Tonight – June 4, 2017 – the moon couples up with Spica, the brightest star in the constellation Virgo the Maiden. That much brighter point of light near the moon and Spica is actually the giant planet Jupiter.
No matter where you live worldwide, look first for the moon. The star closest to it on the sky’s dome will be Spica. Spica ranks as a first-magnitude star; in other words, it’s one of our sky’s brightest stars. But the glare from tonight’s waxing gibbous moon might make Spica look meek this evening. It might be easier to view the planet Saturn and the star Antares in the southeast at nightfall or early evening because they’re farther than Spica is from the moonlit glare. And it’ll be hard to miss Jupiter, the evening’s brightest planet, even though it’s fairly close to tonight’s moon.
Throughout the night, from everyplace worldwide, the moon, planets and stars will go westward across the sky. They go westward throughout the night for the same reason that the sun goes westward during the day. The Earth spins from west-to-east on its rotational axis, causing all these heavenly bodies to appear to travel from east-to-west every day. This apparent daily movement caused by the Earth’s rotation is called diurnal motion.
If you watch the moon from day to day, you can detect its true orbital motion around our planet. Over the course for the next several days, you’ll see the moon moving away Spica, and toward the the star Antares and the planet Saturn.
As always, the moon goes full circle in front of the backdrop stars of the zodiac in a little less than one calendar month.
The moon will meet up with the star Spica again on July 1, 2017.
Bottom line: The June 4, 2017 moon is near the star Spica on the sky’s dome and the moon is heading toward the red planet Mars.