Venus, Mars, Jupiter and Saturn are quite obvious any time they are above the horizon at night. But the fifth planet, Mercury, is so elusive that an often-repeated story claims that the great astronomer Copernicus never saw it (but this is likely a myth). Some stargazers even refer to it as the “shy planet.” The best time to spot it in the evening sky is when the planet is at its “greatest eastern elongation” (and in the morning sky when at its “greatest western elongation”).
This month Mercury will be 20 degrees east of the Sun on the evening of April 11th (recalling here that the Moon is about 1/2 degree in apparent size.) On that night the planet will be at its highest point above the western horizon, and then slowly over a period of days retreat back towards the Sun. Look for it low in the west after sunset. Having an unobstructed horizon will provide the best view and binoculars will aid in identifying it in the twilight.
Before closing, mention should be made that the annual Lyrid Meteor Shower also peaks this month—on the night of the 22nd into the morning of the 23rd. It’s an average display with perhaps 20 “shooting stars” visible at its peak. The crescent Moon sets early that evening, leaving dark skies the rest of the night. The meteors radiate from the tiny constellation Lyra, rising in the eastern sky after dark (use your Scientifics Star and Planet Locator to identify it).
— James Mullaney
Former assistant editor at Sky & Telescope magazine & author of 10 books on stargazing. His latest, Celebrating the Universe!, is available from HayHouse.com.