Bakersfield Night Sky – December 16, 2017
By Nick Strobel
Another semester is finished and holiday thoughts are on my mind, though they have to share time with figuring out how to write about BC for our accreditation report. That and setting up an online astronomy course for next semester. Hmm, not much sleep recovery time in this break! Speaking of sleep, the longest night is in five days (er, nights) from now. Winter for the northern hemisphere officially begins with the December solstice on December 21 (summer for the southern hemisphere). The solstice is the most southern position of the sun with respect to the stars when the sun stops its southward drift. It hesitates briefly, standing still, before starting its northward motion. “Solstice” comes from “sol” (sun) and “stit” (stopped or still). Because we know the sun’s motion so precisely, I can tell you that the solstice will be at 8:28 a.m. Pacific Time on December 21.
Santa will have to make do with the light of just a fat waxing crescent moon (one day before First Quarter) while making his rounds on the night of Christmas Eve but maybe he will have upgraded Rudolph’s nose to the extra-bright red LED advertised on Amazon. On the subject of red lights, Mars is now about halfway between the bright star, Spica, in Virgo and the king planet, Jupiter. You’ll see them in the pre-dawn sky low in the east-southeast. Mars will be visible by three-and-a-half hours before sunrise (or about 3:25 a.m.) and Jupiter will be visible about 40 minutes after Mars. On the night of Christmas Eve, Mars and Jupiter will be 30 minutes apart. You’ll see them get closer together on the sky through the rest of December as they move toward their conjunction on January 6 and 7.
By 9 p.m. all the stars of the Winter Hexagon will be visible (see the star chart below). It is formed by connecting in clockwise order: Capella in Auriga (highest point of the hexagon), Aldebaran at the eye of Taurus, Rigel at the knee of Orion, Sirius at the neck or nose of Canis Major (lowest point of the hexagon), Procyon at the hindquarters of Canis Minor, and Pollux or Castor at the heads of Gemini (see the attached star chart). The brilliant stars of Orion, including the belt stars and the two bright stars at Orion’s shoulders, Betelgeuse and Bellatrix (yes, Harry Potter fans, that bad witch was named after that star), are inside the Winter Hexagon. We won’t have to worry about a bright moon washing out the stars for the next several nights. The moon is at New Phase on the night of December 7/8.
One interesting recent astronomy discovery that came into my inbox is the most distant supermassive black hole yet. This black hole, at the center of the galaxy J1342+0928, has a mass of about 800 million suns and the light from the swirling disk of gas surrounding the black hole tells us that the light has been traveling from a time period of just 690 million years after the Big Bang. The intense light from that swirling disk makes the galaxy be a quasar.
Besides being the most distant supermassive black hole discovered that makes the question of how supermassive black holes could get so large in so short a time even more urgent, the quasar light shines through gas clouds between us and the quasar that are an approximately 50/50 combination of neutral and ionized hydrogen. The big deal about that is that it tells us J1342+0928 resides in the “epoch of reionization”. The time of the epoch of reionization is something we’ve been trying to pinpoint for several decades. This is when the universe transitions from having the intergalactic medium (stuff between the galaxies) be mostly neutral hydrogen gas to be mostly ionized hydrogen (the electron knocked out of the atom) as it is today. Pinpointing the time of the epoch of reionization will help us choose between the various proposals of what could supply the tremendous amount of ultraviolet light needed to zap the electrons out of the hydrogen in the early universe: stars in dwarf galaxies, quasars, the elusive “Population III stars”, or combinations of these.
Although we are constantly being bombarded by messages to spend, spend, spend during this holiday season, I hope that you will consider boosting the economy in a different fashion by donating to a worthy charity in honor of someone else. Many blessings to you this holiday season and I hope you all have an excellent 2018!
Director of the William M Thomas Planetarium at Bakersfield College
Author of the award-winning website www.astronomynotes.com