Tonight – May 14, 2016 – the first two celestial bodies to pop out in the sky after sunset are the waxing gibbous moon and the king planet Jupiter. From mid-northern attitudes, look for the moon and Jupiter high in your southern sky. From the northern tropics, look overhead. From the Southern Hemisphere, look in your northern sky.
Jupiter is the fifth planet outward from the sun. It ranks as the fourth-brightest celestial body to light up the heavens, after the sun, moon and planet Venus. But Venus is now lost in the glare of the sun, leaving Jupiter to reign as the brightest starlike object in the May and June, 2016, nighttime sky.
As the Earth spins eastward beneath the heavens on the night of May 14, watch as the moon and Jupiter move westward across your sky. They’ll set in the west in the wee hours on the morning on May 15.
As the minutes and hours tick by tonight, the moon will be moving eastward relative to Jupiter and to the backdrop stars of the Zodiac – even as it is moving westward in Earth’s sky.
The eastward motion in front of the stars of the Zodiac comes from the moon’s orbit around Earth. Its apparent westward motion during the night is caused by Earth’s spin under the sky.
Jupiter is our solar system’s largest and most massive planet. It’d take some 11 Earths lined up side by side to match the diameter of Jupiter. But you have to square the diameter (11 x 11 = 121) to find that Jupiter’s surface area is about 121 times that of Earth. And you have to cube the diameter (11 x 11 x 11 = 1,331) to find that Jupiter’s volume exceeds Earth’s volume by over 1,300 times.
Jupiter’s four major moons – Io, Europa, Ganymede and Callisto – let astronomers compute the mass (heaviness) of Jupiter. This giant world has the mass of 318 Earths.
By the way, people have been inquiring about the triangle of bright lights in the east at early-to-mid evening. They are, in their order of brilliance, the red planet Mars and the ringed planet Saturn, plus the star Antares.
Bottom line: As darkness falls on May 14, 2016, use the moon to find the king planet Jupiter. Watch for them. Really. They’ll be a sight to see in your sky on Saturday evening.
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.