Three of the five bright planets – Saturn, Jupiter and Mercury – are evening planets, at least nominally, but only Saturn is clearly visible after nightfall in October 2017. Meanwhile, Jupiter and Mercury are – for the most part this month – lost in sun’s glare. The other two bright planets – Venus and Mars – can be found in the morning sky, before sunup, through this month. Follow the links below to learn more about the planets in October 2017.
Jupiter sits in the glare of sunset. Jupiter beams as the fourth-brightest celestial body, after the sun, moon and Venus. And indeed, because it shines so brightly, you might glimpse it in early October very low in sunset direction at dusk. Shortly thereafter, though, Jupiter quickly follows the sun beneath the horizon each evening. And, day by day during October, Jupiter will sink closer and closer to the sun. From mid-northern latitudes, Jupiter sets about one hour after the sun in early October. By late October, Jupiter will set with the sun.
Jupiter stays out longer after sunset at more southerly latitudes. At temperate latitudes in the Southern Hemisphere, Jupiter sets about one and one-half hours after the sun in early October. In other words, the Southern Hemisphere has the better chance of spotting Jupiter early in the month, or before it disappears from the evening sky.
From both the Northern and Southern Hemispheres, Jupiter will disappear from the evening sky sometime in October 2017.
Click here for an almanac telling you Jupiter’s setting time in your sky.
Jupiter’s conjunction with the sun – when it is more or less directly behind the sun from Earth – comes on October 26. That event will mark Jupiter’s transition out of the evening sky and into the morning sky. Look for the king planet to reappear in the morning sky in November, 2017. At that time, a wonderful event will occur! Be sure to watch for Jupiter to join up with Venus to stage a close conjunction in the morning sky on November 13.
The sky’s brightest and second-brightest planet near each other will be amazing!
Jupiter shines in front of the constellation Virgo, near Virgo’s sole 1st-magnitude star, called Spica. Spica will also disappear from the evening sky in October but you might be able to catch this star near Venus in early November.
If you have binoculars or a telescope, it’s fairly easy to see Jupiter’s four major moons, which look like pinpricks of light all on or near the same plane. They are often called the Galilean moons to honor Galileo, who discovered these great Jovian moons in 1610. In their order from Jupiter, these moons are Io, Europa, Ganymede and Callisto.
These moons orbit Jupiter around the Jovian equator. In cycles of six years, we view Jupiter’s equator edge-on. So, in 2015, we were able to view a number of mutual events involving Jupiter’s moons, through high-powered telescopes. Starting in late 2016, Jupiter’s axis began tilting enough toward the sun and Earth so that the farthest of these four moons, Callisto, has not been passing in front of Jupiter or behind Jupiter, as seen from our vantage point. This will continue for a period of about three years, during which time Callisto is perpetually visible to those with telescopes, alternately swinging above and below Jupiter as seen from Earth.
Saturn out from dusk until mid-evening. On these October evenings, look for Saturn as soon as darkness falls. It’s in the southwest sky at dusk or nightfall as seen from Earth’s Northern Hemisphere, and in the west at early evening as viewed from the Southern Hemisphere. Your best view of Saturn, from either the Northern or Southern Hemisphere, is around nightfall because that’s when Saturn is highest up for the night.
From mid-northern latitudes (US and Europe), Saturn sets about two hours after nightfall in early October, and about one hour after nightfall by the month’s end.
From temperate latitudes in the Southern Hemisphere (South Africa, southern Australia), Saturn sets around midnight in early October. By the month’s end, Saturn sets some two hours earlier, around 10 p.m. local time.
Although Saturn has dimmed slightly since September, this world will still be shining at first-magnitude brightness all through October.
Be sure to let the moon guide you to Saturn (and the nearby star Antares) for several days, centered on or near October 23.
Saturn, the farthest world that you can easily view with the eye alone, appears golden in color. It shines with a steady light.
Binoculars don’t reveal Saturn’s gorgeous rings, by the way, although binoculars will enhance Saturn’s color. To see the rings, you need a small telescope. A telescope will also reveal one or more of Saturn’s many moons, most notably Titan.
Saturn’s rings are inclined at 27o from edge-on, exhibiting their northern face. In October 2017, the rings open most widely for this year, displaying a maximum inclination.
As with so much in space (and on Earth), the appearance of Saturn’s rings from Earth is cyclical. In the year 2025, the rings will appear edge-on as seen from Earth. After that, we’ll begin to see the south side of Saturn’s rings, to increase to a maximum inclination of 27o by May 2032.
Click here for recommended almanacs; they can help you know when the planets rise, transit and set in your sky.
Venus, brilliant in east at morning dawn Venus is always brilliant and beautiful, the brightest celestial body to light up our sky besides the sun and moon. If you’re an early bird, you can count on Venus to be your morning companion all month long.
Although Venus will remain in the morning sky for the rest of this year, Venus will sink closer and closer to the glare of sunrise over the next few months. October will present Venus higher up and easier to view in the morning sky than will the months of November and December of 2017.
Watch out for these highlights. Venus and Mars will have a spectacular conjunction in the morning sky on October 5. Then, later in the month, enjoy the picturesque display of the waning crescent moon and Venus plus Mars) for several mornings, centered on October 16.
Venus reached a milestone as the morning “star” when it swung out to its greatest elongation from the sun on June 3, 2017. At this juncture, Venus was farthest from the sun on our sky’s dome, and the telescope showed Venus as half-illuminated in sunshine, like a first quarter moon. For the rest of the year, Venus will wax toward full phase.
Click here to know Venus’s present phase, remembering to select Venus as your object of interest.
From mid-northern latitudes (U.S. and Europe), Venus rises about two hours before the sun in early October, and about one and one-half hours before sunrise by the month’s end.
At temperate latitudes in the Southern Hemisphere (Australia and South Africa), Venus rises about one hour before sunup in early October. By the month’s end, that’ll taper to about 40 minutes.
Click here for an almanac giving rising times of Venus in your sky.
The chart below helps to illustrate why we sometimes see Venus in the evening, and sometimes before dawn.
Mars climbs out of the glare of sunrise. Mars transitioned out of the evening sky and into the morning sky on July 27, 2017, at which juncture Mars was on the far side of the sun at what astronomers call superior conjunction.
Look for Mars to emerge in the east before dawn in late September or early October 2017. The conjunction of Mars and Venus on October 5, 2017, will likely present the first view of Mars in the morning sky for many sky watchers. Be sure to watch the moon pass close to Mars on the morning of October 17.
Exactly one year after Mars’s superior conjunction on July 27, 2017, Mars will swing to opposition on July 27, 2018. This will be Mars’s best opposition since the historically close opposition on August 28, 2003. In fact, Mars will become the fourth-brightest heavenly body to light up the sky in July 2018, after the sun, moon and the planet Venus. It’s not often that Mars outshines Jupiter, normally the fourth-brightest celestial object.
Mercury lost in the glare of sunset. Mercury will transition out of the morning sky and into the evening sky on October 8. But Mercury may not climb high enough above the glare of sunset to become visible in the evening sky until November 2017.
Mercury is tricky, even when it becomes visible. If you look too early, Mercury will still be obscured by evening twilight; if you look too late, it will have followed the sun beneath the horizon.
The Southern Hemisphere has the advantage and could possibly catch Mercury by the end of October. Watch for Mercury low in the sky, and near the sunset point on the horizon, being mindful of Mercury’s setting time.
What do we mean by bright planet? By bright planet, we mean any solar system planet that is easily visible without an optical aid and that has been watched by our ancestors since time immemorial. In their outward order from the sun, the five bright planets are Mercury, Venus, Mars, Jupiter and Saturn. These planets actually do appear bright in our sky. They are typically as bright as – or brighter than – the brightest stars. Plus, these relatively nearby worlds tend to shine with a steadier light than the distant, twinkling stars. You can spot them, and come to know them as faithful friends, if you try.
Bottom line: In October 2017, Three of the five bright planets – Saturn, Jupiter and Mercury – are evening planets, at least nominally, but only Saturn is clearly visible after nightfall. Two other bright planets – Venus and Mars – can be found in the morning sky, before sunup.
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.