These evenings in May, 2015 are a good time to look the planet Mercury. It reaches its greatest elongation – greatest angular distance, east of the sun – on May 6 (or May 7, depending on time zone). That means this world can now be spotted in the sunset direction as dusk ebbs into darkness. Cloudy tonight? No worries. Look for Mercury any evening in the first weeks of May.
At elongation, Mercury is 21 degrees east of the sun. The time of elongation is May 7 at about 5 UTC, but that time doesn’t matter. We all see Mercury in the west after sunset.
Mercury is the solar system’s innermost planet and orbits the sun inside of Earth’s orbit. That’s why Mercury always stays close to the sun in Earth’s sky. It’s often lost in the sun’s glare, but not now.