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

Being closest to the Sun, Mercury has the shortest orbital period, so its fast-changing motions are easiest to see among the planets. On October 1, it's located in the evening sky at greatest eastern elongation (greatest angular separation east of the Sun), but the shallow angle of the ecliptic (the plane of the solar system) with respect to the horizon keeps it low and hidden by the Sun's glare. Retreating back into the glow, it passes inferior conjunction on October 25 and doesn't return to our view until early November, when it rises in the east before dawn. This time, the angle of the ecliptic is very steep, making Mercury easier to see.

Reaching its greatest western elongation on November 10, the swift, little world darts back into the glow by the end of the month. It passes behind the Sun and reaches superior conjunction on December 19 and returns to the evening sky, setting in the west after the Sun in early January.

The season's only visible encounter between Mercury and the Moon is on the morning of November 13, when both rise about two hours before dawn. When the Moon passes near Mercury on October 17 and December 14, they're both hidden in the glare of the Sun.



The planet venus, image by NASA/Caltech/JPL

"Earth's twin" remains a predawn object for the rest of the year, passing from the stars of Leo the Lion through Virgo the Maiden, Libra the Scales, Scorpius the Scorpion, and Ophiuchus the Serpent-Bearer. On the morning of October 2, it can be seen only a half-degree (one full Moon diameter) from the star Regulus, which represents the heart of Leo. As it slowly moves to the far side of its orbit from Earth, we see it in telescopes as a waxing gibbous. At the same time, as its distance increases, it appears to shrink in size.

The waning crescent Moon passes near Venus on the mornings of October 13 and 14, November 12, and December 12.



The planet Mars, image by NASA

At the beginning of October, the Red Planet is already in the sky at nightfall, rising in the east against the stars of Pisces the Fishes. It reaches opposition on October 13 (details in Highlights), then gradually rises about five minutes earlier each night, gradually being seen higher and becoming more prominent in the southeast when seen at the same time after sunset in November and December.

The Moon passes near Mars on the evenings of October 2, October 29, November 25, and December 23.



The planet Jupiter, by NASA

The two largest naked-eye planets are so close together that practically everything pertaining to observation of one also applies to the other. At the beginning of October, Jupiter and Saturn are due-south at nightfall, located against the stars of Sagittarius the Archer and about seven degrees from each other (about the width of the field of view in a pair of binoculars). In early November, they're low in the south-southwest at nightfall, separated by five degrees, and by December 1, they've moved to the southwest, less than three degrees apart. Notice that they're moving closer, and on the evening of December 21, they'll be very low in the southwest and across the border from Sagittarius into Capricornus the Sea-Goat. On that date, they're at their closest-together, as described in Highlights.

The Moon joins Jupiter (and Saturn), forming a compact cluster with them on the evenings of October 22, November 18, and (as a very thin, waxing crescent) December 16.



The planet Saturn, by NASA/JPL/Saturn institute

As noted above, Saturn is creeping ever-closer to brighter Jupiter this season, culminating with their super-close encounter on December 21 (detailed in Highlights). Saturn is fainter than Jupiter because it's slightly smaller and about twice as distant (nearly a billion miles away). It is, however, unique for its magnificent ring-system, which is easily visible through medium-size telescopes.

The Moon passes near Saturn at the same time as its close encounter with Jupiter on October 22, but is east of the pair and a little closer to Saturn on November 19. On December 16, Jupiter and Saturn are so close together that the Moon passes both at the same time.


Sunrise & Sunset Table

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

October 1 (PDT)
Sunrise | Solar Noon | Sunset
7:05 am | 12:59 pm | 6:52 pm 

November 1 (PST) 
Sunrise | Solar Noon | Sunset
6:35 am | 11:53 am | 5:10 pm

December 1 (PST)
Sunrise | Solar Noon | Sunset
7:06 am | 11:58 am | 4:51 pm