Though Venus was at its greatest eastern elongation (angle from the Sun) back on June 6, and has since then been falling gradually toward the Sun and lower in the evening sky, it has also been getting slightly brighter. Its little shape in the telescope, growing slenderer but longer as it curves in between us and the Sun, shows largest in area (the “greatest illuminated extent,” explained earlier) on July 10. And today, July 12, its total brightness reaches a soft peak.
Venus is now about 10 degrees lower in the sunset sky than it was on June 6. Its sunward fall is picking up speed. A clearer (or not?) way of expressing this might be that its failure to keep ahead of the Sun is growing.
On July 15 it will show at a minimum distance (2.4 degrees) from Regulus – an “appulse” – but because of its curving-back path in the sky it will never quite reach a position due south of the star, that is, have a “conjunction in right ascension” with it.
Ah, this is one of my most favorite times to be keeping my eye on Venus. Even with just binoculars, one can see the crescent becoming thinner and thinner til…… well,,, how close to the sun dare you look at something with any magnification? Safety first!
I greatly enjoy showing passersby (de)crescent Venus in mounted binoculars, explaining the orbits of Venus and Earth around the Sun, and telling the story of Galileo’s telescopic observation of Venus and his conclusion that Copernicus was right (and, perhaps more importantly to Galileo, that Ptolemy and Aristotle were wrong! ). People are surprised that you can see a planet in a bright blue sky, and those with sharper eyes are pleased to find Venus for themselves.
On Friday a fellow who works at the auto repair shop across the broad avenue from my home crossed the street to ask me what I was looking at. I showed him Venus and told him he would be able to see Venus and Jupiter easily when the sky started to get dark. He planned to go home and show his nine year old daughter these planets after dinner.