Chromatic Fantasies

The Universe in all Its Wavelengths

The EMS, courtesy LASP/Univ. Colorado.
The EMS, courtesy LASP/Univ. Colorado.

I mention this a lot in my public talks in various venues: that the sky we see with our eyes isn’t the sum total of the universe that can be detected.  I’ll say it again, another way.  When you look at the night sky with your eyes, you’re only seeing the universe through a very small window of emissions.

Our eyes evolved to see essentially the “optical” wavelengths from the Sun.  But, as any astronomer worth the term knows, objects and events in the universe radiate at many different wavelengths of light. And, some of those wavelengths aren’t detectable by our eyes — at all.  You’ve probably heard of the other wavelengths of light — from gamma-ray and x-ray through ultraviolet, infrared, microwave, and radio. Every object radiates (emits or reflects) brightly in some part of the electromagnetic spectrum.

For example, the Sun gives off infrared and ultraviolet, as well as x-rays and radio emissions. That’s in addition to the optical (visible) light it emits.

Every wavelength radiated by an object tells us something about that object. You can learn about an object’s chemical composition, its temperature, its speed through space, its rotation rate, and even something about its magnetic field, all by studying the spectrum of light that it emits and/or reflects.  The procedure requires you to capture all the light you can, using whatever instruments you have that are sensitive to various wavelengths (and frequencies, in the case of radio astronomy).  The data you gather (and I’m simplifying immensely here) contains a treasure trove of information about the object.

Non-visual astronomy is complex to do, but it tells us so much more than we can ever learn by simply studying the cosmos in visible light. Nonetheless, there ARE ways we can “see” the universe in those other wavelengths, even if we don’t have radio-sensitive detectors, or infrared eyes or ultraviolet detectors or gamma-ray and x-ray instruments embedded in our bodies. Astronomers take the data from instruments sensitive to those parts of the electromagnetic spectrum and create “images” that our eyes recognize.  They aren’t necessary how the object LOOKS in those wavelengths, but they help us folks with the limited eyeballs learn more about the universe.

A screenshot of the Chromoscope. Check it out!
A screenshot of the Chromoscope. Check it out! Click to embiggen.

Which brings me to the Chromoscope.

It’s an online viewer that you can use by simply navigating over to the site created for the Royal Society Summer Science Exhibition 09 by Stuart Lowe (Jodrell Bank Centre for Astrophysics), Chris North (Cardiff University), and Robert Simpson (Cardiff University). They  made it available online and now YOU can explore the multi-wavelength sky.

The heart of the Chromoscope is a set of  public domain datasets from a number of all-sky astronomy projects. You can switch wavelengths and see for yourself how the appearance of the sky changes with each data set. There are currently seven included: gamma ray (Fermi), X-ray (ROSAT), H-alpha (WHAM), optical (DSS), infrared (IRAS), microwave (WMAP) and radio (Haslam). Head on over to the Chromoscope and explore the sky. Learn more about how scientists study the cosmos beyond our vision.

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