Activity created by Angela Damery, Exhibit Hall Interpreters, Museum of Science, Boston
Okay, so satellites use near infrared to see some interesting things from space,
but real people don't use it.
Or do we?
Take a look at black clothes in near infrared light, and see if you see a difference.
Not all black cloth is created equal, at least in the near infrared. The fabric that is dark, in either the visible or near infrared images above, it is absorbing most of that light falling on it (reflecting very little). Remember, light is energy, and if an object is absorbing light, it is gaining energy which will either drive a chemical reaction (photosynthesis, for example) or the object will warm up. Roughly 50% of the Sun's light is emitted in the infrared (with most in the near infrared), so if your clothing is absorbing this light, you are gaining a great deal of energy to warm up.
The sport clothing industry knows to use fabrics that reflect the near infrared – take a look at pictures of this visiting baseball team. Visiting teams wear their dark colors, and during the summer, if these uniforms absorbed near infrared, the players would get quite warm, adding to the home field advantage.
Conduct Your Own Investigations
Explore materials that interest you to see what is more likely to heat up in the sunlight – your wardrobe (including light-colored clothing), hair, animal fur, building materials (bricks, cement, wood, asphalt, etc.), natural land cover materials (dirt, rock, water, leaves, etc.).
Modified digital camera that sees in the near infrared
Thermometer (preferably a thermal infrared type which doesn't require touching the surface to measure temperature)
Light source - sun or bright light
See equipment source page
- Measure temperature of object in shade
- Turn on light or expose to sunlight
- Begin measuring temperature every 10-30 seconds
- Measure until temperature stops rising
- Move object into shade or turn off light
- Measure how quickly the object cools
See examples of seeing unexpected results in the near infrared.