Baade’s Window

Our view of the center of the Milky Way isn’t good. The galaxy’s core lies behind heavy clouds of dust, which absorb most of the light from the stars behind them. But there are a few tiny “windows” in the dust. They provide pinhole views of the galaxy’s “bulge” — the congregation of mostly old stars in the Milky Way’s heart.

The best known of those pinholes is Baade’s Window. It’s close to Gamma Sagittarii, one of the brightest stars of Sagittarius.

The window was discovered in the 1940s by Walter Baade, who was looking for a way to locate the center of the galaxy. He found an especially bright patch in the summer Milky Way — the hazy band of light that outlines the galaxy’s disk. That patch is about twice as wide as the Moon, and it provides a view of the southern part of the bulge — less than 2,000 light-years from the center of the galaxy.

Baade used a class of pulsating stars to measure the distance to the bulge — about 27,000 light-years. Most of the stars in the bulge are quite old — about 10 billion years. And astronomers have even found planets orbiting a few of those stars — in the busy center of our home galaxy.

Sagittarius is low in the southeast as night falls. Its stars form the outline of a teapot. Gamma Sagittarii is at the top of the spout. Baade’s Window is just to the upper right of the star. Binoculars reveal a bright patch of stars, with a star cluster right in the middle.

Script by Damond Benningfield

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