A few millennia ago, civilizations depended on their knowledge of the stars to navigate the seas, plant and harvest crops, and keep time in general. In addition to the fixed stars – those points of light that dependably reign the celestial sphere – they recognized there were stars that wandered. As early as 14 BC the Babylonians had already observed the 5 "ancient" planets, naming them after their deities. Today we know them as Mercury, Venus, Mars, Jupiter, and Saturn.
The greatest scientific advances have been founded on observation, but our observational skills now are more often tasked with arguably smaller objectives: is the stoplight red or green? is that the exit sign? where did I put my glasses? As light pollution clouds our vision of the sky above, we feel fortunate when we notice the brightest objects in the night sky, whether it's Arcturus or Sirius, the constellation Orion, or Venus, Mars, Jupiter and Saturn.
Perhaps it's only for geeks like me to get excited at a chance to see Mercury. Because Mercury is never farther than 28º from the Sun, not only is Mercury rarely observable in the night sky but, due to the angle of Earth's ecliptic, it's even harder to see in northern temperate latitudes. Still, I like to imagine ancient astronomers getting a little excited too. After all, the Babylonians and even the Greeks gave Mercury two different names, one for his evening apparition and another for his morning apparition; for some time, they may not have been certain it was one and the same planet.
At Indigo Night, we call Mercury "elusive," our way of capturing the trickster-like quality of this planet that slips back and forth like the ancient messenger between the regnant Sun and the night sky. And for the next few days, given clear skies at sunset, you too can exercise an observational skill honed by our ancestors as Mercury shines during its greatest eastern elongation from the Sun.
Let tonight's slender waxing crescent moon be your guide to locating this fellow member of our solar system, as both will be visible after the Sun's rays have disappeared. Start looking to the west-south-west about 45 minutes after the sun has set this evening. If you're fortunate, you'll find the moon, illuminated 2%, in Capricornus just slightly to the west of Mercury in Aquarius. If tonight fails, look again Saturday. The moon will be higher, following Mercury, but the arch of its "bow" will be pointing in the right direction.