Happy hunting! The start of 2015 brings a new year of planet hunting for amateur astronomers around the world, and plenty of dazzling views of the planets await in January for the stargazer who knows where and when to look. Brilliant Venus will readily guide observers to Mercury in the January night sky. At magnitude minus 0.8 on New Years Day, Mercury should be easily visible 3 degrees to the lower right of Venus and sets one hour after the sun. (Your closed fist held out at arms length covers about 10 degrees of the night sky). By Jan. 10, this interval will have become 90 minutes, with Mercury and Venus separated by less than two-thirds of a degree. But this months Venus-Mercury pairing is not mentioned in the list of planetary configurations in the US Naval Observatory;s Astronomical Almanac or the Royal Astronomical Society of Canadas Observers Handbook. Both include all conjunctions of planets that occur at least 10 degrees from the sun. (As defined in these publications, a conjunction occurs when two objects have the same right ascension in the sky.) [Best Night Sky Events in January 2015 (Sky Maps)] Mercury Comes Close to Venus in January 2015Pin It Look to the skies during January to see a number of awesome celestial events. Venus will be particularly impressive this month, and Mercury will be easy to spot in evening twilight. Credit: Starry Night softwareView full size image As noted below, when two bright planets come within 5 degrees without an actual conjunction in right ascension the event is called a quasi-conjunction. The last such happening was an eye-catching Venus-Jupiter pairing in the morning sky in July 2012. According to Jean Meeus the next two quasi-conjunctions will occur in 2016: Mercury and Venus, least separation 4 degrees on Feb. 13; Mercury and Jupiter, 3.8 degrees on Aug. 20. But this months event easily tops those two in observational interest. For 10 dates (Jan. 6-15) Mercury and Venus will be separated by less than 2 degrees, and for five of those nights (Jan. 8-12) the two planets will be less than 1 degrees apart. [Related: Must-See Night Sky Events of 2015] Below, we present a schedule that provides some of the best planet-viewing times as well as where to look to see them: Jan. 4: Earth is at perihelion. It is closest to the sun for the year at 2 a.m. EST, at a distance of 91,401,343 miles (147,096,202 kilometers). On this date, Earth is 3.3 percent closer to the sun than it will be when at aphelion, next July 6. Jan. 7: This evening, look low toward the east-northeast horizon around 8 p.m. for the waning gibbous moon and about 6 degrees to its left youll see Jupiter. Now nearing its Feb. 6 opposition, the solar system’s biggest planet rises in early evening during January — about 90 minutes after twilights end on New Years Day, and in bright twilight by late in the month. Jupiter is big and bright, blazing at magnitude minus 2.5 and not far from the Sickle of Leo. Its high enough for superb telescopic views by late evening, but many details may already be visible on its busy face before then. Jan. 10: The well-known astronomer Jean Meeus of Belgium defines a quasi-conjunction as an approach of two bright planets within 5 degrees of each other, without an actual conjunction in right ascension. Such will be the case between Venus and Mercury. During the first 19 days of January these two planets will be less than 5 degrees from each other. On New Years Day, Mercury will be positioned 3 degrees below and to the right of Venus. In the days that follow, it will appear to slowly creep up toward Venus. They will appear closest together this evening, separated by just 0.65 degrees. Mercury will be shining at a very bright magnitude of minus 0.8; among the stars only Sirius is brighter. And yet, dazzling Venus outshines Mercury by more than 17 fold. The two planets will then gradually separate in the nights that follow, with Mercury slowly moving away to Venuss right. Jan. 14: Mercury reaches greatest elongation, 19 degrees east of the sun. Still shining at a very bright magnitude of minus 0.6, the planet will fade rapidly in the days ahead and is not likely to be seen after the Jan. 23. Inferior conjunction occurs on the Jan. 30. Jan. 19: Mars will provide a great opportunity for you to sight the outermost planet, Neptune. This evening the red planet will pass just 0.2 degrees to the south of bluish Neptune. Good binoculars or a small telescope should be able to pick up 8th magnitude Neptune, less than half a full moons width from Mars. Jan. 21: About 45 minutes after sunset, look low in the southwest sky for Venus and then look about 6 degrees to its right for a hairline crescent moon, less than 36 hours past new phase. Venus is actually less bright than usual, but it still vastly outshines all other points of light in the heavens. Because of its relatively low altitude in the sky, the planets appearance in a telescope isnt so good — it remains a shaky, tiny, just barely out-of-round dot of dazzling light that is blurry due to atmospheric turbulence. But Venuss altitude and telescopic appearance will improve greatly in the coming months. And 4 degrees directly below the moon youll also find our old friend Mercury, having faded to magnitude 0.6.
Posted on: Mon, 05 Jan 2015 23:35:23 +0000
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