Bakersfield Night Sky – December 15, 2012
By Nick Strobel
The fall semester is now over at Bakersfield College but the K12 schools are still in session for another week. As we approach the end of 2012, I'm sure that some students are wondering if they need to study for their final exams since the world is supposed to end on December 21st. Well, as I have told my students at the beginning of every semester since this <2012 cosmophobia craziness began a few years ago, "No, the world is not going to end in 2012, so, yes, you need still need to do your studies and get that college degree!" [Hmm... All this 2012 doomsday stuff makes me wonder if some of our congressional leaders have been duped by the 2012 doomsday sites and that's why they're not serious about settling the "fiscal cliff" problem.]
Some fuel to the fire of the 2012 scare has probably been some of the stories of rather close fly-bys of small asteroids. One small one called 2012 XE54 was discovered just a week ago and it passed by Earth on December 11th at a distance slightly more than halfway to the Moon. That one was discovered and passed by too quickly for the 2012 doomsday folk to latch onto it but they have latched onto asteroid 2012 DA14 as a 2012 Earth destroyer. Well, that 46-meter diameter asteroid does pass very close to the Earth, just 13,000 miles from the Earth, but it will do that on February 15, 2013 and we know its orbit well enough to say that it is definitely NOT going to hit us. Also, its orbit is such that 2012 DA14 will not hit any of our satellites either. The 2012 doomsday people also like asteroid 4179 Toutatis, a mountain-sized hunk of rock that passed by the Earth on the night of December 11-12th at a distance of 4.3 million miles. Oops! That date has already come and gone (and we're safe for another 600 years or so from a Toutatis impact), so what other object can the doomsday prophets point to that will crash into the Earth soon?
Well, another near-Earth asteroid in the news earlier this year was asteroid 2011 AG5 but it was not part of the 2012 doomsday event because its supposed collision date was way off in 2040. Further observations of 2011 AG5 have pretty much ruled out a collision in 2040 but we'll know with 100% certainty when the asteroid passes near us in early February 2023 (ten years after 2012 DA14's close passage). The asteroid 99942 Apophis has been in the news too and it will fly by the Earth on January 9th at a distance greater than 37 times the Moon's distance. A much closer fly-by will occur in 2029 when it will be less than 20,000 miles from the Earth. Apophis was in the news because there was a small possibility for an impact in 2036. Several years back observations of Apophis had reduced the chance of an impact in 2036 to 1-in-250,000. The observations of its close fly-by next month will undoubtedly reduce the chances even more as we further improve our knowledge of its orbit. Well, darn! Isn't anything going to hit us this month? Nope. And none of the other nasty Earth-destruction things of the 2012 craze are going to happen either.
Having discounted all the Earth impact scenarios, does that mean we don't have to worry about any asteroid impacts at all? No. There are asteroids that do pass close to the Earth, we will be hit sometime in the future, and an impact of something as small as 2012 DA14 would be equivalent to 2.4 megatons of TNT---enough to wipe out a city the size of Bakersfield. NASA's Near Earth Object Program headquartered at JPL is tasked with finding hazardous asteroids and determining their orbits to assess how hazardous they are. Each day they update their table of close approaches at http://neo.jpl.nasa.gov/ca . No city-destroying (or larger) impacts are expected in the next 100 years.
About a year and a half ago, I listed the steps I take to check out the stories of Earth impacts in the popular media. As we draw closer to December 21st, perhaps it would be worthwhile to give them again. In addition to the Near Earth Object Program website mentioned above, I check out the IAU's Minor Planet Center at www.minorplanetcenter.net and Sky and Telescope's news section at www.skyandtelescope.com for something that hasn't been reported yet in the weekly news email they send out. To find out more about the effects of an impact on Earth, see the Earth Impacts webpage on my Astronomy Notes site at www.astronomynotes.com .
One thing that I know will happen on December 21st is the December solstice. That is when the Sun will appear to stop its southward progression among the stars and start heading northward again. For us in the northern hemisphere that date is the official start of the season of winter. Because the official start of winter depends on the motion of the Sun with respect to the stars as seen from Earth, we can quote the start of the season down to the minute: winter starts at 3:12 AM Bakersfield time. One other event on December 21st is the Kern Astronomical Society's "End of the World Party" complete with stargazing through the club's telescopes. KAS will celebrate the rollover to the new Baktun in the Mayan calendar at Ethel's Old Corral on Alfred P Harrel Hwy starting at 3:45 PM with solar observing followed by stargazing in the evening. See the KAS website at www.kernastro.org for more details.
The first star chart below shows the view of this evening's sky and the following nights. Jupiter will be a good sight to look at through the KAS telescopes on the 21st. It is the brightest "star" in the evening sky and it will be next to Taurus' head. Tonight the very thin Waxing Crescent Moon will be low in the southwest sky above orange-red Mars. The Moon will set about two hours after sunset. By the 21st, the Moon will be in the waxing gibbous phase among the dim stars of Pisces below the much brighter Pegasus. The Waxing Gibbous Moon will pass next to Jupiter on the night of December 25th. Two nights later it will be full phase at the feet of Gemini and a few nights later it will be about half-way up in the eastern sky near Regulus in Leo when midnight revelers ring in the New Year.
In the early morning sky, SaturnVenus, and Mercury are in the eastern sky. Saturn will become visible at the edge of Virgo at about 3:45 AM followed by super-bright Venus at the head of Scorpius after 5:30 AM and then Mercury at about 6:10 AM also in the head of Scorpius. On the morning of December 22nd, Venus and Mercury will have moved enough so that they will form an equilateral triangle with the red heart of Scorpius, the star Antares. The second chart below shows the view for that morning.
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. I also hope you all 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