Solar system showing relative size of (but not distance between) planets.

Keep tabs on our planets with Morrison Planetarium's quarterly guide to planetary activity.


The planet Mercury, image by NASA/JPL

The quarter begins with Mercury located west of the Sun and rising just before dawn, but it's already descending into the glare. As it disappears into the twilight, it passes behind the Sun on July 16 (superior conjunction), and moves to the eastern side of our star, gradually emerging into the evening sky after sunset. It reaches its greatest eastern elongation on August 27, when its angular separation is 27.3°, but the shallow angle of the ecliptic keeps Mercury low on the horizon. Swinging between Earth and the Sun, Mercury passes inferior conjunction on September 22, after which it reenters the predawn sky.

All three of the Moon's passes near Mercury this quarter occur quite close to the Sun in the sky and are visible only with great difficulty, if at all. The first two take place on the evenings of July 29 and August 28 and 29,



The planet venus, image by NASA/Caltech/JPL

The brightest planet is a "morning star" this season, visible in the east-northeast before dawn but low and gradually rising later each morning. On July 1, it's 30° from the Sun, rising 2 hours before dawn against the stars of Taurus the Bull. By August 1, its angular separation from the Sun has closed to 22°, and it rises about an hour and 45 minutes before dawn surrounded by the stars of Gemini the Twins. By September 1, it's 13° from the Sun, rising about an hour before it, and is a challenge to see in the growing twilight.

A very narrow, waning crescent Moon passes near Venus on the mornings of July 26, August 25, and—most difficult to see—September 24 and 25.



The planet Mars, image by NASA

This quarter, the Red Planet is a morning object, slowly moving eastward against the stars, starting in Pisces the Fishes, then moving through Aries the Ram and ending in Taurus the Bull. Along the way, it passes less than one and a half-degrees from Uranus on August 2 (see Highlights). Continuing on, it glides between the Pleiades star cluster and the bright star Aldebaran—the eye of Taurus—on August 30, making its closest (4.25°) approach to the Bull's eye on September 7. Even as it moves eastward against the stars, the faster westward movement of the entire sky from night to night causes Mars to rise progressively earlier through the season, rising at about 1:45 am on July 1, then at about 12:45 am on August 1, and around 11:45 pm on September 1.

The wide, waning crescent Moon is seen near the Red Planet on the mornings of July 21, August 19, and September 16 and 17.



The planet Jupiter, by NASA

On July 1, the largest of the planets rises around 1 am, just within a corner of the official boundary surrounding the non-Zodiacal constellation Cetus the Sea-Monster. It begins a retrograde loop on July 29, appearing to double back on its usual eastward motion against the stars. This is an illusion caused by Earth, which moves faster in its orbit, passing Jupiter and making it seem to move backward. This also makes Jupiter seem to change its location very little through September. Closely matching the movement of the stars, it rises about 4 minutes earlier each night, and by August 1 rises around 11 pm—roughly 2 hours earlier than it did a month before. By September 1, it rises earlier still—shortly before 9 pm. On September 26, it reaches opposition (opposite the Sun) and rises at sunset, and is visible for the entire night.

The Moon appears near Jupiter on the nights of July 19, Aug 15, and September 11.



The planet Saturn, by NASA/JPL/Saturn institute

The magnificent Ringed Planet—always a stunning target in telescopes—is an evening object all season, rising on July 1 around 11 pm (2½ hours after sunset) and on August 1 at 9 pm (38 minutes after sunset). It reaches opposition on August 14 rising at sunset, after which it rises during daylight, and by September 1 it rises around 6:45 pm (about an hour before sunset). All season, it lingers at the eastern end of Capricornus the Sea-Goat and moves less than 6° of arc the whole time—not even the width of your hand held at arm's length.

The Moon passes near Saturn on the nights of July 15, August 11, and September 7.


Sunrise & sunset table

Times are for San Francisco, California, and will vary slightly for other locations.

July 1 (PDT)
Sunrise | Solar Noon | Sunset
5:51 am | 1:13 pm | 8:35 pm 

August 1 (PDT)
Sunrise | Solar Noon | Sunset
6:13 am | 1:16 pm | 8:18 pm

September 1 (PDT) 
Sunrise | Solar Noon | Sunset
6:39 am | 1:09 pm | 7:38 pm