The planets in 2016: month by month, seven planets parade in and out of view.
Mercury the Quick. The innermost planet dashes back and forth from the morning to evening sky several times a year. Its evening showings--low in the afterglow of sunset--happen from late December 2015 into early January 2016, then again in April, then in late July and early August (very low), and in mid-December 2016. Mercury appears low in the east during dawn in late January and early February, in June (poorly), then in late September and early October. In a telescope Mercury is tiny, showing Moon-like phases but no markings.
Jupiter the King. Jupiter rules as the brightest "star" of evening from late February to July, blazing between Leo and Virgo.
Jupiter comes to opposition on March 8th. Opposition is when an outer planet (one that orbits farther from the Sun than Earth) stands opposite the Sun in our sky. So it rises around sunset, shines highest in the middle of the night, and sets around sunrise. This is also about when an outer planet is closest to Earth and appears largest.
Jupiter will sink away into the sunset in late summer, then reappear low in the dawn come late October.
Jupiter has four big moons, and you don't need a telescope to see them! Good binoculars, braced steadily against a post or tree (or on an image-stabilizing shoulder frame you can make from scrap wood; see SkyandTelescope.com/binoframe), will show Jupiter as a tiny white disk. Look closely to either side of it--can you make out a line of two, three, or four tiny points? All four become easy in a small telescope. Which is which? In the months when Jupiter is well placed, Sky & Telescope has a diagram identifying them at any date and time.
Jupiter itself usually shows at least two of its brownish-tan belts in a small telescope, and a larger scope reveals more detail: the iconic Great Red Spot (when it's on the side of Jupiter facing us), smaller white spots, ripples and turbulence in the edges of the belts and the bright zones between them, and sometimes trailing festoons in the bright Equatorial Zone. Jupiter's windy clouds are forever changing.
Fiery Mars (like Jupiter) shines in the dawn as 2016 opens. Mars will be in the evening sky from May through the rest of the year. Telescopic viewers can see the planet's yellow deserts with their subtle darker markings, its ever-changing white polar caps of snow and dry ice, occasional white clouds in its thin atmosphere, and once in a while, subtle patches of yellow dust storms that move from night to night.
Mars is a small world, almost always disappointingly tiny in a telescope. But this May and June bring the best Mars-watching opportunities we've had for 11 years. The planet is at opposition on May 22nd and closest to Earth on May 30th, when it will appear 18.6 arcseconds in diameter. Make the most of Mars in May and June! Its next close approach won't come until July 2018. But then it will appear 24.3 arcseconds wide, practically its biggest possible.
Bangle-Bedecked Saturn. Saturn shines before dawn in winter and early spring, then in the evening from May through October. It's at opposition on June 2nd. All year it remains in southern Ophiuchus, just north of Scorpius.
Saturn's yellowish globe is banded with subtler versions of Jupiter's belts and light zones. Saturn's rings form a fantastically thin disk, 150,000 miles wide but only about 100 feet thick. They consist of countless grains, pebbles, and boulders mostly of ice, each in its independent orbit.
And orbiting outside the rings, Saturn has more moons visible in amateur scopes than any other planet.
Titan, the largest of these, shows in almost any scope and appears distinctly orange in apertures of 4 inches and up. A 4or 6-inch scope usually shows Rhea, Dione, and fainter Tethys hovering closer around like bees. A 10- or 12-inch may add tiny Enceladus. Farther out is two-faced Iapetus. Use our Saturn's Moons Predictor at SkyandTelescope.com/satmoons.
Vivid Venus. This is a mediocre year for the brightest planet. Venus shines in the east during dawn in January, sinking lower week by week. It reappears very low in the sunset during summer, and then climbs into better view in the west during twilight in November and especially December 2016.
Even the smallest telescope shows Venus displaying its Moon-like phases, but that's about all.
The Deep Twins: Uranus and Neptune. Very different are the solar system's two outermost planets. For these, the challenge is finding them at all. Uranus, at about magnitude 5.8, is plainly visible in binoculars. Farther Neptune is harder at magnitude 7.8. They're at their best in the evening during fall: Uranus is in Pisces, Neptune is in Aquarius. Use the finder charts at SkyandTelescope.com/urnep. In a telescope they appear just a little larger and rounder than the pointlike stars.
Lonely little Pluto, no longer an official planet, is a difficult long-shot sighting even for advanced amateurs with 12-inch or larger scopes. Pluto is 14th magnitude, and it will remain low in the south in Sagittarius during summer for years to come. Observers who manage to detect it (using super-detailed charts!) can say they have seen, if not the faintest planet, the brightest Kuiper Belt object.
Planet Observing Tips
* Planets are bright but tiny. That means they demand top-quality optics, high magnification, and a steady atmosphere. Even then, no telescope shows as much as you'd really like.
To minimize the atmospheric "seeing" that always makes a high-power view shimmer and blur, follow these guidelines:
* Give your scope at least 30 minutes to cool to the surrounding temperature before expecting good high-power images. Big scopes take longer. A fan speeds the cooldown time and can help blow temperature ripples out of the air inside the tube. Store a big scope at nearly the outdoor temperature if you can.
* Keep warm buildings and pavement out from under your immediate line of sight. Greenery is best.
* Check your local seeing-quality forecast (as well as the cloud-cover forecast) up to 48 hours in advance at the handy sky-predictor site cleardarksky.com/csk.
* Try different powers. On any night, a planet has an optimum magnification depending on the seeing. Go no higher.
* Keep watching, and watching. Often the seeing changes fast, and the longer you watch the better your chance of catching an excellent moment or two. You'll also build up a better and better mental image the longer you scrutinize the planet and the more of these little moments you glimpse.
Planet Photos? They're Done by Video!
* Good images of the planets, including the ones in this magazine, all come from video cameras. That's because video lets you beat Earth's atmospheric seeing like nothing else. Here's how it works. You get a special little planetary video camera (they start surprisingly cheap). You put it in your telescope's eyepiece holder, usually with a Barlow lens to boost the image scale. You connect the camera to a computer and shoot a couple minutes of video while the image shimmers, shakes, sharpens up, and fuzzes out from moment to moment in the fickle seeing.
You then run the thousands of frames through software that selects sharp ones from the rest, registers them to align with each other, and stacks them into a single image. The result can be surprisingly detailed and very low-noise, suitable for contrast-boosting and other processing. Do everything well, and your final image may show much more on the planet than the same telescope will ever show your eye.
Alan MacRobert wishes he could see exoplanets.