Tonight – June 30, 2017 – be sure to watch the magnificent pairing of the moon and Jupiter as darkness falls. The moon and Jupiter rank as the brightest and third-brightest heavenly bodies of nighttime. What’s the second-brightest? It’s the blazing planet Venus, which resides exclusively in the morning sky for the rest of 2017.
Also, look for a bright star near Jupiter and the moon. This star is Spica – near Jupiter throughout 2017 – brightest light in the constellation Virgo.
The moon reaches its first quarter phase on July 1, 2017 at 0:51 UTC. Converting Universal Time to the clock time at North American time zones, the moon’s first quarter phase happens on June 30, at 9:51 p.m ADT, 8:51 p.m. EDT, 7:51 p.m. CDT, 6:51 p.m. MDT 5:51 p.m. PDT and 4:51 p.m. AKDT.
At quarter moon, the moon’s disk is half-illuminated by sunlight and half-immersed in the moon’s own shadow. The lunar terminator – the shadow line crossing between the moon’s day and night sides – shows you where it’s sunrise on the waxing first quarter moon. The moon is said to be at first quarter because, in its cycle of phases, the moon is one quarter the way from one new moon to the next.
Jupiter ended its retrograde motion earlier this month (June 10), which means the best time of 2017 for viewing this dazzling planet has ended.
Thus Jupiter is now moving eastward along the ecliptic again – going toward Spica, Virgo’s brightest star. Keep watching as Jupiter moves toward Spica, to pass 3o north of this star on September 5, 2017.
Because Jupiter is roughly in the same area of sky as the moon this evening, you might expect this world to exhibit a similar phase to tonight’s moon. Not so. Jupiter is so far distant from Earth that it always appears nearly 100% illuminated from our earthly perspective.
Bottom line: The dazzling planet Jupiter is near the first quarter moon on June 30. Enjoy the waxing moon and Jupiter on July 1, too!
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.