On or around July 9, 2018, view the dazzling planet Venus near Regulus, the brightest star in the constellation Leo the Lion. Their conjunction is July 9 around 20 UTC, when Venus will be 1.1 degree north of Regulus on the sky’s dome. As seen from around the world around that date, just look westward at dusk. You can’t miss Venus, the third-brightest celestial body to light up the sky after the sun and moon. Then, as dusk gives way to nightfall, watch for Regulus to pop out next to Venus. If you aim binoculars at Venus, you’ll be able to see Regulus all the sooner after sunset, as the two will easily fit inside the same binocular field of view.
Conjunction means two heavenly bodies appear north and south of each other on the imaginary grid of stars surrounding Earth. At such times, you can expect to see these two bodies near each other in the sky. At this particular conjunction, Venus sweeps about one degree (two moon-diameters) north of Regulus on the sky’s dome. Although the gap between Venus and Regulus will widen after July 9, they’ll be close enough to occupy a single binocular field for several more days.
Watch for Venus to climb upward, away from Regulus, in the days following July 9.
Although Regulus ranks as a 1st-magnitude star, it pales next to Venus. Venus, the brightest of all planets, beams nearly 150 times more brilliantly than Regulus, the only 1st-magnitude star to sit almost squarely on the ecliptic. The ecliptic is a projection of the Earth’s orbital plane onto the celestial sphere.
In addition, the ecliptic depicts the annual pathway of the sun in front of the constellations of the zodiac. The sun passes in front of the constellation Leo each year from around August 10 to September 17, and has its yearly conjunction with the star Regulus on or near August 23.
The star Regulus is often used to catalog the motions of the planets in front of the backdrop stars. Eight years from now – on July 9, 2026 – look for Venus to return to virtually the same spot upon the stellar sphere, again passing to the north of Regulus in the evening sky. Moreover, the telescope will show Venus’ disk exhibiting a similar waning gibbous phase (aproximately 66 percent illuminated).
Relative to the backdrop stars of the zodiac, Venus goes around the sun 13 times for every time that the Earth circles the sun eight times, accounting for Venus’ famous eight-year cycle.
Bottom line: On July 9, 2018 – or on the evenings around then – as darkness falls, let the brilliant planet Venus act as your guide to Regulus, the constellation Leo’s brightest star.
Bruce McClure has served as lead writer for EarthSky's popular Tonight pages since 2004. He's a sundial aficionado, whose love for the heavens has taken him to Lake Titicaca in Bolivia and sailing in the North Atlantic, where he earned his celestial navigation certificate through the School of Ocean Sailing and Navigation. He also writes and hosts public astronomy programs and planetarium programs in and around his home in upstate New York.