by Geoff Chester | 21 May 2024 The Rising Flower Moon, imaged 2020 May 7 from Alexandria, Virginia with a Canon EOS Rebel SL2 DSLR The Moon dives through the southern reaches of the ecliptic this week, passing through the rising constellations of summer. Full Moon occurs on the 23rd at 9:53 am Eastern Daylight Time. May’s Full Moon is popularly called the Flower Moon owing to the explosion of blooming wildflowers at this time of the year. Native Americans called it the Budding Moon, Planting Moon, and Egg Laying Moon. Celtic tradition names it as the Grass Moon. On the evening of the 23rd Luna will rise in the southeast at around 9:00 pm EDT in Washington, very close to the bright red tinted star Antares in Scorpius. Between 9:38 and 10:06 pm the star will appear to slip behind the Moon’s bright disc near her northern limb. During the morning hours of the 26th Luna sits squarely in the middle of the “Teapot” asterism in the constellation of Sagittarius. The Moon’s waning gibbous brightens the southern horizons through the upcoming Memorial Day holiday weekend. With astronomical twilight now ending at around10:15 pm, we don’t have much time to enjoy a good dark sky. For suburban stargazers this isn’t much of a hindrance, but those of us who like to travel to darker locations have only an hour or so to enjoy the rising Milky Way before the soft light of our galaxy is washed out by Luna’s glare. However, the spring constellations are now in prime observing position as night fully descents. In the northern half of the sky the familiar seven star asterism of the Big Dipper lies on the meridian. The stars that form the Dipper’s “handle” guide your gaze to the northern hemisphere’s brightest star, Arcturus. We have discussed this star at length for much of the spring, but there are a number of interesting notes that add to its lengthy legacy. It was one of the first stars to have its distance measured using the parallax method, which yielded an estimate of about 40 light years. Light from the star was used to trigger a photoelectric circuit that officially opened the 1933 Chicago World’s Fair. This was 40 years after the 1893 World’s Columbian Exposition in Chicago; symbolically, light from the star that was emitted at the close of the 1893 fair opened the one in 1933. Today we know the distance to Arcturus to be 36.7 light years, so the fair timing wasn’t quite perfect. Follow the “Arc to Arcturus” to “speed on to Spica”. This blue-tinted star is the brightest luminary in the sprawling constellation of Virgo. Virgo represents Ceres, the ancient Roman goddess of the harvest. Virgo is the second-largest constellation in the sky and the largest of the Zodiacal star patterns. Most of its stars are fairly faint, but its second-brightest star, Porrima, is worth watching through a small telescope. It lies about 15 degrees northwest of Spica, and careful scrutiny through the telescope reveals it to be a binary star system. It is located about 38 light years away, and it has been under observation long enough for astronomers to see the two components complete a full orbit around their center of mass. Their orbital period is just under 169 years, and it is one of the few visual double stars whose apparent separation and position angle of the pair show a noticeable change from year to year. It is one of my favorite double stars in the sky; I have been looking at it long enough to have followed it through one-quarter of its orbit! The bright planets are now only visible to folks who rise well before the Sun. The first to rise is yellow-hued Saturn, which lies in the sparse star fields of Aquarius, one of the faint autumnal constellations. Saturn’s famous rings are currently tipped just three degrees toward our line of sight, so they appear as thin lines framing the planet’s disc. They will continue to close up until late June, then open to about five degrees when the planet reaches opposition in early September. They will appear edge-on in March, 2025. The only other visible planet is ruddy Mars. The red planet rises at the beginning of morning twilight, but he should be fairly easy to find about 45 minutes before sunrise, about 10 degrees above the southeastern horizon. Like Saturn, he is crossing a very sparse star field, so look for the brightest red-tinted object in this part of the sky.