Bakersfield College

July 20, 2013

By Nick Strobel

Tonight is the free monthly public star party with the Kern Astronomical Society (KAS) that takes place from 8:00 PM to 10 PM or so, depending on foot traffic, at Russo's Books in The MarketPlace. On tap will be a big Waxing Gibbous Moon just a couple days from full phase, Saturn and its lovely rings and larger moons, a close pairing of Venus with the bright star Regulus at the end of the Sickle in Leo, globular clusters such as M13 in Hercules high overhead, open clusters in Sagittarius and Scorpius, and maybe some galaxies and nebulae, though the city lights and moon light would make seeing galaxies and nebulae a bit difficult. The first star chart below shows the southwestern sky at around 9 PM. Thsecond star chart below shows the eastern and southeastern sky at 9 PM. At the KAS star party you can also buy a raffle ticket (or more than one) to possibly win a nice, good-size telescope as a Christmas present for yourself or someone else you know. All proceeds for the raffle will go toward funding the Astronomy Day event in April. The raffle drawing will be in early December.

Low in the west you will see blazingly bright Venus and the bright star Regulus about a thumb width at arm's length apart from each other. The next couple of nights they will be even closer together as Venus passes over Regulus. Higher up in the southwest you will see a large triangle of bright points made of Saturn at the lower left corner, the star Spica at the lower right corner about a fist width at arm's length from Saturn, and the brightest true star in our evening sky, Arcturus, at the top point of the triangle two-thirds of the way up in the sky. Almost at the zenith (point directly overhead) is Hercules with the gorgeous globular cluster M13 at the right edge of the keystone part of Hercules.

Scorpius and Sagittarius are in the direction of the Milky Way's (our home galaxy) center which will be in the southerly direction at the time of the free public star party this evening. As shown in the second star chart below, the bright Moon will be right above the Teapot part of Sagittarius tonight so it will be hard to see anything else in that direction this evening but the Moon will look great through the KAS telescopes! In the eastern sky about half-way up will be the Summer Triangle of bright stars made of Deneb at the tail of Cygnus the swan on the left corner of the Summer Triangle, Altair in the middle of the neck of Aquila the eagle in the lower right corner of the Summer Triangle, and Vega at the base of Lyra at the top corner of the Summer Triangle. The second star chart below shows the location of the Ring Nebula (M57) at one end of Lyra. You might try to see if it's visible in the KAS telescopes but, again, that bright Moon and the city lights might wash it out.

The Ring Nebula is the remnant of a dying star similar to the mass of our Sun that has blown off its outer layers in a gentle burst called a planetary nebula. It's not a supernova remnant---it takes a star much more massive than the Sun to have an explosive death. The Ring Nebula is about one light year across (over 790 times the diameter of Pluto's orbit) and is about 2300 light years away, so we are seeing it as it was 2300 years ago. At the center of the Ring Nebula is the tiny exposed core of a now dead star called a white dwarf. You need a large telescope and a timed exposure of an attached camera to pick out the white dwarf. The white dwarf has roughly as much material as the entire Sun shrunk down to about the size of the Earth. The Ring Nebula formed "recently", within just 1600 years or so ago, so the white dwarf is still quite hot: about 125,000 K, or over 20 times hotter than the surface of the Sun.

The third star chart below shows the early pre-dawn morning. Of particular interest in the pre-dawn sky will be the close pairing of Jupiter and Mars low in the eastern sky about an hour before sunrise. They will be at the foot of one of the twins of Gemini and they'll be best viewed through binoculars or a small telescope. For the next couple of mornings, the two planets will be about a pinky width at arm's length apart from each other.

Mars was in the news last week because of NASA's announcement of a new rover mission that is expected to get to Mars in 2020. It is currently going by the very catchy name of "Mars 2020" but I'm sure some grade school child will come up with a better name in a naming contest like what was done for the past rovers. Following up on the current Curiosity rover's successes, the new rover will use the same general landing technology and rover chassis. It will probably use the same radioisotope thermoelectric generator power source that Curiosity has but solar panels might be used like those on the Opportunity rover still roaming about the rim of Endeavour Crater. If they use solar panels, the panels will be mounted so that they can be tilted to follow the Sun for more power and to remove dust. The new rover will have even greater capability than Curiosity to study the rocks at an even finer scale and to find potential biosignatures in the rocks as they sit within a rock core sample. The scales of the rock analysis will need to be at least ten times finer than what Curiosity can do. The rover will detect the potential biosignatures of organic compounds without grinding up the rock into a powder like Curiosity does. In addition, the rover will put the rock core samples each containing 15-16 grams of rock in a volume of about 8 cubic centimeters in a cache that could be returned to Earth in a later mission. If my measurements are correct, 8 cubic centimers is about the volume of my pinky. The cache will have slots for 38 core samples. All of the instrumentation for context and fine-scale mineralogy and fine-scale imaging and chemistry still needs to be developed. Also to be developed will be an experiment package for demonstrating how we could extract the oxygen, water, rocket fuel, and other chemicals we would need for humans to explore Mars and eventually live there from the martian soil and atmosphere. The official call for proposals will be going out nationwide and even internationally in a few months.

Eventually returning the samples to Earth will be necessary to definitively determine whether or not the sample has biologically-produced material in it because the hardware needed to rule out possible non-biological processes is over 100 times larger than what we could possibly put on a rover and way, way too sensitive to withstand the shaking of launching from Earth and landing on Mars. It sure would be nice to have those fancy tricorders of Star Trek but that's technology 200 years in the future. Having the samples on Earth also enables future generations of scientists with better analytical tools and methods to probe the samples. We're still finding out new things from the lunar samples returned by the Apollo missions over four decades ago!

The focus of martian astrobiology is to look for past life rather than current life because Mars today is probably too harsh a place for life to exist today. In the far past, it was a nicer place so we're wondering if given nice conditions, could life arise on another place in the solar system? Right now we just don't know for sure if given the raw ingredients of energy, water, and organic materials, that life will arise easily or if Earth is truly exceptional. We have a number of good reasons to believe that life of some form is out there beyond the Earth but we don't have the data. Finding out if even past life existed on Mars would be a significant breakthrough in our evidence-based knowledge of what's possible out there in the cosmos. All of our studies of Mars have shown that life is not abundant enough on Mars to warrant an expensive detector of current life but it may be possible to design the experiments in such a way that could detect current life as well as the more likely case of past life. We'll see!

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.

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

Late-July 2013 looking southwest at 9 PM

Late July 2013 looking east-southeast at 9 PM

Late July 2013 looking east-southeast at 5 AM

Kern Community College District