In this enchanting evening twilight over Danube river in Linz, Austria, planet Mercury shines in the fading glow of dusk. Mercury was the Roman god of commerce and the messenger of the gods. Mercury is the first planet from the sun and it’s always close to the sun in our skies. Therefore it's normally lost in the glare of the Sun, except for the dates near its longest elongation when it is briefly visible in morning or evening twilight. The foreground is a picturesque part of Linz. Astronomer and mathematician Johannes Kepler worked in this historic city for several years. In 1620 he observed a lunar eclipse from Pöstlingberg church which is visible in this picture (at right) on top of a 540-meter mountain overlooking Danube and the city.