Tonight – November 10, 2017 – you’ll have to stay up late, or get up Saturday before dawn, to see the wide waning crescent moon coupling up with Regulus, brightest star in the constellation Leo the Lion. The two luminaries will be highest up for the night around dawn Saturday.
As darkness is giving way to dawn, notice the relationship between the moon, Regulus, and a very bright object in the direction of sunrise. Venus is the brightest planet and brightest object in the sky besides the sun and moon. The lighted portion of the moon will be pointing toward it on Saturday and in the coming mornings. Plus you might glimpse a slightly fainter – but still very bright – planet below Venus. That’ll be Jupiter, which is just now emerging from the dawn after being behind the sun from Earth in late October. And a third planet, faint Mars, is up there, too. See the sky chart below.
And know that Jupiter is now edging higher in the dawn sky! Jupiter and Venus will have a spectacular conjunction on November 13.
If you live in southern Alaska, you can watch the moon occult – cover over – Regulus before dawn on November 11, 2017. At Anchorage, Alaska, for instance, Regulus will disappear behind the moon’s illuminated side at 7:07:17 a.m. local time and then reappear from behind the moon’s dark side at 7:25:18 local time.
Regulus is the only first-magnitude star to sit almost squarely on the ecliptic, which marks the path of the sun, moon and planets across our sky. In our day and age, the sun’s yearly conjunction with Regulus happens on or near August 23. That’s about two months after the June solstice, or about a month before the September equinox.
Ancient astronomers once thought the sun literally moved through the constellations of the zodiac, while the Earth remained at rest at the center of the universe. Of course, we now know that the Earth revolves around the sun, and that the sun resides at the center of our solar system. We also know that the sun’s apparent daily motion in front of the backdrop stars is really a reflection of Earth revolving around the sun.
The ecliptic is actually the Earth’s orbital plane projected onto the constellations of the zodiac.
Because the planets orbit the sun, and the moon orbits Earth, on nearly the same plane that Earth circles the sun, the moon and planets are always found on or near the ecliptic. If you’re an early bird, waking up before the sun, then use the moon, the star Regulus and the early morning planets Venus and Jupiter to help you envision the ecliptic with the mind’s-eye over the next several days.
Bottom line: See the waning crescent moon near Regulus from around midnight until dawn on November 11, 2017. Then watch over the coming mornings as the waning crescent moon sweeps near Regulus and then toward the planets Mars, Venus and Jupiter.
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.