Isaac Asimov (1920-1992), a legendary writer of science and science fiction, once noted in that the planet Mercury is rarely visible when it is truly dark.
"I suspect, in fact," he observed, "that many people today (when the horizon is generally much dirtier and the sky much hazier with the glare of artificial light than it was in centuries past) have never seen Mercury."
had two names, as it was not realized that it could alternately appear on one side of the sun and then the other. When visible in the evening sky, it was called Mercury and when appearing as a , it was known as Apollo. It was Pythagoras, around the 5th century B.C., who first recognized that Mercury and Apollo were the same celestial body.
A fine viewing window is now open
Mercury is indeed clever at escaping detection. It is said that the astronomer never saw the planet. Yet you can find it, if you know where to look. As the innermost planet, Mercury is usually masked by 's glare, so we must look for Mercury either soon after sunset, or in the case we are discussing here, just before sunrise.
On the morning of Tuesday morning (Aug. 19), Mercury reaches its greatest western elongation, meaning it's at its maximum apparent distance from the sun. To catch a glimpse, set your alarm for 45 minutes before sunrise and look low toward the east-northeast horizon. First, you'll spot brilliant Venus. About one and a half fist‑widths (approximately 15°) lower left of , look for a bright, yellowish point of light, Mercury.
Skinny moon points the way on Thursday
On Thursday morning (Aug. 21), besides Venus, there will be another celestial object to guide you to Mercury.
That will be our moon.