March's icy Milky Way is a deep-sky observer's paradise. Splashy open clusters, huge emission nebulae, and numerous planetary nebulae await the telescope. Many of the best-known planetary nebulae are members of the bipolar class. Although only about 10 percent of all planetaries display an obvious two-lobed shape, researchers believe that most planetaries are double-sided to some degree, and that they display a bipolar form strongly during some stage of their evolution.

Beautifully symmetrical bipolar planetaries are among the most spectacular objects imaged by the Hubble Space Telescope and other large instruments. In 1987 planetary-nebula specialist Bruce Balick coined the term "butterfly nebulae" to cover their incredible diversity of shapes and color. Researcher Sun Kwok's latest book, Cosmic Butterflies, presents numerous images of the sky's most visually appealing and dynamically interesting bipolar planetaries. Many are fairly large and have high surface brightnesses, making them especially appealing for amateur astronomers. With the use of a nebula filter and high magnification, a diligent observer may even be able to discern structure often hidden by conventional photography.