Lightening bugs lost in light pollution

This evening I’m going avoid saying anything too profound or educational. My evening was spent eating grilled foods, and drinking things I’m sure weren’t healthy as I kicked back with many of the other faculty and their spouses. There is a magical hour here in our middle-class suburban existence when the fireflies begin to flicker in the grass and the stars and planets begin to spring out of the sky. In the cities where I have lived for most of my adult life this magical hour was missing – the stars and the bugs had both been consumed by the cement and illumination of urban existence.

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Cosmic Backlighting: The Cosmic Microwave Background

Cosmic Backlighting: The Cosmic Microwave Background

Cosmic Microwave BackgroundThis is the second part in what I had originally seen as a two part series on what may be the neatest tools in astronomy’s tool belt for indirectly examining the stuff of the universe. I say originally thought, because as I sit here writing, I’m thinking this is going to evolve into three parts. In this entry I want to address where is CMB came from and how it tells us where we’re going. (image credit: NASA / WMAP Science Team)

Pick up pretty much any astronomy text, look up Cosmic Microwave Background, and you’ll find something along the lines of: “The Cosmic Microwave Background is a relic of the moment the universe cooled enough for recombination to take place. Prior to that moment the universe was opaque to radiation. Today we see this left over radiation as a 2.725 K degree microwave background radiation.” The book will then go onto explain how the CMB was detected.

Did any of that make sense to you? I know it didn’t make sense to me the first dozen or so times I read it over the years. Let me see if I can make sense of this scientific obstruction for you.

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9th Carnival of Space

The 9th Carnival of Space is up at the Planetary Societ Weblog, which is written by Emily Lakdawalla.

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All your words

I just want to drop you, my gentle readers, a message to say that yes, I do read all your comments. Sometimes (like this week), I get frustrated that I don’t have the time to respond to all of you. I want to write in response to all your emails, but doing everything is sometimes an impossible balancing act.

If you don’t read PhD Comics, at least check out their latest comic. For me it is currently a careful balance of writing this blog, Astronomy Cast, writing grants, doing research, answering email/comments, being married, and trying to keep up with our 110 year old house. Wheeeeee
Most days I love my life, but all days I feel like I’m behind in everything I want to do. There simply aren’t enough hours in the day. Sometimes, what I end up actually being behind in doing is writing answers to comments from you.
But I always read all your comments…

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Gravitational Lenses: Making the invisible detectable

Gravitational Lenses: Making the invisible detectable

Diagram of Gravitational LensingAstronomers on Earth are limited in how they can look at the universe. We basically have three tools. We can detect light across a broad spectrum of colors. We can capture high energy particles – cosmic rays – that are flung at us from distant events. We can also potentially measure gravity waves (but we’re still sorting out that technology). In all three instances, we are limited by our technology’s sensitivity to an event. This means that faint, small, low energy stuff at any significant distance is invisible as far as our detectors are concerned. And stuff like dark matter… well… it can’t be directly detected at all. When direct detection of something is impossible, it becomes necessary to find indirect methods. We are like Plato, looking to understand reality but only able to see shadows dancing on a cave wall.

Two of the most well defined ways we have of studying the universe’s shadows are the Cosmic Microwave Background (CMB) and gravitational lenses. Both things are scientifically interesting in their own right, and each can be used to indirectly see otherwise invisible content in the universe. Recent papers have shown how the CMB may allow astronomers to study our own solar system’s Oort Cloud (the source of long period comets), and how gravitational lensing effects can be used to map dark matter. Rather than try and discuss both these topics in one post, I’m going to take on gravitational lenses today, and dig into the cosmic microwave background tomorrow. (image credit: Kneib & Ellis w/ Caltech Digital Media Center)

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