When February opens, the evening sky remains devoid of any bright planets. However, during the last week of the month, first Venus . . . then Mercury, the two “inferior” or inner planets, emerge from the bright sunset glow very low above the western horizon about a half hour after sunset. After they set, we then must wait until Jupiter rises during the middle of the night, followed an hour or two later by Mars and finally about an hour or two after that by Saturn. Mars teams up with the so-called “rival of Mars,” the red first-magnitude star Antares, in the morning sky of Feb. 10th.
In our schedule, remember that when measuring the angular separation between two celestial objects, your clenched fist held at arm’s length measures roughly 10 degrees. Here, we present a schedule below which provides some of the best planet viewing times as well directing you as to where to look to see them.
Mercury passes superior conjunction, on the far side of the sun, on February 17, making it unobservable until the last few days of February, when it will be visible briefly after sunset, sitting very low in the western evening sky near Venus. Mercury’s return kicks off a very good evening apparition for northern hemisphere observers.
Credit: Starry Night
Mercury – cannot be seen during most of February because it reaches superior conjunction (beyond the sun) today. But as it approaches perihelion on March 10th, the planet moves rapidly into the evening sky. Setting 45 minutes after the sun by February 28th, Mercury will then shine at magnitude -1.4, as bright as the brightest star in the sky, Sirius.
In early February Venus is positioned very low in the western evening sky after sunset, so it will be difficult to discern within the surrounding sky glow. Each evening through the month, our bright sister planet will climb higher and become easier to see. In early evening on February 16, the very young crescent moon will sit 2 degrees to the upper left of Venus. Look for the pair of objects low in the western sky for a short period after sunset.
Credit: Starry Night
Venus – This brightest of planets returns to evening visibility after spending most of the past year in the morning sky. Most of us won’t get to glimpse it before late February however, and even then it will be low in bright twilight, Look for Venus 20 to 30 minutes after sunset just a few degrees above the western horizon. Binoculars will help you find it, especially if the sky is a bit hazy. Toward the end of the month, Mercury will be pushing up into view below and to the right of Venus.
Mars will spend February in the southeastern pre-dawn sky – rising shortly after 2:30 a.m. local time every morning. On February 1, Mars will sit only half a degree below Acrab, the highest of Scorpius’ three claw stars. After the first week of the month Mars will move eastward into southern Ophiuchus and towards the rich star fields of the Milky Way, passing about 5 degrees above its stellar twin, the reddish star Antares on the mornings around February 11. During the course of February, Mars will also slightly brighten (from visual magnitude 1.2 to 0.8) and its apparent disk diameter will increase in size from 5.6 to 6.7 arc-seconds as Earth’s orbital motion slowly reduces our distance from the Red Planet.
Credit: Starry Night
Mars – rises more than 4½ hours ahead of the sun. This orange-yellow world crosses over from Scorpius into Ophiuchus on the 7th, then passes a little more than 5° north of its rival, the ruddy star Antares on the 10th. At 4:30 a.m. local time on the 9th, look toward the southeast sky where you’ll see a wide crescent moon, about one-quarter of the way up from the horizon; Mars will be sitting about 4° to its lower right.
In mid-February, first-magnitude Mars is 143 million miles from the Earth, and presents a tiny disk 6-arc seconds in diameter. You’ll need at least a six-inch telescope, magnifying at least 300-power to make out any details on its disk. But this will more than quadruple to over 24 arc seconds by the by the planet’s opposition on July 27th.
Very bright Jupiter will shine in the eastern pre-dawn sky during February, slowly moving eastward through central Libra. On the mornings of February 7 and 8, the waning last quarter moon will appear about 7 degrees above and beside Jupiter respectively. At the beginning of the month, Jupiter will rise about 2 a.m. in your local time zone, and then rise closer to midnight at month’s end. Meanwhile, the planet will grow slightly brighter and larger in telescopes as Earth slowly draws closer to it ahead of this spring’s opposition.
Credit: Starry Night
Jupiter – shines brilliantly in the middle of the constellation Libra, the Scales. This giant among planets comes up in the middle of the night – just before 1:30 a.m. at the start of February, and about a quarter to midnight at month’s end. But those wanting to get a good look would do better to go out before morning twilight begins and see the giant planet’s 36 to 39 arc second wide disk positioned moderately high in the south. On the 7th at around 2:30 a.m. local time, look toward the southeast sky, where you’ll see the moon, about one-quarter of the way up from the horizon with Jupiter sitting about 4° to its lower right. Jupiter reaches western quadrature (90° west of the sun) on February 10th.
Saturn will be easily observable in the southeastern pre-dawn sky during February, appearing as a yellowish, visual magnitude 0.5 object among the stars of Sagittarius. Over the course of the month, Saturn will move from its position low in the east, and rise earlier, while it climbs away from the sun. The widely spaced chain of morning naked-eye planets – Saturn, then dimmer Mars to its upper right, and brighter Jupiter farther along the same trend, will nicely define the plane of our Solar System. On the morning of February 11, the old crescent moon will land 2 degrees above Saturn.
Credit: Starry Night
Saturn – the ringed planet, appears to the unaided eye as a bright, yellowish-white “star.” It rises in the southeast before dawn, about 40 minutes before first light early in the month and 1¾ hours before by month’s end. As dawn breaks on the 11th, low in southeast sky, you’ll see the moon, now a delicately thin crescent hovering a couple of degrees directly above Saturn. Don’t confuse Saturn with either Mars or Antares both nearly 30° to its west (upper right) in the morning twilight. The reddish star twinkles much more than either planet. Back in the late summer of 2016, as some might of you might recall, Saturn passed north of Antares. It has taken 18 months for Saturn to move this far from the red star. Of all the bright naked-eye planets Saturn travel slowest, taking about 29½ years to make a complete trip around the zodiac. How many Space.com readers remember the last time Saturn was where it is now, near the Sagittarius Teapot in the February dawn?
Joe Rao serves as an instructor and guest lecturer at New York’s Hayden Planetarium. He writes about astronomy for Natural History magazine, the Farmers’ Almanac and other publications, and he is also an on-camera meteorologist for Fios1 News in Rye Brook, NY.
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