How to See a Nebula

Types of Nebulae

• 1

  Surround a star with dust positioned so that it reflects the light of the star. This is called a reflection nebula. The nebula that surrounds the stars of the Pleiades in the constellation Taurus is the best-known example of a reflection nebula.

• 2

  Position a star inside a cloud of dust and gas that shifts the star's color to a longer wavelength of light or cuts it off entirely. This is called a dark nebula; you can see where it is by the stars surrounding it that it doesn't obscure. The Coalsack Nebula in the constellation Sagittarius is the best-known example of a dark nebula.

• 3

  Slough off layers of gas from a dying star so that they surround it in a donut-like shape that orbits the star. This is called a planetary nebula. The Ring Nebula in the constellation Lyra is an example of a planetary nebula.

• 4

  Ionize the gas surrounding a star so that it gives off light of its own. This is called an emission nebula. Emission nebulae are often found around protostars and hot, blue stars. The Great Nebula in the constellation Orion is an example of an emission nebula.

Seeing a Nebula

• 5

  Consult a star chart or list of stellar objects, such as the Messier catalog compiled by Charles Messier or the New General Catalog, begun by Sir William Herschel.

• 6

  Focus your telescope at the coordinates given for the object in the catalog.

• 7

  Look through the eyepiece for a quick glance at the nebula. You will not see the nebula in color this way, as it requires a time-lapse exposure for the colors to be visible.

• 8

  Attach a camera to the eyepiece, set for long-term exposure.

• 9

  Set the telescope's motor to follow the position of the nebula across the sky during the time of the camera's exposure.

• 10

  Remove the camera when the telescope stops moving and process the film. You should see an image of the nebula in color, the longer the exposure, the more vivid the colors.

• 11

  Compare the observed color of any star in a nebula with its spectral lines recorded in a mass spectrometer. Each star gives off distinctive spectral lines according to its temperature. If the star's color is of a longer wavelength than its spectral lines say it should be, the star is surrounded by interstellar dust.