Bakersfield College

October 6, 2012

Bakersfield Night Sky – October 6, 2012
By Nick Strobel

The days are growing shorter and the rate of shrinking daylight is more noticeable around this time of year near the equinox. Summer wants to hang on, though, as I brace myself for another triple-digit day. Fortunately, there's AC during the day and the nights do cool off a bit to provide some relief.

Venus and Jupiter continue their dominance in our night sky, far outshining any of the true stars. Jupiter will be visible in the starting at about 10:15 PM. As shown in the first star chart below, Jupiter is between the two horns of Taurus. During September, it was slowing down its eastward drift among the stars as the Earth was catching up to it in our faster and smaller orbit around the Sun. Jupiter is now appearing to move backward or westward among the stars (retrograde motion) as we pass by it this next few months. During October and November Jupiter will grow even brighter, reaching its peak brightness around Thanksgiving time. Its retrograde loop will carry Jupiter back past the Hyades cluster in Taurus' head by the third week in January.

Venus becomes visible in the east at about 4:15 AM tomorrow morning, almost three hours before sunrise. Venus is now past its very close conjunction with the bright star Regulus at the end of the sickle part of Leo, but they both should just barely fit within the same field of view of your binoculars tomorrow morning. Although Venus will fade slightly as it moves farther from Earth in its faster, inner orbit, Venus will still be the brightest star-like object in the sky and only the Moon will be brighter than it. By the end of October, Venus will be in the constellation Virgo.

The Waning Gibbous Moon will become visible tonight at about 11:30 PM. Tonight it is at the foot of the twin Castor in Gemini (see the first star chart below). The following night it will rise after midnight as a Third Quarter (or Last Quarter) Moon next to the twin Pollux of Gemini. At third quarter phase, the Moon's left half is lit as it makes a 90-degree angle with respect to the Sun on our sky, so we see half of its daylit side facing us. As the angle between the Sun and Moon shrinks over this week and the next, less and less of the daylit side will face us and we will see the crescent Moon get thinner and thinner. On the morning of October 12th, the Waning Crescent Moon will be near bright Venus. The phase cycle will start over with the New Moon on October 15th.

Mars remains low in the southwestern sky, setting two hours after the Sun does. Mars is slightly in front of (to the right of) the head of Scorpius. Mars will pass through the head of Scorpius from October 9th through the 13th and it will be just above the bright red star Antares at the heart of Scorpius on October 20th. Antares means "rival of Mars" so the night of October 20th will provide a good placement of Mars and Antares for you to compare the two, though Mars is certainly not at its brightest. In fact, Antares will appear slightly brighter than Mars. Antares is a red supergiant with a diameter almost as large as Jupiter's orbit around the Sun. See the second star chart below for the evening October view.

On Mars, Curiosity continues moving toward Glenelg in Gale Crater. Last week Curiosity found the remains of an ancient streambed. The size of the gravel in the streambed tell us that the water moved at about two miles per hour and the stream was somewhere between six inches to three feet deep. The streambed is part of an alluvial fan of material washed down from the rim of Gale Crater. From orbit a number of other channels are seen in the alluvial fan between the rim and the conglomerates at Curiosity's location suggesting that water flows continued or repeated over a long time. More about Curiosity's exploration of Mars' past (present?) habitability of at least microbial life can be found at http://mars.jpl.nasa.gov/msl .

High overhead in the evening is the Summer Triangle made of the brightest stars in three constellations: Vega in Lyra, Deneb in Cygnus, and Altair in Aquila. If you face southwest, Cygnus looks like a cross with bright Deneb at its top. Cygnus is actually a swan with Deneb at its tail and Albreo at its beak. Extend the crossbeams out and you have the wings of Cygnus, so the swan is flying down toward the southwest. The area of Cygnus' left wing (or the right side of Cygnus as seen by us) is where the Kepler spacecraft continues to search for Earth-size planets in the stars' habitable zones (the region around the star where the surface temperature on a planet would be just right for liquid water to exist). The third star chart below shows the zenith view and also it includes Kepler's field of view.

Seventy-seven planets have been confirmed including two that orbit a binary star system with one of the planets in the binary system's habitable zone. Other single planets have been found around binary stars but this multiple-planet system (called Kepler-47) is making scientists re-examine how planets can form in binary star systems. Originally, we thought stable planet orbits were very difficult to create in binary star systems and systems with multiple planets would be near impossible. However, it now appears that stable orbits in binary systems are easier to come by than we thought. That's good because there are more stars in binary or triple star systems than solitary stars like our Sun in the Milky Way galaxy. Though 77 planets may seem like a small number, just wait! There are over 2300 candidate planets (as of last February) that need to be followed-up for confirmation and there will likely be several hundred more candidate planets announced in the next few months. The possible real estate to look for habitable worlds continues to increase! The Kepler mission's website is http://kepler.arc.nasa.gov .

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.
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Nick Strobel
Director of the William M Thomas Planetarium at Bakersfield College
Author of the award-winning website www.astronomynotes.com

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