Preview: What You Will See

The Messier Catalog is a listing of more than 100 celestial objects compiled in the 1770s by French astronomer Charles Messier. The Messier objects are some of the most beautiful and well-known objects in the night sky. The catalog was assembled so that comet-hunters would not mistake a diffuse (fuzzy) new comet discovery with one of these cataloged objects. The Messier catalog includes a wide range of phenomena, including star clusters, nebulae, and the island universes we have come to know as galaxies. The Gallery includes a representative cross-section of objects in the Messier catalog.

Each gallery is devoted to a single object, and includes up to nine images taken at different wavelengths. All images are oriented such that north is to the top and east is to the left, following standard astronomical conventions. Within a given gallery, each image size is identical; that is, they have the same angular scale. The image size is indicated at the top of each gallery page, and is expressed in units of arcminutes. [An arcminute, abbreviated "arcmin", is 1/60th of a degree, where 360 degrees comprises a full circle.] For a convenient point of reference, note that the full moon is about half a degree (or 30 arcmin) across. When comparing images within a gallery, be sure to keep the image size and orientation in mind.

Descriptions of the astronomical telescope, observatory, or survey used to obtain each image are available by clicking on the image caption. Note that different false-color schemes are applied to each of the images. In general, the brighter colors (white, red, yellow) denote brighter regions of emission; darker colors (black, violet, blue) represent weaker emission, and occasionally represent random detector noise and celestial sky background.