The waxing crescent moon appears closer to the planet Saturn and the star Spica after sunset this Wednesday, August 3 than it did on Tuesday, August 2. As you can see on yesterday’s chart, the moon was farther west of of these starlike lights on Tuesday. The change in the moon’s position shows you how far the moon has traveled in its orbit around Earth in just one day’s time.
On the average, the moon journeys some 13 degrees eastward daily in front of the constellations of the Zodiac. For reference, the diameter of the moon equals about 1/2 degree of sky.
Tonight, the moon and Saturn both shine in front of the constellation Virgo. The moon only spends 2 to 3 days in front of any one zodiacal constellation, while Saturn, the 6th planet outward from the sun, stays in the same constellation for up to 2 to 3 years. The “fixed” star Spica, the brightest in the constellation Virgo, serves as a cosmic lighthouse, giving us a reference for measuring the motions of solar system bodies.
At present, the Earth in its orbit is moving away from Saturn and Spica. Therefore, when Saturn and Spica first come ...