Bakersfield Night Sky – April 5, 2014
By Nick Strobel
Astronomy Day is next Saturday. This free event sponsored by Kern Astronomical Society will take place on April 12th at the new Houchin Community Blood Bank at 11515 Bolthouse Drive (off of Buena Vista Rd between White Lane and Panama Lane). On Monday there will be a Solar Social from 4 to 7 PM with pizza and snacks and observing the Sun with the KAS solar telescopes to kick off Astronomy Week in the buildup to the full day of astronomy workshops and speakers, including Alex Filippenko and Terry Himes on Saturday. More information about Astronomy Day and fliers for downloading are posted on the Astronomy Day site at kernastro.org/astroday .
The following week in the very early hours of April 15th we will get to experience a total lunar eclipse. (No, this has nothing to do with it being tax day.) A total lunar eclipse happens when the Full Moon goes through the Earth's umbra shadow. The umbra shadow is the region in which the light source would be totally blocked, so it is the darkest part of a shadow. For this eclipse the Moon will go through the southern part of the Earth's umbra. The inset of the attached star chart shows the particulars of this eclipse. The umbral part of the eclipse begins at 10:58 PM our time on April 14th and totality goes from 12:07 AM to 1:24 AM on April 15th. The Moon will leave the umbra at 2:33 AM. Although the Moon will be in the darkest part of the Earth's shadow, the Moon will have a reddish color as sunlight bends through the Earth's atmosphere to reach the Moon and the bluer colors in the sunlight are scattered away. I have diagrams describing lunar eclipses and photos of eclipses in my online astronomy book at www.astronomynotes.com/nakedeye/s14.htm .
One event we seemed to have detected directly for the first time is the super-rapid accelerated expansion of the universe in the first 10-36 second after the Big Bang. That's a trillionth of trillionth of a trillionth of a second! This super-rapid expansion is called "cosmological inflation" or just "inflation" if the context is clear that you're talking about cosmology and not about economics. Inflation was an idea invented by Alan Guth in 1981 and further developed by Andrei Linde and others in the following years. Inflation was invented to explain two problems with the classical Big Bang theory called "the horizon problem" and "the flatness problem".
The horizon problem is that various parts of the cosmic microwave background are so similar to each other when they shouldn't be that way. The cosmic microwave background is leftover radiation from the early history of the universe when the universe had cooled sufficiently enough for protons and electrons (and neutrons) to get together to form atoms for the first time. Back then, about 380,000 years after the Big Bang, the universe was about 3000 Kelvin and the universe was glowing in the red and infrared. Since then, over the past 13.8 billion years, the universe has expanded by a factor of a thousand and the universe has cooled to just 3 Kelvin (that's three degrees above absolute zero) and the universe glows in the microwave band. Now consider the light coming from opposite directions of the cosmic microwave background. Those regions of the early universe should not have had time for the temperature, density, etc. to have equilibrated with each other by sharing information back and forth at the speed of light. Those regions would have been beyond each other's "horizons" or causal contact with each other at that early time. A more detailed calculation of that horizon problem shows that even regions as close as one or two degrees from each other on the microwave background should be very different from each other. Instead what we find is those regions are remarkably very similar (the temperature to within one part in 100,000).
The flatness problem is that the large-scale spatial curvature of the universe is zero or "flat", or so nearly so that we can't detect any deviation from that flat condition. Of all the possibilities from very positively-curved (very high density) to very negatively-curved (very low density), the current nearly flat condition is definitely a special case. The balance would need to have been even finer nearer the time of the Big Bang because any deviation from perfect balance gets magnified over time. If the curvature of the universe was just a few percent off from perfect flatness within a few seconds after the Big Bang, the universe would have either re-collapsed before fusion ever began or the universe would have expanded so much that it would seem to be devoid of matter. It appears that the density/curvature was very finely tuned.
The horizon problem is solved by inflation because regions that appear to be isolated from each other were in contact with each other before the inflation period. They came into equilibrium before inflation expanded them far away from each other. Another bonus is that the Grand Unified Theories that predict inflation expansion also predict an asymmetry between matter and antimatter, so that there should be an excess of matter over antimatter, just like we observe in the universe today. The inflation theory also predicts that the ultra-fast inflation would have expanded away any large-scale curvature of the part of the universe we can detect. It is analogous to taking a small globe and expanding it to the size of the Earth. The globe is still curved but the local piece you would see would appear to be fairly flat. The small universe inflated by a large amount (by a factor of 1050!) and the part of the universe you can observe appears to be nearly flat. That solves the flatness problem.
The inflation theory also says the ripples in the microwave background are the super-stretched quantum fluctuations in the early universe. The super-rapid growth of the universe during inflation would have stretched the fluctuations to much larger sizes---large enough to create the ripples in the microwave background that eventually became enhanced to form galaxies under the action of gravity over billions of years. Although the current versions of inflation theory cannot answer all of the questions about the large-scale structures of our universe, they do predict a particular distribution of the ripple sizes in the microwave background that is consistent with the results from the high-altitude balloon experiments, and the WMAP and Planck space missions. Diagrams of the flatness problem, the horizon problem, and how inflation explains them are available in the cosmology chapter of my online Astronomy Notes book at www.astronomynotes.com/cosmolgy/s12.htm .
For the past several years, astronomers have been looking for signatures of how the early universe photons scattered off the electrons just before the electrons and protons combined to make the first atoms. Scattering causes light to become preferentially oriented in a particular way (it is "polarized"). The simplest version of inflation predicts a particular polarization of the microwave background. The particular polarization would arise from gravitational waves produced in that first trillionth-trillionth-trillionth of a second of inflation.
The field that is responsible for inflation would have interacted with the gravitational field of the early universe and expanded any quantum fluctuations in the gravitational field to huge sizes. Those fluctuations in the gravitational field would be gravitational waves. Those gravitational waves would produce a specific type of polarization in the cosmic microwave background. The polarization of the cosmic microwave background from the gravitational waves would provide the strongest proof of inflation we could have because there were other possible ways to explain the flat curvature and density fluctuations in the cosmic microwave background even before the inflation theory was proposed.
Gravitational waves from the time of inflation are unique to the theory of inflation so we're looking to see if we can detect those gravitational waves in the cosmic microwave background. Scientists working on the Background Imaging of Cosmic Extragalactic Polarization 2 (BICEP2) experiment at the South Pole might have spotted that signature of the gravitational waves. Their observations need to be confirmed by other research teams before we can be sure the BICEP2 team didn't make a mistake. Peer review is a critical part of the scientific process to make sure we don't fool ourselves with our pre-conceived ideas.
One other exciting piece of astronomy news has been about a small scattered disk object discovered in 2012 called 2012 VP113. The "scattered disk" is a sort of transition zone between the Kuiper Belt where Pluto resides and the very distance and large Oort Cloud of comets. Other scattered disk objects include Eris, Sedna, and Comet Hale Bopp. What is causing the buzz about VP113 is the determination that the closest approach of its orbit, the perihelion, is aligned like that of Sedna and some other far-flung objects. The similarity of that part of their orbits has led some astronomers to speculate about the existence of a large planet as big as the Earth or larger "super-Earth" orbiting about 250 AU from the Sun (that's about six times farther than Pluto's orbit). A large planet like that could have nudged these smaller scattered disk objects into similar sort of orbits. Well, speculation of a big planet like that is sure to capture the attention of the mainline media as well as purveyors of doomsday predictions and NASA cover-ups.
A super-Earth that far out from the Sun would not be detectable with current infrared telescopes. Something like the upcoming James Webb Space Telescope might be able to image it if we knew right where to look. I'm a bit skeptical about the existence of this super-Earth. The authors of the paper describing the orbit of VP113 also note that the super-Earth is just at the "suggestive stage." A lot more observations need to be done to strengthen the case for this proposed object beyond the mere speculative, suggestive status it currently has.
In tonight's night sky, Jupiter will be high up in the south just after sunset between the two string of stars that make up the Gemini twins. Brighter than any star in our night sky, Jupiter will be the first star-like object you see after sunset. It is bright enough that you'll still be able to see it easily even with the fat Waxing Crescent Moon nearby at the feet of the Gemini twin, Castor. The attached star chart shows the sky at 9 PM and where the Moon will be between tonight and the night of the Full Moon for the eclipse. The Moon will be at First Quarter phase tomorrow. On Tuesday, April 8th, the Waxing Gibbous Moon will be below the Beehive Cluster in Cancer. April 10th the gibbous Moon will be below Regulus at the bottom of the Sickle part of Leo. On April 13th, the bright gibbous Moon will be next to orange-red Mars in the middle of Virgo. Mars is visible by 8 PM and should be bright enough to see even when the Moon is close to it on the 13th. Jupiter, Mars, and the Moon will be targets to observe with the KAS telescopes on Astronomy Day. On the night of the total lunar eclipse, April 14th, the Full Moon will be just above the bright star Spica on the eastern side of Virgo. April 14th is also when we will be closest to Mars as we move past it in our faster, inner orbit.
Saturn becomes visible at around 10:30 PM tonight and by the night of the eclipse, it should be visible shortly after 10 PM. Your distance from the mountains in the east will determine when you first see it rising in the east with the stars of Libra. In the pre-dawn morning, you'll see bright Venus low in the east an hour before sunrise. The Waning Crescent Moon will be next to Venus the mornings of April 25th and 26th.
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