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17 October 2011

Astronomy Lessons from the Bad Astronomer

As you may know, I am a big astronomy fan.  I love learning about our universe, and how really insignificant we are in it.  I even have the audacity to understand that this whole vastness was in no way created for us (as some people seem to believe).  I even enjoy watching all the documentaries that present the same information over and over again on the Discovery Channel.  And I also stalk (erm, I mean follow) Dr. Phil Plait, also known as the Bad Astronomer.  Anyway, he put up a couple really amazing posts the other day, and I wanted to pass them along for your perusal.  They are just amazing entries, and really show how much we have come to learn about the universe, even if we are only marginally clever apes on our little planet all alone as far as we know (for now).

The first article I want to point you to is one that deals with evidence.  Evidence for dark matter (something we have no idea what it is, but we see the effects of).  Just plain old cool stuff here.  Here is the first entry (and scroll down for the link to the second entry):
Before I do anything else, I simply have to present this insanely cool Hubble image of the galaxy cluster MACS J1206, which lies at the mind-numbing distance of 4.5 billion light years from Earth:

[Click to enclusternate, or grab the bigger 2564 x 2328 pixel version.]

Like I said, insanely cool. The cluster has thousands of galaxies in it, and a total mass of something like a quadrillion — that’s 1,000,000,000,000,000 — times the mass of our Sun!

The image was taken as part of a program called CLASH, for Cluster Lensing And Supernova survey with Hubble. A large group of astronomers from ten different countries are observing more than two dozen such distant clusters to look for many interesting things, including exploding stars (which help us gauge the expansion rate of the Universe), very distant galaxies (to help us understand the early Universe), and to look for dark matter.

Dark matter is stuff that doesn’t emit light, but has mass. Careful observations over the years have ruled out pretty much every form of normal matter we can think of, from simple hydrogen clouds to black holes. Whatever this stuff is, it’s weird, not matter as we know it.

Okay, on to the next article.  And truth be told, I think this one is actually much cooler than the first one.  Just because it deals with so many things so far back in time that it simply boggles the mind.  Especially when you consider how much we have indeed figured out, and been able to observe.  And we continue to figure out more and more as time passes.  I keep hearing all sorts of gaps slamming shut all the time.  Sadly, it appears that too many people are deaf (and blind), and still adhere to bronze age myths passed down by illiterate goat herders...  I much prefer reality, even if it makes me small and totally insignificant.  I relish that we still strive to understand!

Astronomers have found when and how the cosmic fog was lifted

Take a look at the image displayed here [click to redshiftenate]. Every object you see there is a galaxy, a collection of billions of stars. See that one smack dab in the middle, the little red dot? The light we see from that galaxy traveled for 12.9 billion years before reaching the ESO’s Very Large Telescope in Chile. And when astronomers analyzed the light from it, and from a handful of other, similarly distant galaxies, they were able to pin down the timing of a pivotal event in the early Universe: when the cosmic fog cleared, and the Universe became transparent.

This event is called reionization, when radiation pouring out of very young galaxies flooded the Universe and stripped electrons off of their parent hydrogen atoms. An atom like this is said to be ionized. Before this time, the hydrogen gas was neutral: every proton had an electron around it. After this: zap. Ionized. This moment for the Universe was important because it changed how light flowed through space, which affects how we see it. The critical finding here is that reionization happened about 13 billion years ago, and took less time than previously thought, about 200 million years. Not only that, the culprit behind reionization may have been found: massive stars.

OK, those are the bullet points. Now let me explain in a little more detail.
CLICK HERE TO READ THE REST OF THE ARTICLE (Again, you really, really NEED to do this!).

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