Last ADYK we discussed extinction due to clouds of dust and gas in outer space. When we view objects like the pillars of creation in visible light, the stars are blocked by the pillars of clouds. To beat the extinction, astronomers look at the infrared light coming from that region, which is able to pierce through the clouds revealing the hidden stars! Infrared light has a longer wavelength, so it's able to travel further and through more material before it gets absorbed or scattered. This is because most of the gas and dust particles are smaller that the wavelength of infrared light. The concept is similar to that of radio waves. We use radio waves on Earth to transmit information because the wavelengths are very long, on the order of meters. So for the radio waves, things like people, buildings and trees appear "small" or on about the same size scale as the waves are. Therefore, the waves can travel pretty far before they are disrupted. Shorter waves, like millimeter long waves, wouldn’t travel very far on Earth because they are smaller than the objects they must travel past. Going back to our pillars of creation, infrared waves emitted by the stars are longer than the size of the gas and dust, thus the light can travel through the clouds. The picture above is taken in infrared light, and we can now see all the stars that were previously hidden behind the clouds!
Image Credit: ESO/VLT
