Free data set of the month: Imaging Spectroscopy

There's a lot of free data sets floating around the internet, and while things like funny cat videos and the results of color-naming surveys get a lot of play, many others don't get used for much. Recently I've been playing around with one such data set: images from the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS).

I've always found it interesting that the way we perceive color is very different from how light actually works. Most of us have three different types of cones in our eyes and we perceive different colors as different combinations of stimuli to these three types of cones. In a very rough sense, when we look at a color, our brain gets three different numbers to figure out what it is. Light, on the other hand, is a bunch of photons with some distribution of wavelengths. To fully describe the light coming from an object you need a function that shows how many photons are at any given wavelength, which is way more complicated than just the three numbers we get.

So what about all that information that gets thrown away on the way to our brain? Are we missing out on a magical world of super-duper colors and wonder? Not really, but skip past the break anyways to find out more.

Freezing in Space II - Turn On The Sun!

Yesterday I considered how long it would take a human to freeze in space.  However, I considered only what would happen if you were not absorbing any radiation from nearby sources.  Today we consider what happens if you do have hot objects nearby.  Namely, the sun.  The sun provides a lot of energy, even as far away from it as we are.  It keeps the earth at a comfortable ~20 C, good for us humans, and provides the energy for life on earth, also good for us humans.  That's a lot of energy.  So maybe the sun can keep you alive when you're adrift in space.  Or at least keep you warm.  I still think you'll asphyxiate.

Freezing in Space I - Blackest Night

In the last post I made, I discussed the fact that humans radiate energy.  In that post I calculated that we actually radiate quite a lot of power.  This immediately raises a few questions, the most obvious one being: How long would it take you to freeze in space?  This question is multifaceted, and I'm going to split it between two parts.  This first part, 'Blackest Night' is how quickly we'd freeze if we were completely lost in space, nothing anywhere near.  The second part, 'Turn On The Sun!' will address what would happen in near earth orbit.

Human Radiation

Things are still busy here at the Virutosi.  Hopefully in a week or so we'll be back to normal, and much more active than we've been recently  Anyways, today I'd like to consider human radiation.  It is well known that any object will radiate energy based on its temperature.  Even more interesting, we radiate at all wavelengths, though at the human body temperature our radiation is sharply peaked in the infrared.  Even so, we still put out some x-ray radiation.  As a professor of mine once said, consider that next time you sleep with someone!  Given all this, the question on my mind today is:  how does the energy we radiate daily compare to the energy we consume?  That is, why don't I lose weight sitting here typing on the computer?