Four of the five bright planets – Mercury, Mars, Jupiter and Saturn – reside exclusively in the morning sky, before sunup, in January 2018. Mars and Jupiter are easy in the sunrise direction before sunup. They’re bright and in conjunction on January 7. Mercury is best seen in the first half of the month; Saturn is better viewed in the second half. Near mid-month, watch for Mercury and Saturn to meet up for their conjunction as the predawn darkness gives way to dawn. The brightest planet, Venus, is lost in the sun’s glare all month long, as it transitions from the morning to evening sky. Follow the links below to learn more about the planets in January 2018.
Venus transitions from morning to evening sky Venus ranks as the third-brightest celestial body to light up our sky, after the sun and moon. Even so, this planet will be out of view as it moves from the morning to evening sky in January 2018.
You might have to wait until February or March 2018 to catch Venus in the west after sunset. In February 2018, Venus will set only a short while after the sun.
Did you see the spectacular conjunction of Venus and Jupiter in the morning sky on or around November 13, 2017? If not, check out these photos. Since the conjunction, Jupiter has been climbing away from the glare of sunrise day by day while Venus has been falling toward the sunrise daily. Throughout January 2018, Venus remains totally lost is the sun’s glare.
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 a 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.
Why a half Venus? Why a full Venus? It’s all about the angle at which we see Venus with respect to the sun. When we view Venus to one side of the sun – as we did when it was at its greatest elongation in June – then we see it as half illuminated. That is, we’re seeing half of Venus’ lighted half (a quarter Venus). Now, Venus is nearly behind the sun from Earth. We’re seeing more of its dayside: a nearly full Venus.
Click here to know Venus’s exact phase at present, remembering to select Venus as your object of interest.
The chart below helps to illustrate why we sometimes see Venus in the evening, and sometimes before dawn.
Jupiter lights up predawn/dawn sky. Because Venus is lost in the sun’s glare this month, the king planet Jupiter takes over as the brightest starlike object to adorn the nighttime sky. Jupiter beams during the predawn hours all month long.
This month, Jupiter shines in front of the constellation Libra the Scales and close to Libra’s alpha star, Zubenelgenubi. Use brilliant Jupiter to locate Zubenelgenubi, and then use binoculars to view this star as a double star!
Before dawn, look for modesty-bright Mars right above Jupiter in the first week of January. Then watch the gap between Jupiter and the red planet Mars rapidly come to a close. These two worlds will meet up in front of the constellation Libra for a stunningly close conjunction in the morning sky on January 7, 2018. After their conjunction, Jupiter will climb upward away from Mars.
Be sure to watch for the waning crescent moon near Jupiter (and Mars) for several mornings, centered on January 11.
From mid-northern latitudes, Jupiter rises about 4 hours before the sun (approximately 3 a.m. local time) in early January. By the month’s end, Jupiter comes up at around 2 a.m. local time.
From temperate latitudes in the Southern Hemisphere, Jupiter rises around 2 a.m. local time in early January; and by the month’s end, Jupiter rises around midnight.
Click here for an almanac telling you Jupiter’s rising time in your sky.
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.
Mars near Jupiter in predawn sky. Look for Mars (and Jupiter) to rise in the east several hours before the first stirrings of morning twilight. Mars and Jupiter are the only naked-eye planets to grace the predawn sky all month long (although Mercury and Saturn play peekaboo at and around dawn). Mars starts out the month about 3o above the king planet Jupiter. (For reference, one finger-width at an arm length spans about 2o of sky.) The gap between Mars and Jupiter will quickly close as the two worlds meet up for a conjunction on January 7, 2018.
It’s best to look for Mars before dawn (approximately one and one-half hours before sunrise) because this ruddy gem is only modestly bright right now. Mars is nowhere as brilliant as Jupiter, which outshines Mars by about 20 times in early January. Jupiter is even visible in a twilight sky.
Be sure to let the waning crescent moon help guide your eye to Mars (and Jupiter) for several mornings, centered on January 11.
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 its 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 body.
Saturn climbs out of the sunrise glare. Saturn transitioned out of the evening sky and into the morning sky on the December solstice, and might not be seen in the morning sky until the Mercury and Saturn conjunction on January 13, 2018.
Saturn, the farthest world that you can easily view with the eye alone, appears golden in color. It shines with a steady light. Let the waning crescent moon help guide your eye to Saturn (and Mercury) for several mornings, starting around January 12.
From mid-northern latitudes (US and Europe), Saturn rises about 45 minutes before sunrise in early January. By the month’s end, look for Saturn to rise better than two hours before the sun.
From temperate latitudes in the Southern Hemisphere (South Africa, southern Australia), Saturn rises about 45 minutes before sunrise in early January; and by the month’s end, the ringed planet comes up nearly 3 hours before the sun.
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 now inclined at about 26o from edge-on, exhibiting their northern face. In 2017, the north side of the rings opened up most widely (27o) since since the last grand opening in 1988. The next maximum exposure of the north side of Saturn’s rings will take place in 2046.
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.
Mercury before sunrise in early January. Mercury will be in the morning sky all month long. But it will be sinking toward the sunrise day by day, so the first half of the month is more opportune for seeing the solar system’s innermost planet. Be sure to watch the conjunction of Mercury and Saturn on January 13, 2018.
After their conjunction, Mercury will sink toward the sunrise whereas Saturn will climb away from the glare of morning twilight. By February, Saturn will be easy to see in the predawn sky, whereas Mercury will have disappeared from view.
At mid-northern latitudes – such as in the United States and Europe – Mercury will rise about 100 minutes before the sun in early January. By the month’s end, that’ll taper to about 30 minutes before sunrise.
At temperate latitudes in the Southern Hemisphere – South Africa, southern Australia and New Zealand – Mercury rises about 90 minutes before the sun in early January; and by the month’s end, will rise about one hour before the sun.
Mercury is tricky, even when it becomes visible. If you look too early, Mercury will still be under the horizon; if you look too late, it will be obscured by morning twilight. Watch for Mercury low in the sky, and near the sunrise point on the horizon, being mindful of Mercury’s rising time.
Use the lit part of the waning crescent moon to find Mercury pairing up with Saturn on the mornings of January 12, 13 and 14. (See above sky chart.)
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 January 2018, four of the five bright planets – Mercury, Mars, Jupiter and Saturn – are up before dawn. Mars and Jupiter have a close conjunction on January 7. Mercury and Saturn stage their conjunction on January 13. Venus is lost in the sun’s glare all month.
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.