The chart above displays the setting time of Venus (green curve) compared to sunset. The three phases of twilight are displayed as well. The setting time differences are displayed for bright stars near the ecliptic as well as other bright planets. The moonset interval is displayed with circles. The rising time difference – compared to sunset – is displayed for Jupiter and Saturn as well. When the planets rise at sunset, they are at opposition.
Venus as an Evening Star, semi-technical summary.
Saturn’s opposition with Venus is displayed as a brown box on the Saturn Rising line. A yellow box on the Jupiter Rising line indicates a similar event, Venus – Jupiter opposition. In the evening, when two planets are at opposition, opposite sides of Earth, one is rising as the other sets. A week or so after these dates Saturn, then Jupiter, appear in the eastern sky as Venus shines from the west. In this study of Venus, this trio is in the sky together during evening hours until nearly the end of its evening appearance during early 2022.
When the Venus curve crosses another line, Venus and that celestial object set at the same time. Conjunctions occur near this date. White boxes on the charts indicate conjunctions with stars and other planets. The yellow triangle, with the letters “GE,” indicates the greatest elongation dates of Venus and Mercury.
The setting chart is from data by the U.S. Naval Observatory’s Multiyear Interactive Computer Almanac (MICA) for Chicago, Illinois. Make any appropriate adjustments for different latitudes. Time intervals after sunset are used in the following notes for observers to determine the appropriate observing clock time at their locations.
April 25, 2021: Mercury passes Evening Star Venus this evening after sunset. Look low in the western sky about 20 minutes after sunset. Mars is marching eastward in Gemini, near the star cluster Messier 35. The bright moon is near Spica.
April 25, 2021: Morning planets Jupiter and Saturn are in the southeast before sunrise. Jupiter is in front of the stars of Aquarius, while Saturn’s starry background is Capricornus.
April 24, 2021: Brilliant Evening Star Venus and bright Mercury are entering the evening sky. They are low in the west-northwest during evening twilight. The bright moon is in the southeast in Virgo. Mars moves into Gemini as it approaches the star cluster Messier 35.
April 24, 2021: The bright gibbous moon is near a star in Virgo during the early morning. From parts of the Western Hemisphere, the moon covers the star. Before sunrise, bright morning planets, Jupiter and Saturn are in the southeast before sunrise.
April 23, 2021: Evening Star Venus and Mercury are entering the evening sky. They are found very low in the west-northwest after sunset. The bright moon is in the southeastern sky during the early evening. Mars is moving toward the star cluster Messier 35.