Some of the most breathtaking views of Earth taken from space are those that capture our planet's limb. When viewed from the side, the Earth looks like a flat circle, and the atmosphere appears like a halo around it. This edge of the atmosphere is known as the limb. Viewed from space, the image of this luminous envelope of gases shielding life on our planet from the dark, cold space beyond rarely fails to fascinate us. What makes this image even more fascinating is the added silhouette of the space shuttle Endeavour. The orange layer seen is the troposphere, where all of the weather and clouds that we typically experience are created and contained. The troposphere gives way to the whitish stratosphere and then mesosphere. This image was captured by an astronaut prior to Endeavour's rendezvous and docking with the International Space Station on February 9, 2010.