These are infrared images from the Spitzer Space Telescope of the Andromeda Galaxy. The composite image above shows the combination of ocean wave-like galactic dust (red) which contains mostly younger stars, and the calmer, still-water sea of older stars (blue). Below are two views which separate the old from the new. As well, you can see the twisting lanes of dust that curve toward the centre of the galaxy. Normally, visible light images would show the core to be a bright, white mass of stars. Additionally, using the infrared images, astronomers were able to calculate the mass of the galaxy. A star's mass can be found by the amount of infrared light it emits. Andromeda comes in at about 110 billion times more massive than our sun, which translates to about one trillion stars. Our Milky Way is home to approximately 400 billion stars. Andromeda is the closest large galaxy to us, sitting about 2.5 million light-years away.

Image Credit: NASA/JPL/Caltech/P.Barmby, CfA

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