On the Jan. 1, Venus will sit to the lower left of the moon; on Jan. 3, Jupiter will be stationed to the right of a noticeably thinner lunar crescent, while on Jan. 4, a hairline crescent will be sitting above and slightly to the left of Mercury. Later in the month, Saturn emerges from the glare of the rising sun, replacing Mercury. Venus and Jupiter mimic a "double planet" when engage in a spectacular conjunction on Jan. 22 and finally at month's end, these two brilliant planets are again joined by the crescent moon, while the brightest luminary in the constellation Scorpius, the bright red star Antares sits off to the right of this eye-catching gathering.
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 — starts January in the morning sky, about an hour before sunrise and just above the east-southeast horizon. This innermost planet to the sun shines at magnitude -0.5 some 12 degrees to the lower left of Jupiter. A week later it will rise only ¾ hour before sunup, becoming quite difficult to see. It arrives at superior conjunction on Jan. 29, sweeping around behind the sun and entering the evening.
Venus — is a magnificent sight before and during dawn. On the first morning of the New Year, observers around 40-degrees north latitude can watch Venus rise a rare 3.75 hours before the sun, and climb to 20 degrees above the southeastern horizon while the sky is still fully dark. And as a bonus on this same day, hovering a half dozen degrees to its upper right will be a lovely crescent moon.
Also this morning, take note of Jupiter about 18 degrees to the lower left of Venus. They will get a bit closer to each other each morning and will have an eye-catching conjunction with each other on Jan. 22.
Venus is at greatest western elongation from sun (47 degrees) on Jan. 6. On which morning around this time will Venus look most precisely half-lit in your telescope? You'll get the best views as Venus climbs higher in the brightening sky just before sunrise — or even after.
Unfortunately for observers at mid-northern latitudes, Venus is quite far south this month (passing north of Scorpius) and therefore not as high as it usually is when near greatest elongation. Nevertheless, this dazzling planet has a beautiful accompaniment of stars — and planets later in the month (see Jupiter).
Earth — will be closest to the sun for the year at 12 a.m. EST on Jan. 3; a distance of 91,403,553 miles (147,099,760 km). We are 3.3 percent closer to the sun than we will be when the Earth is at aphelion July 4.
Mars — continues to fade all month, dimming from magnitude +0.5 to +0.9 as its distance from Earth increases from 10.6 to 12.7 light minutes. Several days earlier (on Jan. 8) it's aligned with the stars on the east side of the Great Square of Pegasus.
Mars is also edging toward the western evening twilight, but with its rapid motion eastward against the stars, Mars almost overcomes the seasonal westward turning of the celestial sphere. Its setting time of around 11:10 p.m., changes by less than 10 minutes all month. Mars will be hanging in our evening sky through the first half of 2019 as more than several zodiacal constellations slide to the west behind it. On the evening of Jan. 12, as darkness falls, look about halfway up in the south-southwest sky for a wide waxing crescent moon and hovering well above and to its right will be the red planet.
Jupiter — starts the year shining at magnitude -1.8. More interestingly for naked-eye observers, this cream-colored world spends January well to the left of dimmer, ruddy Antares.
Early on the morning of Jan. 3, about an hour before sunrise, look low toward the southeast horizon for a view of a narrow sliver of a crescent moon sitting about 3 degrees to the left of Jupiter. Even by month's end, however, Jupiter's southerly declination keeps it quite low in the southeast.
On the morning of Jan. 22, Jupiter teams with Venus in a spectacular conjunction, drawing all eyes to the southeastern sky before and during dawn. Early in January Jupiter shines to Venus's lower left, closing in on it day by day. They have a spectacular conjunction this morning, shining just 2.4 degrees apart.
Thereafter, Jupiter moves off to Venus' upper right. Venus appears a full 10 times brighter than the king of the planets. Well off to their right is ruddy Antares, one of the brightest stars in the sky and yet it shines only 1/15 as bright as Jupiter and 1/150 as bright as Venus.
Finally, on the final day of the month, an already beautiful array of Venus, Jupiter and Antares is augmented in the morning sky by the presence of a lovely crescent moon, positioned between Venus and Jupiter. Venus will be about 2.5 degrees to the lower left of the moon, while is Jupiter is twice that distance to the moon's upper right. Antares will be far to the right of the trio.
Saturn — is in conjunction with the sun on Jan. 2. Beginning the third week of January, use binoculars, and scan just above the east-southeast horizon about 45 minutes before sunrise. Piercing through the glare of dawn will be Saturn; it will appear a bit higher every morning thereafter. You can then look for it far down to the lower left of Venus, Jupiter and Antares; it's the only bright object in its area of the sky, the constellation Sagittarius.
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 Verizon FiOS1 News in New York's Lower Hudson Valley.
