appear overhead during the night sky. Mercury is currently climbing above Venus, but will reach the maximum point in its orbit relative to Earth’s (called maximum elongation), and in swinging around to go between us and the sun, will appear to begin rapidly falling once again toward the horizon (Venus eventually will too, but at a much slower pace, because its orbit is substantially larger than Mercury’s).
Now, with all the “technical” stuff out of the way…enjoy the show! Their positions, relative to one another, have been changing nightly over the past week. In the realm of stargazing, this is about as “animated” as we see celestial objects get. Enjoy while it lasts!
P.S. The above picture is another example of a planetary conjunction, this time a pairing: a rare conjunction of Venus and Saturn, in the pre-dawn sky, morning after Thanksgiving Day, 2012…it took more than a dozen shots to get this image! Five minutes later, the dimmer “star”, Saturn, was no longer visible on a subsequent shot, having succumbed to the brightening sky.