By Bill Pellerin

Houston Astronomical Society

GuideStar Editor

When you look at the sky, what do you see? On a clear night, you’ll see stars, perhaps the moon, perhaps one or more planets. Do you ever see clouds in space? They’re a bit harder to see than many of the bright objects, but they are often the most interesting objects in the sky. These objects are generally called nebulae (the plural of nebula) and the word ‘nebula’ is from a Latin word meaning ‘cloud’. They don’t look like small points of light; they look hazy and, well, cloudy. For a long time, we didn’t know what these objects were, but now we do. If you listen, you’ll often hear observers say that an object is ‘non-stellar’ – meaning that it is not a star – meaning that it is nebulous.

Let’s begin with a bit of history.

One of the kinds of nebulae seen by early observers was a spiral nebula. One of the first observers to see these spiral nebulae was a British fellow named William Parsons, the 3^rd Earl of Rosse. In 1845, he built a very large telescope – called the Leviathian. With this telescope, he saw the spiral structure of M51, the object we now know as the Whirlpool Galaxy. In 1889, Vincent Van Gogh painted the famous ‘Starry Night’ which includes a spiral shape in the sky thought to be inspired by the drawing of Lord Rosse.

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