APOD 2.3

NGC 7023: The Iris Nebula (November 12, 2010)

This picture shows the Iris Nebula, which is located in the constellation Cepheus. It is named the Iris Nebula because of its resemblance to flowers. The center of the "flower" is a bright shining light, surrounded by blue petals. The center is actually a hot, young star, and the blueish colors come from the scattering of white light off dust particles that survived the stars birth. This scattering is similar to Rayleigh scattering, which is responsible for the color of the sky on Earth. This also explains why the Iris Nebula is a reflection nebula versus an emission nebula. Reflection nebulae because they cannot create their own light and scatters the light of other stars nearby. Emission nebulae are clouds of hot gas that are hot enough to emit light themselves. This APOD was interesting because I was not aware of the different types of nebulae and I did not know that some nebulae could not create light themselves. I thought all nebulae created their own light. It was also interesting to read about the experiment in "The Feynman Lectures On Physics" which explained in detail why the scattering of light created the blue color we see.