Cosmological Principle

        I went for my evening walk listening to an astronomy lecture on “Homogeneity” which has to do with the Cosmological Principle, and how the universe is both Isotropic and Homogeneous. Isotropy is the uniformity of the universe in all directions that we look. Homogeneous is the composition of matter spread out in a very large area, is the same everywhere; the larger the area you view the more Homogeneous it becomes, the smaller the area you view the less Homogeneous it is (this is a tough one to understand). Okay, let’s try this: If you spill a pound of salt thinly and evenly on a large floor and you look at it very closely you would see the individual grains, but if you stand at a distance all you will see is a white flat surface. The Cosmological Principle is what scientists use in their mathematical models of the universe and the beginnings of the Big Bang.        There was one part that was of interest to me when they talked about after the Big Bang, how was it that matter was able to “talk” to each other so that matter would be the same everywhere. They said this was due to Cosmic Inflation, but they also said that there are other theories, one being that light could travel faster early on in the Big Bang; I’ll have to read up on this because it kind of goes along on my thinking about Black Holes shrinking, where matter is squeezed to a point that it loses space time and that exotic particles can exceed the speed of light and escape from a singularity. (Of course this is my imagination exceeding the limits of my knowledge)

Molecules in Space

        Went for my evening walk re-listening to the astronomy lecture on “Molecules in Space”. In the very early universe free protons flew around at very high energies and temperatures hitting each other and sometimes bonding to form molecular hydrogen (two protons: H2) which would cool down. Once enough molecular hydrogen was created and cooling down the universe to several thousand degrees, the first stars, hundred times larger than the Sun, could form. These massive stars had a lifespan of a million years or so until they went supernova creating heavier elements and cooling down the universe to a point where stars wouldn’t ever be that massive again. At least that’s how I understood it.

Moon Dog

From Bob's Stuff

Thursday December 11- The Moon was full and really bright and I saw something I’ve never seen before (from Wikipedia): “A moon dog or moondog (scientific name paraselene, plural paraselenae, i.e. "beside the moon") is a relatively rare bright circular spot on a lunar halo caused by the refraction of moonlight by hexagonal-plate-shaped ice crystals in cirrus or cirrostratus clouds. Moondogs appear to the left and right of the moon approximately 22° away. They are exactly analogous to sun dogs, but are somewhat rarer because in order to be produced the moon must be bright and therefore full or nearly full. While a moondog may be brightly colored, the lunar halos they form in typically appear colorless to the naked eye because their light is not bright enough to activate the color photoreceptors in humans." Well the one I saw HAD color like a rainbow, and I tried to photograph it but it didn’t come out as bright as I could visually see it, but I got it! Just click on the image that I uploaded to get a better view. Like I mentioned last night in my journal this full Moon would be the brightest of the year.

Lives of Other Stars II

        I went on my evening walk and re-listened to “Live of Other Stars” Podcast. I was especially interested in Mass Loss of stars and one class of star, the Wolf-Rayet, have over 20 solar masses, are very hot, and their stellar winds exceed of 1000 MPH which eject a lot of matter giving it a high rate of Mass Loss. If you remember that large stars, with over five solar masses, Mass Loss plays an important role in determining if the star will become a Neutron star, a Black Hole, or even (some believe) a white dwarf. So there is more to this transition to a Neutron star, a Black Hole, or a white dwarf than I was led to believe. And it isn’t set in stone depending on just how massive a star is.

Lives of Other Stars

        I went for my evening walk re-listening to the lecture on “Lives of Other Stars”. Smaller stars with 0.26 solar masses, our Sun is one solar mass, use convection unlike larger star’s Radiative Transport , and mixes the hydrogen in their atmospheres like a lava lamp which causes these small stars to burn all their hydrogen efficiently into helium and are not hot enough to burn helium (what is called helium flash). Their life span can be over 100 billion years and bypasses the red giant stage and goes right to being a white dwarf with a helium core. Stars one and a half time larger than on solar mass also use convection and smoothly transitions to burn heavier elements. Stars with over five solar masses, depending on Mass Loss, go supernova turning into Neutron Stars or Black Holes. Depending on how large a star determines what elements the star eventually burns, the degenerate gas pressure which holds the core from collapsing, and what element ignites a supernova. Population three stars were the first stars to ever form, with over 250 solar masses, and used proton/proton chain reactions to fuse hydrogen into helium to form the first heavier elements. These stars had a life of a few million years and enriched the early universe with these first heavy elements so that smaller stars could form.

Nebulas

        I went for my evening walk and listened to astronomy lecture on Nebulas. A Nebula is interstellar dust consisting of hydrogen, helium, and other trace elements. Nebulas are formed by dying stars that blow out their atmospheres; from Red Giants or Supernovas. New stars are born in Nebulas. There are two kinds of nebula: reflecting and emission. A Reflecting Nebula reflects light from a nearby bright star, and its color is blue. An Emission Nebula is usually the process of new stars being born within and the light from these stars or protostars excites electrons in atoms of the Nebula to higher energies to emit photons. Emission Nebulas are red in color.

        My friend Kula called to ask about the Leonid Meteor Shower that peaks on the 17th and 18th of this month. I told her that the Moon would probably washout any meteors and the smoke from the fires would be another obstacle. I’m not going to bother with this one but I might go out to take a peak just in case!

Life Cycle of the Sun

        Went on my evening walk and listened to an astronomy lecture about the life cycle of our Sun. To make a long story short it will go through a few phases after it falls off the main sequence five billion years from now; burn most of its hydrogen fuel as its diameter expands to form a Red Giant. Helium replaces hydrogen in the core. Hydrogen still fuses a layer around the core as it condenses and heats up. At 100 million Kelvin helium starts to burn in the core producing carbon and oxygen. While all this is happening the outer layers are being breathed out forming a planetary nebula. When all the helium is turned into carbon, the core collapses down into a White Dwarf with electrons packed tightly together (what is called electron degeneracy). Basically a White Dwarf is a diamond and does not fuse matter but shines under its stored heat.