Bakersfield Night Sky – October 4, 2014
By Nick Strobel
This October is going to be an especially interesting month for astronomy. Tonight is the free star party with the Kern Astronomical Society at Panorama Park from 7:30 to 10 PM. We have a total lunar eclipse on October 8th followed by a partial solar eclipse on October 23rd. Comet Siding Spring (C/2013 A1) will buzz Mars on October 19th. The Orionid meteor shower peaks around October 20th to 22nd. Closer to home, I'll be teaching a course on the constellations and properties of the stars through the Levan Institute for Lifelong Learning on the Tuesdays of October. Finally, on October 16th will be the second public evening show at the William M Thomas Planetarium, Ice Worlds.
Tickets for Ice Worlds on October 16th are available at the Bakersfield College Ticket Office or online. Tickets are $8 for adults and $6 seniors and children 5 to 12 years old. The show begins with a tour of the evening sky constellations using the Goto Chronos star projector. Then we will use the Spitz SciDome to travel to the Arctic and Antarctic regions of our planet to examine the ecosystems that live and thrive there and see how their survival is connected with our own. Beyond Earth, we'll see how the existence of ice shapes the landscapes and the natural systems on other planets and moons in our solar system, including Mars, Titan, and Enceladus.
The first meeting of the Levan Institute class in the Planetarium is on October 7th. It will cover the fall constellations and an introduction to spectroscopy. When we take the light from an object and spread it out into its individual colors to make a spectrum, the brightness of the colors can tell us about the temperature of the object. If the object is made of very thin or rarefied, low density gas or layers of thin, rarefied gases, there will be a barcode pattern of lines in the spectrum. The barcode pattern that tells us the composition of the object, its temperature, and its motion along the line of sight from how much the barcode pattern was shifted. We can also get the density of the gas. So spectroscopy enables us to meaure the conditions inside an object or on the surface of an object.
The following morning before sunrise on October 8th will be a total lunar eclipse, where a Full Moon goes entirely inside the darkest part of the Earth's shadow (the umbra). For this eclipse, the Full Moon will pass through the upper (northern) part of the Earth's umbra and the Full Moon this month will be near perigee making it appear a bit larger in our sky. Therefore, totality will last just 59 minutes. (The longest total lunar eclipses are about an hour and 45 minutes long.) You will see the Moon begin to enter the Earth's umbra when it is slightly west of due South at 2:15 AM. Just above the Moon will be the Great Square of Pegasus with the two strings of Andromeda sticking out to the left. The Earth's umbra will creep across the face of the Moon from east to west (left to right). Totality will begin at 3:25 AM when the Moon will be about half-way up in the southwest sky but still next to the Great Square of Pegasus. Technically, the Moon is actually in the zodiac constellation of Pisces but Pisces is made of such dim stars that you need a nice dark sky to see its stars well. Totality lasts until 4:24 AM. The Moon will be about a third of the way up in the southwestern sky by then. After that you will see the Moon emerge from the umbra and other side of the umbra will creep across the Moon from left to right. The Moon will finally be entirely outside the Earth's umbra at 5:34 AM and the Moon will be just a fifth of the way up in the southwest. Another thing to look for during totality is the planet Uranus about two Moon diameters to the lower left of the Moon. The attached star chart below shows the early morning sky before the eclipse begins and the inset shows the particulars of the eclipse with Uranus's position at the start of the eclipse.
What color will the Moon be during totality? Although the Moon is in the umbra, there is still some sunlight that bends through the Earth's atmosphere and falls upon the Moon. The bluer colors are scattered away so just the orange and red colors reach the Moon. If the Earth's atmosphere is relatively dust free, the Moon can be a coppery orange color. A bit of dust after a major volcanic eruption can block even the red and orange colors so the Moon is dark red, even dark brown, so the Moon almost disappears. Therefore, the color of the Moon is a measure of the global air quality. Also, the outer edge of the Earth's umbra is not as dark as the very center of the umbra. Since the Full Moon is staying near the outer edge of the umbra, it should be a bit brighter than other lunar eclipses. We'll have to wait and see how much ash the volcano, Mt Ontake, in Japan puts up in the stratosphere. The stratosphere is key because once volcanic ash gets up to the lower bound of the stratosphere, the jet streams can distribute the ash around the globe.
In other astronomy news the MAVEN craft of NASA and the MOM craft from India arrived safely at Mars last week. Both will be studying Mars's atmosphere. Besides studying the upper atmosphere of Mars, MAVEN's Imagining Ultraviolet Spectrograph will make observations of Comet Siding Spring when the comet passes very close to Mars on October 19th. The spectrograph will allow us to not only derive the composition of the comet's coma (atmosphere of the comet) and tail but also to map differences in the composition throughout the coma and tail. MAVEN is the only one of the Mars orbiters that has this ability so it was quite nice of the comet to wait until MAVEN had arrived at Mars and had finished 2/3rds of its commissioning phase. MAVEN will also have time to take measurements of Mars's upper atmosphere before the comet arrives so that we can get a before and after look at atmospheric changes. The other orbiters will be able to study the dust in the coma and tail.
In one of my July columns I wrote about the possibility of the much ballyhooed proof of cosmic inflation in the very early universe was due to an early incorrect model of the effects of dust in our own galaxy. Last week the Planck mission team that is mapping the dust effects of our galaxy released a preliminary result that seems to show that the dust of our galaxy is even more likely to be what the BICEP2 team thought was the signal for cosmic inflation. More definitive conclusions should be made by December when the Planck team finishes its work on mapping the dust contamination across all microwave bands. Only after that point will we know for sure whether or not the BICEP2 team really found the proof of cosmic inflation (and get the Nobel prize in Physics).
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