Mercury pops in and out view for only a few weeks at a time before disappearing in the solar glare. Its appearances are brief compared to the other planets because it orbits close to the sun. From mid-northern latitudes the fleet planet is always caught up in the glow of dusk or dawn and never visible in a dark sky.
Mercury’s been out at dawn the past couple weeks and remains visible very low in the eastern sky about 40 minutes before sunrise. Because it’s looping back toward the sun’s direction in a hurry, we only have a couple mornings left to see it. Mercury always grows brighter in the dawn sky the lower it sinks in the east because it’s waxing to full phase. Through a telescope it looks like a very tiny full moon. Tomorrow, it shines at magnitude –1.1 or just a little bit fainter than the brightest star, Sirius, which also happens to be visible at dawn.
Joining them both will be a thin crescent moon about 3 days before new. It floats three fists above and to the right of the planet. That’s not all. Through binoculars you might just be able to spy Regulus, Leo’s brightest star, in conjunction with the planet and located just 1° to its right (south).
Our next opportunity to see Mercury — a challenging one — doesn’t happen until late October when it pairs up with Jupiter very low in the southwestern sky at dusk. But there’s another exciting visual challenge happening Saturday morning (Sept. 8), again about 40 minutes before sunrise. That’s when an extremely thin crescent moon sits just 1.5° above Regulus. You may need binoculars for Regulus, but the moon should be an arresting sight. Aw heck, bring out the binos anyway to better appreciate the lunar delicacy before you!