Light as a Tool: Part 1

Happy Monday!

Today I’m going to tell you about spectroscopy! Spectroscopy is a very interesting technique using light as a tool. When light is used on a material- it is either scattered, emitted, or absorbed- which then tells us qualities about the material! Think about this- if you put a white light through an unknown material and the light is then scattered into a continuous (there’s no gaps) rainbow- then you know the material is a prism! 



Caption: This is why rainbows appear! Raindrops act like mini-prisms and splits the sunlight into different colors!

Caption: This is why rainbows appear! Raindrops act like mini-prisms and splits the sunlight into different colors!

But keep in mind that “light” is not just what we can see all around us. That is only a very small portion of the Electromagnetic Spectrum, which we call visible light. The EM Spectrum is ALL “light” waves: Radio, Microwave, Infrared, Visible, Ultraviolet, X-Rays, and Gamma Rays. What’s really entertaining to think about is that light still travels at the same speed no matter what- but HOW they travel is different with each wave. Radio waves are very, very long- from football field size to even building size! Gamma rays are smaller than atoms! We’ll talk about wavelengths in astronomy another day.

The infrared section of the EM Spectrum is very important to us space geologists. This is because most rocky material and gases emit or absorb infrared light. Each rocky material and gas has a unique signature- called the “fingerprint”- that we can detect and label after we collect data. We therefore make a “library”- a collection of rocks and gas fingerprints in a database that we can reference back to! But it truly is not that simple…

Gases in space do not occur in stand-alone regions in space, but rather jumbled and complex. Same with rocks, where regions on planetary bodies are not in nice orderly piles, but mixed together. This is what makes our job interesting- to figure out the puzzle pieces- what is the mystery material trying to tell us about that planetary body or even our own Solar System environment!

Did you know: New Horizons now has a new target- MU69. MU 69 is in the Kuiper Belt and is categorized as a “cold classical object.” No, that doesn’t mean it is like Stravinsky’s Rite of Spring, but rather it has never been changed (melted, broken, alien selfie spot) since the beginning of the Solar System!

Tune in next week when I continue to talk about spectroscopy of rocks and why it is sometimes a little tricky!

Caitlin Ahrens