Bakersfield Night Sky – July 18, 2015
By Nick Strobel
Next Saturday, July 25th, is the free public star party hosted by the Kern Astronomical Society at Panorama Park from 8 to 10 PM at Panorama Park near where Linden Ave runs into Panorama Drive. The Moon, Venus, and Saturn will be bright targets to see along with beautiful star clusters and nebulae. Observing will start soon after sunset and go to about 10 PM, depending on foot traffic.
This evening sky shows a beautiful grouping of a thin Waxing Crescent Moon just below a dazzling Venus with Jupiter and the bright star, Regulus, less than a fist width at arm's length away as shown in the first star chart below. Definitely photo worthy! (Select the image below to view a higher resolution version without the labels.) Look for them low in the western sky shortly after sunset. Through a telescope you will see that Venus is also in a crescent phase in the same orientation as the crescent Moon but this crescent is going to get thinner as Venus continues to get closer to us in its faster orbit around the Sun. Tonight Venus is 19% lit and next Saturday at the free public KAS star party it will be 13% lit. By the end of the month it will be a very thin 7% lit crescent.
Since the very close conjunction of Venus and Jupiter at the end of June, Venus and Jupiter have been moving farther apart in our sky. On this coming Thursday, July 23rd, Venus will start moving westward with respect to the stars and it will pass by Jupiter again at the end of July. However, Venus is looping southward, so it will pass far below Jupiter in our sky.
Saturn is nicely placed in the southern sky in the evening. It is still among the stars of Libra, a bit to the right (west) of the brighter stars of Scorpius. Saturn is going to get slightly dimmer from here on out but the rings will still be spectacular in a telescope such as the KAS telescopes at the free public star party next Saturday even with a bright Waxing Gibbous Moon nearby.
Those with Pluto fever after the New Horizons flyby can try finding it among the dimmer stars of Sagittarius. It is to the upper left of the Teapot part of Sagittarius in a section sometimes called the "Teaspoon". The second star chart below shows its location. However, you'll need a telescope over 12 inches in diameter to even have a chance of spotting it. But one wonders why it was so hard to find in the first place. The discovery photographs of it back in 1930 have a big fat arrow pointing to it, so couldn't they have used that arrow to locate it? :)
You all have an advantage over me because as I write this, the New Horizons flyby of Pluto is still in the future but it will have already happened by the time you read this. You'll know whether everything worked as planned. My previous column gave all of the details of the encounter on the 14th and when we will receive the data. On July 10th, the New Horizons team released a pre-encounter image with enough resolution to see geological features on Pluto. The image shows a band of polygonal features stretching about 1000 miles east-northeast near the equator and a complex region where bright terrains meet the much darker patch nicknamed the Whale because of its shape.
One interesting story that came in my newsfeed about Pluto is the several other NASA spacecraft that will be observing Pluto during the encounter and the few months after encounter. The Cassini spacecraft orbiting Saturn (still going strong after more than a decade at Saturn) will image Pluto. Starting on July 23rd, the Spitzer Space Telescope will begin a 7-day run observing Pluto in the infrared band to study the ice on the surface and search for other materials not yet identified. In October, the Kepler spacecraft will begin a three-month observing session of Pluto and Charon to learn more about the effects on their atmospheres and surfaces as they move farther from the Sun in elliptical orbits.
At the end of June, the SOFIA airborne observatory, an infrared telescope installed on a 747 aircraft, flew into the perfect position to see Pluto pass in front of a distant star. That enabled us to get data that will help us understand the density and structure of Pluto's atmosphere. Combining this data with what New Horizons will see up close just a few weeks later will greatly enhance future analyses of Pluto as SOFIA observes it in the years to come.
And then there's the Hubble Space Telescope which up to just three months ago was providing the sharpest views of Pluto since 1990. Hubble found four tiny moons (Nix, Hydra, Kerberos, and Styx) just a few years ago. Using Hubble, astronomers were able to determine that Nix and Hydra are tumbling chaotically along their orbits as they respond to the shifting gravity fields of Pluto and Charon.
One last astronomy news item is about an entirely different topic: the possible detection of the first generation of stars in the universe. In the early universe, the only elements that existed were hydrogen and helium along with traces of lithium and beryllium. All of the other elements were produced in the stars through the process of nuclear fusion. When stars die, the heavier elements (carbon, oxygen, silicon, iron, etc.) are disbursed into the surrounding space with supernovae being the most efficient way to "pollute" the surrounding gas clouds. The very first generation of stars would have been made of just the pristine hydrogen and helium gas. In the peculiar naming scheme of historical astronomy, these first generation stars are called "Population III" stars. Second generation stars, called "Population II" stars, have traces of the heavier elements in them. In our galaxy, the Population II stars are found in the stellar halo and bulge of the Galaxy. Stars like our Sun are called "Population I" stars and reside in the disk part of the Milky Way.
Up to now, the first generation Population III stars were just hypothetical. An international team headed by David Sobral might have detected Population III in a distant galaxy called "CR7". Because CR7 is very distant, we are seeing it as it was long ago when the universe was very young. The spectra of a section of the galaxy shows just hydrogen and helium without any heavier elements. However, the spectra of another section of CR7 shows stars with traces of the heavier elements, so the Population III discovery is still tentative. If the discovery pans out, it'll be a big deal in astronomy research because we have been looking for those first generation stars for many decades.
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