Bakersfield Night Sky – August 20, 2011
By Nick Strobel
Tickets for the entire Fall schedule of evening Planetarium shows are now available from the BC Ticket Office. All shows are on a Thursday evening: September 22nd is Ice Worlds, October 20th is Dawn of the Space Age, November 17th is Black Holes, and December 1st and 8th are Season of Light. Doors open at 7 PM and are closed at 7:30 PM with no late admittance. Prices remain the same as last year: $6.50/adult and $4.50/senior and children 5 to 12 years of age. Shows usually sell out weeks in advance so don't delay in getting your tickets! For more information about each of the shows, go to the William M Thomas Planetarium's website at www.bakersfieldcollege.edu/planetarium and select the links to each show. In space exploration news, there are several new developments.
The Juno spacecraft is now heading toward Jupiter with an arrival date in July 2016. Why Jupiter? Jupiter played important roles in the formation of the other planets because it formed first and it is the largest planet. Juno will be able to find out more about what the interior of Jupiter is like and how its magnetic field works by very precisely measuring the gravity and magnetic fields as it orbits Jupiter. Most of the exoplanets discovered so far are similar to Jupiter in size and mass, so better understanding Jupiter gives us a better handle on the exoplanets. Juno will also be able to finally determine the amount of Oxygen (most probably locked up in the form of water) in Jupiter which will tell us not only about the formation of Jupiter but the rest of the solar system, including Earth, as well. Juno will be able to answer these questions by having the sensitive instrumentation and orbit to probe Jupiter's interior better than previous spacecraft. The previous orbiter called Galileo studied Jupiter's upper clouds and Jupiter's moons in the 1990s.
There are several firsts with Juno. Juno will be the first spacecraft to go into a polar orbit (i.e., orbiting pole-to-pole instead of roughly along its equator) around a gas giant planet, it will be the first with a specially designed vault to shield the electronics since Jupiter's radiation environment is extreme, and it will the first outer solar system spacecraft using solar power. Previous spacecraft to the outer planets including the Voyagers now leaving the outer boundary of the solar system and the Cassini spacecraft still orbiting Saturn and returning great science years beyond its original mission, all have used nuclear power to generate the electricity they need. The solar arrays are very large and also much more efficient than the ones set up on many house rooftops or over the northeast parking lot at BC. Sunlight at Jupiter is diluted by about 25X from the sunlight at Earth because of Jupiter's distance from the Sun. At Jupiter's distance, the three 28-foot solar arrays will generate about 420 Watts of power for all of Juno's needs. Knowledge gained by designing those solar arrays are going into the commercial sector to improve solar power efficiency on Earth.
Earlier this summer an Earth-observing science satellite called Aquarius was put into orbit around Earth to map out the global ocean circulation and how water and energy are cycled between the surface and the atmosphere. This is crucial information needed to understand the global climate. After the past several weeks of checking out the spacecraft and calibrating the instruments, science observations are expected to begin this week. Aquarius will measure changes in the density of the ocean water by measuring the "sea surface salinity", the amount of salt per gallon of water at and near the surface of the ocean, at many thousands of points over ALL of the oceans. The sensitivity of the measurements is that Aquarius can detect a change equivalent to a pinch of salt in one gallon of water (0.2 grams of salt per kilogram of water for you metric system lovers). About a quarter of the global ocean surface has no salinity data at all. Aquarius will measure all of the ocean surface every seven days, so Aquarius is certainly going to fill in big gaps of our knowledge of the global water cycle and global climate.
A little later this year, the Mars Science Laboratory (MSL), named Curiosity, will be heading toward Mars. We finally now know where it's going to explore. Four sites were in close competition and the Gale Crater finally won the heated debates that took place over the past three years. All four sites are no higher than an elevation of 0 km and also within 30 degrees latitude of the equator to stay warm enough all martian year round. Gale Crater is 96 miles across with a large mountain that appears to be the remnant of an extensive series of deposits. The layers at the base of the mountain contain clay and sulfates that very likely formed in liquid water. Curiosity will spend one martian year (almost two Earth years) determining if that site could have supported life and if the conditions are right for preserving clues of any possible past life. It will have the instruments needed to find any organic molecules in the rocks and soil. Now, not all organic molecules are the result of biology but besides water, life forms are going to need organic molecules. You can read the "Life Beyond Earth" section of my Astronomy Notes site at www.astronomynotes.com for more on that. Gale Crater is not one of the craters in a very recent NASA news conference that seem to have evidence of present-day liquid salty water. Those craters are outside the 30 degree latitude limit for a MSL landing site.
One question that might be on the mind of budget-conscious citizens is how are we paying for all of these space missions? Well, all of the ones launching this year and next have already been paid for. Each space mission is the result of ten or more years of development and building by hundreds to thousands of people in various institutions and engineering companies. My worry is what we're going to see in the next decade and beyond. There is very little in the pipeline now. As I'm gearing up for another school year, I'm wondering what sort of possibilities we as a nation are creating for all of today's high school and college students. Something to think about as the political rhetoric continues to heat up...
For the night sky what do we have? August is the last month for decent views of Saturn as the Sun appears to close in on Saturn's position in Virgo. By the time that the sky gets dark enough to even spot Saturn this evening, it is about 20 degrees above the western horizon. By an hour after sunset, Saturn is only 13 degrees above the horizon—that's just a little bigger than your clenched fist held at arm's length. Saturn continues creeping away from Porrima on the right side of Virgo, heading toward Spica, the bright star on the left side of Virgo, for a rendezvous in November. See the second chart below. The asteroid Vesta being explored by the Dawn spacecraft is still bright enough to see without binoculars under a truly dark sky in the lower half of Capricornus over in the southeast at 9 PM. See the finder chart from my previous column.
The sky has shifted enough for Jupiter to rise a little before midnight. Jupiter is below the stars of Aries and just above the head of Cetus. Jupiter will be the very bright star you see low in the east around midnight. Tonight, the Third Quarter Moon will rise about twenty minutes after Jupiter, so if you can see the Moon, Jupiter will be the very bright star to the right of the Moon. The Moon will be a little to the right of the Pleiades cluster at the shoulder of Taurus. The Moon will be in new phase on August 28th. Mars rises a little after 3 AM near the middle of Gemini. The first chart below shows the pre-dawn sky at 5 AM when Mars will be high enough to spot easily and Jupiter will be two-thirds the way up in the sky high in the south-southeast. A thin sliver of the Waning Crescent Moon will pass next to Mars on August 25th (also shown in the first chart below).
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