Bakersfield Night Sky – December 17, 2016
By Nick Strobel
Bakersfield College finished another semester of learning last week and we’re looking forward to more learning next semester or as Jack Hernandez reminded us in a recent Community Voices piece: helping students on their paths to freedom through education. Next Wednesday on December 21 will be the longest night of the year in the northern hemisphere, the winter solstice. This marks the farthest south position of the sun with respect to the celestial equator. Since the winter solstice begins our season of winter, I can tell you that winter begins at exactly 2:44 a.m. Pacific time. For those in the southern hemisphere, that time marks the beginning of their season of summer.
The night of December 20/21 will see the moon in third quarter phase. On Christmas Eve, the moon will not be giving much help lighting up the rooftops for Santa because it will be in a thin waning crescent phase. He’ll have to make due with the light from Rudolph’s nose or maybe he can use one of the tactical flashlights that have been the subject of numerous spam emails filling my inbox for the past few months. Tonight you’ll see the moon in a waning gibbous phase near the brightest star of Leo, Regulus, after midnight. Regulus will be the bright star about half a fist width (two knuckles) at arm’s length to the lower left of the moon. The moon will be at new moon phase on December 28, so it will be a thin waxing crescent low in the west in the early evening sky of New Year’s Eve.
In its smaller orbit around the sun, Venus is steadily catching up to Earth. As it does so, it is getting brighter and higher up in the western sky in the evening. Venus will be the brightest “star” in the sky after the sun sets (see the first chart below). A view through a telescope will show Venus becoming skinnier as the month progresses. Tonight Venus is in the middle of Capricornus. By the end of the month, Venus will be on the far left side of Capricornus as it catches up to the orange-red planet that is now among the dim stars of Aquarius.
Mars will get dimmer over the following weeks but it is still much brighter than the dim stars of Aquarius. To the left of Venus and Mars is the bright star Fomalhaut in Piscis Austrinus, a young hot star with a large planet orbiting it. By 10 p.m. all of the constellations in the Orion group will be visible in the east (see the second chart below). At the center will be brilliant Orion with the three belt stars at his waist pointing up to the upper right toward Aldebaran, the orange-red eye of Taurus, and pointing down to the lower left toward Sirius, the brightest star in the night sky at the nose of Canis Major. Moving clockwise from bright Sirius, will be Procyon in Canis Major, Pollux and Castor at the heads of the Gemini twins, Capella in Auriga, Aldebaran in Taurus and Rigel at Orion’s left knee. The gorgeous Pleiades star cluster is in Taurus’s shoulder. A star chart showing the 10 p.m. sky is posted below.
In the early morning sky Jupiter will blaze away in the eastern sky becoming visible among the stars of Leo shortly after 3 a.m. Jupiter will be the brightest “star” in the early morning sky. Saturn went behind the Sun on December 10 and may be visible shortly before sunrise by about Christmas morning. Hopefully, I’ll be sleeping comfortably in my mother’s house at that time if a winter storm hasn’t closed off the roads to Oregon.
The Cassini spacecraft orbiting Saturn since 2004 has returned some amazing and beautiful pictures of Saturn’s polar hexagon cyclone from a new set of orbits that carry it nearly perpendicular to the plane of the rings. Each side of the hexagon cyclone at Saturn’s north pole is about 8600 miles long, or longer than the diameter of Earth. The strange hexagonal shape probably is the result of large changes in the direction of the winds at high latitudes but it is not known why such features are not seen on the other large planets or even at Saturn’s south pole. The north pole hexagon was seen by the two Voyager spacecraft in 1981 and 1982, so the cyclone has been around at least a few decades and there’s no sign of it weakening.
These highly-tilted orbits pass to within 57,000 miles from the cloud tops and just 6800 miles from the center of Saturn’s outer F-ring. The F-ring is a narrow ring shaped by the gravity of two tiny moons on either side of the narrow ring. The “shepherd moons” create bright streamers, tenuous filaments, channels, and ripples in the F-ring.
Next April a close flyby of Saturn’s largest moon Titan will change Cassini’s orbit so that Cassini will thread the narrow gap between the innermost rings and Saturn’s cloud tops. These polar orbits will give scientists the best ever views of the rings and even closer views of the polar hexagon cyclone. On September 15, Cassini will plunge into Saturn’s atmosphere as a way of preventing Cassini from possibly contaminating Saturn’s possibly habitable moons in the far future.
The last show of the fall season at the William M Thomas Planetarium was “Season of Light”. The last part of the show looked at one possible explanation for the “Bethlehem Star”, the heavenly sign that heralded Jesus’ birth as described in the second chapter of Matthew in the Bible. The show settled on a conjunction of Venus and Jupiter as being the best option.
Several years ago I wrote an article about the various astronomical explanations for the Bethlehem Star. It is posted on the William M Thomas Planetarium website for the next few weeks. A crucial part of any Bethlehem Star theory is when King Herod died. Although my research comes up with a different date for Herod’s death than in the “Season of Light” show, and, therefore, a different astronomical explanation, I’m comfortable with showing the Season of Light’s explanation because it includes the questions that are asked to determine plausible explanations. It notes that the historical data are not good enough to come up with a conclusive proof and that the real point of the story is not to be an astronomy or history textbook.
It is my hope that we all will remember the real point of the story and re-align our lives closer to the example of the one at the center of the Christmas story, who defined glory in a very different way than what is celebrated by our world today. Have a blessed and joyous holiday season and safe travels!
Want to see more of the stars at night and save energy? Shield your lights so that the light only goes down toward the ground. See www.darksky.org for how.
Director of the William M Thomas Planetarium at Bakersfield College
Author of the award-winning website www.astronomynotes.com