Monet’s Ultra-violet Vision

Monet's two versions of "The House Seen from the Rose Garden" show the same scene as seen through his left (normal) and right eyes.

The eye’s lens is pretty good at blocking ultra-violet light, so when Claude Monet (whose works we visited earlier this year) had the lens of his eye removed he could see a little into the ultra-violet wavelengths of light.

Monet’s story is in a free iPad book put out by the Exploratorium of San Francisco called Color Uncovered (which I have to get). Carl Zimmer has a review that includes more details about Monet and how the eye works.

↬ Joe Hanson

P.S.: All of Monet’s works can be found on WikiPaintings, a great resource for electronic copies of old paintings (that are out of copyright).

Painting the Universe: How Scientists Produce Color Images from the Hubble Space Telescope

The images taken by the Hubble Space Telescope are in black and white, but each image only captures a certain wavelength (color) of light.

The Guardian has an excellent video that explains how the images from the Hubble Space Telescope are created.

Each image from most research telescopes only capture certain, specific colors (wavelengths of light). One camera might only capture red light, another blue, and another green. These are captured in black and white, with black indicating no light and white the full intensity of light at that wavelength. Since red, blue and green are the primary colors, they can be mixed to compose the spectacular images of stars, galaxies, and the universe that NASA puts out every day.

Three galaxies. This image is a computer composite that combines the different individual colors taken by the telescope's cameras. Image from the Hubble Space Telescope via NASA.

The process looks something like this:

How images are assembled. Note that the original images don't have to be red, blue and green. They're often other wavelengths of light, like ultra-violet and infra-red, that are not visible to the eye but are common in space. So the images that you see from NASA are not necessarily what these things would look like if you could see them with the naked eye.

NASA’s image of the day is always worth a look.

How to Watch a Meteor Shower

A meteor shoots past the Milky Way. Image by L.Brumm Photography and Design.

Space.com has an excellent guide about the best way to observe meteor showers; dress warm; after midnight; be patient). The Lyrid meteor shower is on this week.

To take good photos of a shower you’ll need to do long exposures or get lucky. Details on the photo above here.

On the Loss of Boredom in the Internet Age

I remember, as a child, being bored. I grew up in a particularly boring place and so I was bored pretty frequently. But when the Internet came along it was like, “That’s it for being bored! Thank God! ….”

It was only later that I realized the value of being bored was actually pretty high. Being bored is a kind of diagnostic for the gap between what you might be interested in and your current environment. But now it is an act of significant discipline to say, “I’m going to stare out the window. I’m going to schedule some time to stare out the window.”

— Clay Shirky in an interview with Sonia Saraiya on Findings.com

We need a little boredom, to let our minds wander and thus to spur creativity.

Zoë Pollock, on The Dish, highlights the thoughts of Clay Shirky and the response of Nicholas Carr on loss of space for boredom in the internet age.

History of the Atmosphere (from the Formation of the Earth)

Composition of the atmosphere from the formation of the Earth. Image ᔥJoel Cayford ↬Ethan Siegal

Joel Cayford has posted a nice image showing the composition of the atmosphere over time — since the formation of the Earth.

Note that, although the Earth is 4.5 billion years old, and life has been around for over 4 billion years, there has only been oxygen in the atmosphere for about 2 billion years.

Oxygen is an extremely reactive gas, which is why we use it when we “burn” carbohydrates for energy. But it also means that any free oxygen added to the atmosphere would easily react with rocks, water, and other gasses in the atmosphere, so would not be available in the quantities needed for air breathing organisms until it slowly accumulated.

Also, you need a lot of oxygen in the atmosphere to produce enough ozone to form the ozone layer that protects life at the surface from high-energy, cancer-inducing, ultra-violet radiation from the Sun.

Generating (and Saving) Tones with SoX

I’ve been using the command line program SoX to generate tones for my physics demonstrations on sound waves.

Single frequency tones can be used for talking about frequency and wavelength, as well as discussing octaves.

Combine two tones allows you to talk about interference and beats.

SoX can do a lot more than this, so I though I’d compile what I’m using it for in a single, reference post. For the record: I’m using SoX in Terminal on a Mac.

Using SoX

To play a single note (frequency 173.5 Hz) for 5 seconds, use:

> play -n  synth 5 sin 347

To save the note to a mp3 file (called note.mp3) use:

> sox -n note.mp3 synth 5 sin 347

The SoX command to play two notes with frequencies of 347 and 357 Hz is:

> play -n synth 15 sin 347 sin 357

and to make an mp3 file use:

> sox -n beat_10.mp3 synth 15 sin 347 sin 357