Thursday, January 1, 2015

The January Sky

With new month of January upon us, people in the Northern Hemisphere will still be treated to some of the longest nights of the year as, even after the solstice, the Sun won't be moving North very much anytime soon. Basically, January is still pretty much a story of steady 15 hour nights, give or take a few minutes at most. So, with all of this night, what's there to see?

Cool Constellations
By nightfall in January the fall constellations are all very well-placed for early (emphasis, early!) evening viewing. First up, we will have one last chance to see the Summer Triangle, provided you have a good West horizon. Hurry, though, it will quickly disappear (at least in the West) for good by month's end. Moving onto more mainstream celestial landmarks for this time of year, the Great Square of Pegasus is rapidly sinking in the West and the Big Dipper is starting to climb in the Northeast. Starting at the Great Square, look at the double string of stars coming of third base as they constitute Andromeda. High in the North is ‘W’-shaped Cassiopeia, house-like Cepheus, and a twisted ‘V’ of stars, the mythological hero Perseus. Below Perseus is the bright Capella, alpha Auriga, and below his feet, the cloudy patch that is the Pleiades. In the early evening, the Southwest is a dark void populated by the dim constellations of Capricorn, Aquarius, Pisces, and Cetus, all 4 of which are to soon disappear. If you stay up a little later as in a couple of hours after nightfall (which is no chore this time of year), you'll see all the winter favorite like unmistakable Orion in the South, which also serves as a winter signpost to the stars. From Orion, follow a line from his belt down to blazing blue Sirius, alpha Canis Major. Following that line up will bring one to Aldebaran, alpha Taurus the bull. Imagining a line starting at bright blue Rigel (Orion's left foot) through red Betelgeuse (Orion's right shoulder) will bring you to Castor and Pollux, alpha and beta Gemini. Other winter favorites to look for include Canis Minor, Cancer, and even Leo if you wait into the night a little longer. Early birds? Well, getting up just before the Sun will bring a spring preview in the form of Virgo, Bootes, Corona, Hercules, Corvus, and even Vega just ahead of the rising Sun.

Planetary Perceptions
On the planet front, January is looking to be the first true 5 for 5 planet month in some time. At dusk, the two planets closest to the Sun, Mercury and Venus, are barely visible at the start of the month. However, as the days pass, they will both start to dramatically rise, with Mercury reaching peak height at mid-month and Venus continuing to climb all month long. Additionally, Mars continues to hang low, barely moving relative to the stars, in the Southwestern sky, setting about 2 ½ hours after the Sun all month. Moving later into the night, Jupiter is up for most of the night as it moves toward opposition, which will take place next month. Last but not least, Saturn continue to re-emerge from the Sun in the predawn sky. By month's end, the ringed wonder is rising nearly 5 hours ahead of the Sun. The best part: thanks to the late sunrises this time of year, one need not get up obscenely early to catch it.

Fun Thing to Do
With the longest nights of the year upon us, this is the time when you can see the same star twice in one night, as is on the set in the evening and on the rise in the morning. Despite this being the first month of winter, the summer stars are still visible in the sky at dusk. The stars of the Summer Triangle make perfect targets because of their brightness. As for what to do, simply go out and observe the stars of the Triangle (Vega is best as it is the brightest and will be first to rise in the morning). That done, either go to bed or stay up and enjoy the night until just before sunrise. At that point, go out and look in the Northeast for your chosen star's return to the sky. How many people can say they saw the same star twice in one night that way?

Tonight's Sky for January 1: Ceres Discovered (1801)
It was on this date in 1801 that the largest asteroid, Ceres, became the first asteroid to be discovered.

At the time, there was a hypothesis known as the Titus-Bode Law (since discredited), which states that distances of planets from their parent star and relative to each other can be determined by mathematical formula. With the 5 classical planets, the pattern seemed to hold true save a gap between Mars and Jupiter. When Uranus was discovered, by pure chance, it fit the pattern, increasing belief in the Titus-Bode Law and causing a renewed interest in finding the missing planet that was hypothesized to be located between Mars and Jupiter.

It was on New Year's Day 1801 that Giuseppe Piazzi discovered this 'planet,' which he named Ceres after the Roman goddess of agriculture. The largest body in the asteroid belt, Ceres contains about a third of the Asteroid Belt's mass and its diameter is about a third that of the Moon.

Initially classified as a planet, Ceres retained that status for about 50 years. The turning point: the discovery of more small bodies in the same region, which eventually caused astronomers to realize that a whole new class of objects, asteroids (meaning 'star-like') existed in this region. In time, Ceres was reclassified as an asteroid and became officially known as 1 Ceres for the fact that it was the first asteroid ever discovered. Come 2006 and the whole Pluto reclassification/definition of 'planet' controversy, Ceres was reclassified also, getting promoted to dwarf planet. To date, Ceres is the only dwarf planet in the inner solar system.

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