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This is the Griffith Observatory Sky Report through June 10, 2015. Here’s what’s happening in the skies of southern California.
The brightest planet, Venus, and the second brightest planet, Jupiter, are spectacular in the western sky after sunset. Between the 3rd and 10th, the angular distance between Jupiter and Venus shrinks from 18½ degrees to 13 degrees. The climax of this slow approach will come when the two planets are only 1/3 degree from each other at the end of the month. Venus sets in the west-northwest at about 11:15 p.m. Jupiter follows Venus below the horizon less than an hour later.
Venus appears at its greatest angular distance from the sun on the 6th, when it is 45.4 degrees east of the sun. This is called the greatest elongation of Venus. Through a telescope, the apparent size of Venus grows from 23 to 25 arcseconds between the 3rd and the 10th. The illuminated portion of the planet’s disk drops from 51 percent to 47 percent, and is exactly half-illuminated on the 6th.
Jupiter’s oval storm, the Great Red Spot, will be visible through telescopes to observers in California on Wednesday the 3rd, Friday the 5th, and Monday the 8th. Several passages of shadows of Jupiter’s Galilean moons across the disk of Jupiter (shadow transits) occur over the next few evenings. On Wednesday the 3rd, the shadow of the moon Io begins its transit at 8:56 p.m. followed by the transit of the moon Ganymede at 9:58 p.m. The shadow of Jupiter’s moon Callisto will begin its transit at 8:21 p.m. on the 6th.
The ringed planet, Saturn, in Libra the Scales, is low in the sky toward the east-southeast during evening twilight. Saturn is highest, in the south, at 11:40 p.m. and sets in the west-southwest at dawn. A telescope is needed to see the north face of Saturn’s ring system, now tilted 25 degrees from edge-on to us. Venus, Jupiter, and Saturn are all featured objects through the public telescopes at Griffith Observatory.
The time of moonrise advances from 9:05 p.m. on the 3rd to 1:33 a.m. on the 10th. The moon’s phase is gibbous through the morning of the 8th, is last quarter on the 9th, and is crescent on the mornings before the 16th when the moon is new.
Free views of the sun during the day and of the moon, planets, and other celestial objects at night are available to the public in clear weather through Griffith Observatory’s telescopes from Tuesday through Sunday before 9:30 p.m. Check our website for the schedule. The next public star party on the grounds of Griffith Observatory, hosted by the Los Angeles Astronomical Society, the Sidewalk Astronomers, and the Planetary Society, will take place on Saturday, June 20.
Follow the Sky Report on Twitter for updates of astronomy and space-related events.
From Griffith Observatory, I’m Anthony Cook and I can be reached at griffithobserver@gmail.com