Bakersfield Night Sky – December 2, 2017
By Nick Strobel
The lecture/lab portions of the semester are now done, just the final exams to go! Last Thursday, November 30, was the first showing of the popular holiday tradition, “Season of Light” at the William M Thomas Planetarium. The second showing will be this Thursday on December 7 at 7:30 p.m. You can purchase tickets at the BC Ticket Office or online at Vallitix. The next season of shows will start in February.
Tomorrow night is the last full moon of the year and this full moon will happen when the moon is at perigee, its closest distance to us in its elliptical orbit. It will be next to the bright star, Aldebaran, at the eye of Taurus. Those in Alaska and far-east Asia will see the full moon cover up Aldebaran near their time of just before sunrise. This coming week on the nights of December 8 and 9, we will see the waning gibbous moon on either side of the bright star, Regulus, in Leo—the moon will be to the right of Regulus on December 8 and to the left of it on December 9 (see the first star chart below). Those in eastern Europe and northwestern Asia will see the moon cover up Regulus. Some people get all the luck!
From now to December 16, you may be able to catch sight of meteors of the Geminid meteor shower. The Geminids will peak the night of December 13-14 and the moon will be just a waning crescent, so the night should be dark enough to see most of the meteors in this shower. The Geminids are usually quite numerous, so check it out if the weather cooperates (see the second star chart below).
The interstellar asteroid I wrote about in my previous column continues speeding out of the solar system. It has a name: ‘Oumuamua which is Hawaiian for “a messenger from afar arriving first.” ‘Oumuamua passed Mars’s orbit on November 1 and it will pass Jupiter’s orbit in May 2018 but its path is 20 degrees above the plane of the planets, so it will be nowhere close to the planets. Besides being the first interstellar visitor to our solar system we’ve seen, ‘Oumuamua is also unusual because of its very elongated shape—ten times longer than it is wide. The most elongated objects in our solar system are at most three times longer than their width. It also has a reddish tint to it from the irradiation from cosmic rays over hundreds of millions of years.
Speaking of red objects, the red planet Mars was in the news this past week because it looks like the dark streaks that form on slopes and lengthen in the spring and summer and then fade away in fall, are probably not due to water seepage as originally hoped. Features like this on Earth are due to seeping water but on Mars dark streaks could form from sand flowing down the slopes. One key piece of evidence for this is that the streaks form on slopes as steep or steeper than the “angle of repose” for sand dunes. The “angle of repose” is the steepest slope possible for a feature made of loose materials before gravity causes the loose materials to flow downhill. Water-formed features would be able to flow down shallower slopes.
An earlier study last year also showed that any water that could be associated with the dark streaks would have to be less than three percent, or drier than the driest desert on Earth. Although the presence of water cannot be ruled out, it is very likely that any water in the streaks would come from water sucked from the air by salts in the soil in a process called “deliquescence” instead of from underground water aquifers. What is still hard to understand is why the streaks darken and then fade and why the streaks appear on some steep slopes but not others. If deliquescence is the cause for the streaks, then the streaks should form on other slopes too. Research continues!
One other news item about Mars is that NASA announced that it will build a sophisticated spectrograph for Japan’s MMX mission to Mars’s moons, Phobos and Deimos. MMX will launch in 2024 and arrive at Mars to study the moons several months later. MMX will touch down on the closest moon, Phobos, pick up a sample and return the sample back to Earth in 2029.
In our night sky you will see Mars rising in the pre-dawn sky about three hours before sunrise to the left of the bright star, Spica, in Virgo (see the first star chart below). About an hour and a half later, the over twenty times brighter Jupiter will be visible low in the east in between the stars of Virgo and Libra. Over the following early mornings of December you will see Mars get closer to Jupiter. The waning crescent moon will pass by them on the mornings of December 13 and 14.
Director of the William M Thomas Planetarium at Bakersfield College
Author of the award-winning website www.astronomynotes.com