On Saturday 12 July Mercury, the innermost planet, will reach its orbital position known as greatest western elongation. At that moment Mercury, the Sun, and the Earth, would be arranged in something close to approximating a right angle as this graphic shows.
From our perspective the orbits of Mercury and Venus appear to move from one side of the Sun to the other – out to the left (east) from the Sun to eastern elongation, then reverse and move westward (inferior conjunction) between the Earth and the Sun to western elongation. From there the inner planet moves eastward going behind the Sun (superior conjunction) and eventually reappearing on the eastern side of the Sun for an eastern elongation. Repeat over and over – do not stop!
The banner graphic at top of page shows the orbits of both inner planets with planets where they will be on the 12th. Mercury is at western elongation while Venus is past its own western elongation and is currently moving eastward toward the Sun and superior conjunction in a few months (October).
Mercury is currently visible as an ‘morning star’ over the eastern horizon at sunrise.
Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.