Bakersfield Night Sky – July 21, 2012
By Nick Strobel
In this evening's sky are the two planets that are making news: Mars and Saturn. In just two weeks the largest craft to ever land on Mars, the Mars Science Laboratory, will arrive at Mars. My previous column detailed all of the innovative things and techniques that will be used to land the rover on the surface. The Mars Science Laboratory, aka "Curiosity", will determine Mars' "habitability", i.e., determine if Mars ever had an environment able to support any kind of life. It will use the largest, most advanced suite of instruments ever sent to the martian surface for that task during at least a full martian year (687 Earth days). Signals from Mars of Curiosity's landing are expected at 10:31 PM Pacific Daylight Time on the evening of August 5th.
The other planet in the news is Saturn, or actually, its largest moon called Titan. With a nitrogen-rich atmosphere even thicker than Earth's atmosphere, it is thought to be like the Earth was before life developed and changed the chemistry of our atmosphere but Titan is in deep-freeze. At 290 degrees F below zero, Titan is so cold that water on the surface is as hard as rock and methane flows as a liquid. Very careful measurements of how much Titan flexes from Saturn's gravity in its slightly elliptical orbit show that Titan joins four other moons in our solar system (Europa, Ganymede, Callisto, and Enceladus) in having a layer of liquid water below its surface. The water layer is thought to be about 30 to 60 miles below the surface. We're not sure if the liquid water layer is in contact with the rocky interior or if the water layer is sandwiched between two ice layers. Being in contact with a rocky interior could possibly supply the water with nutrients simple life forms could use. Even more amazing is the incredible degree of precision required to make the measurements. Scientists on Earth hundreds of millions of miles from Saturn had to detect changes in the Saturn-orbiting spacecraft called Cassini as small as 0.0002 mile per hour. That's two ten-thousandths of a mile per hour.
You will see Mars and Saturn as two ends of a triangle and the bright star, Spica, at the other end of the triangle in the west-southwest after sunset as shown in the first chart below. The triangle will be tipped over on its side so Saturn and Spica will be almost in a vertical line with Saturn on top. Over the next several weeks, the triangle will get shorter as Mars moves closer to Saturn and Spica on the sky. Closer to the western horizon, see if you can spot the slim Waxing Crescent Moon. On July 24th, a much fatter Waxing Crescent Moon will make a quadrangle with Saturn, Mars, and Spica and the Moon will be at first quarter phase the following night. On July 28th, the Kern Astronomical Society will hold its monthly free public star party at Russo's Books in the Marketplace at 9000 Ming Ave from dusk to 10 PM. See the KAS website at www.kernastro.org for a detailed map of the free public star party location. By then the Moon will be in the south at 9 PM as a Waxing Gibbous just above Antares, the bright red heart of Scorpius. A chart for that night is the second chart below.
In the pre-dawn sky, you will see the two brightest planets, Jupiter and Venus, low in east. Venus continues to move away from Jupiter. They are now about a fist at arm's length apart from each other on the sky and will be half again as much by the end of the month. Jupiter is close enough to the orange eye of Taurus, the star Aldebaran, that they should both fit within the same field of view of your binoculars—see the third chart below. The Waning Crescent Moon will pass by Jupiter, Aldebaran, and Venus in the second week of August. The Moon will be full the night of August 1st/2nd.
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