As the new year of 2017 kicks off, skywatchers have a fine array of planets to observe in both the evening and morning skies.

Brilliant Venus arrives at its greatest angular distance to the east of the sun on Jan. 12, climbing ever higher in the western sky and pulling closer to ocher-hued and much dimmer Mars. Both planets will be in good viewing position until mid-evening.

You can also use Mars on New Year's evening to point the way to the most distant planet, Neptune. Normally, one would need a good star chart or atlas to locate this faint, distant, bluish world. But on Jan. 1, it will be situated less than half a full moon's width from much brighter Mars, the closest pairing of any two planets in nearly three decades.

Jupiter comes above the horizon around the middle of the night and is high toward the south-southeast before sunrise. Saturn lies low in the southeast during morning twilight, and the rocky little world of Mercury is lower, near to the southeast horizon for much of the month. 

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. We present a schedule below that provides some of the best planet-viewing times and directs you where to look to see them:

Mercury stands at its greatest morning elongation from the sun (24 degrees) on Jan. 19, but the planet actually appears a little higher for midnorthern latitudes the previous week. Even at the end of January, look for a zero-magnitude Mercury low in the southeast about 45 minutes before sunup. About 45 minutes before sunrise on Jan. 25, look very low to the southeast horizon for a narrow sliver of the moon, only 36 hours from new phase. About 5 degrees to its lower left will be Mercury. Binoculars will help you pick out both objects up against the brightening dawn sky.

Venus: As seen from latitude 40 degrees north, this dazzling planet's altitude a half hour after sunset increases from 30 to 36 degrees between New Year's Day and month's end. Venus is stunning throughout January as the planet brightens from magnitude minus 4.3 to minus 4.6, remaining up for almost 4 hours after sunset.

Venus is at greatest elongation, 47 degrees from the sun, on Jan. 12. That is almost, but not precisely, when the planet appears half in the telescope. The appearance, called dichotomy, usually occurs a few days before a greatest evening elongation of the planet.

Try to observe the planet telescopically before the sky darkens, when Venus' disk won't dazzle your eye. On the evening of Jan. 2, two planets flank a slender crescent moon in the southwest sky. To the lower left of the moon is Venus, while to the moon's upper left is first-magnitude Mars. On New Year's Day, the reddish planet is 12 degrees to the east (upper left) of Venus; watch the two approach each other during January as they move rapidly against the backdrop of Aquarius and Pisces. On the evening of Jan. 31, Venus and Mars once again interact with a slender crescent moon, this time forming a striking triangle.

Earth is closest to the sun for the year at 9 a.m. EST, a distance of 91,404,322 miles (147,100,997 kilometers). Earth is 3.3 percent closer to the sun than it will be when the planet is at aphelion, next July 3.

Mars, as noted above, lies near Venus all through January. The two planets remain within 5.5 degrees of each other from Jan. 30 through Feb. 4. That is as close as they will come to each other before Mars pulls away from Venus to the east. The two planets present some interesting contrasts. Their colors are sparkling white and ochre-orange. Increasing in brilliance, Venus outshines Mars by 191 times at month's end; Mars meanwhile, has been dimming.

Telescopically, the Red Planet's waxing gibbous disk is tiny in most telescopes, and as it continues to recede from Earth, it continues to slowly shrink.

If you have never seen Neptune, the farthest planet in the solar system, you have a very good opportunity on New Year's Day using Mars point the way. You need a dark sky and either good binoculars or a telescope to glimpse bluish Neptune; it sits less than 0.2 degrees to the lower left of Mars, which is about one-third up in the southwest sky. Mars is a full seven magnitudes or 630 times brighter than Neptune. The moon is near Mars on Jan. 2 and again on the Jan. 31.

Jupiter comes up around 12:45 a.m. your local time on New Year's Day, around midnight by Jan. 15 and 11 p.m. by month's end, all the while shining with almost twice the brightness of the star Sirius. The lordly planet rises with the much dimmer star Spica located 4 degrees to the gas giant's lower right. Jan. 20 marks the first of three conjunctions in 2017 of Jupiter with Spica. The other two conjunctions come on Feb. 23 and Sept. 5.

But the best time to observe Jupiter in a telescope is still around morning twilight, when the planet is highest in the south. Soon after midnight on the morning of the 19th, low in the east-southeast sky, the moon is situated 2 to 3 degrees above and to the left of Jupiter.

Saturn, the famed ringed planet, rises 80 minutes before sunup on Jan. 1, and 100 minutes earlier by month's end. 

It's still "keeping company" with Antares, the heart of Scorpius, sitting about a dozen degrees to the left of the star. Golden Saturn is the only bright object in its area of the sky, within the constellation Ophiuchus, and is a little brighter than red Antares. But notice that Antares, being a star, has the greater talent for twinkling. On the morning of Jan. 24, look low toward the southeast about 1 1/2 hours before sunup and you'll see a thin, crescent moon, and sitting 3 degrees to its lower right will be Saturn.  

Source:
courtesy of SPACE

by Joe Rao

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