Have you noticed that bright shining ‘star’ in the morning skies? At this time of the year you could be thinking I am referring to Sirius, the brightest night time star. While Sirius, no kidding, has an apparent magnitude of -1.4 it is out shined by the inner planet Venus now rising about 2-3 hours before sunrise local time. Venus currently has an apparent magnitude of -4.54 and coincidentally Venus is at its greatest brilliance.
Venus monthly: January-December 2015
This is not the first time that Venus has been at its greatest brightness as this point in Venus’s orbit occurs as a function of the planet’s orbital position relative to the Earth and the Sun. Venus increases in its apparent size as it moves from superior conjunction, behind the Sun through eastern elongation to inferior conjunction. During this time Venus goes through phase changes starting with a waning gibbous phase following superior conjunction to a new phase at inferior conjunction. At this point Venus is at its greatest apparent size however we will not see Venus until it moves away from inferior conjunction. As Venus moves toward western elongation and then to superior conjunction its apparent size decreases while it goes from a large crescent shape to a smaller waxing gibbous phase.
Venus was at inferior conjunction this past August 15th so it was last at its greatest brightest on July 12th when it was a large but thin waning crescent shape. Now Venus is moving past inferior conjunction and is at a orbital position similar to the one it had in July making Venus appear at its greatest brightness.
Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.