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The Pleiades cluster is home to thousands of young stars. The brightest form a tiny dipper that’s one of the best-known objects in the night sky.
But photographs reveal that there’s a lot more to the nebula than just its stars. They show wisps of blue around the entire cluster — the glow of a cloud of dust that spans dozens of light-years. It’s known as the Maia Nebula for one of the cluster’s brightest stars.
At first, astronomers thought the nebula was material left over from the birth of the Pleiades. But the cluster is at least a hundred million years old. That’s plenty of time for radiation from the cluster’s hottest stars to blow away any leftover dust and gas. What’s more, measurements show that the nebula is moving in a different direction from the stars. So it’s just a coincidence that they line up in the same direction.
The nebula is known as a reflection nebula because it’s reflecting light from the cluster’s brightest stars. That’s one of three main types of nebula.
A second is known as an emission nebula because it emits light. Ultraviolet energy from hot stars zaps hydrogen gas, splitting the atoms apart. When they link back up, the atoms produce red light.
A third type is a dark nebula. It’s a dense cloud of cold gas. It absorbs the light of the stars beyond it, so it looks like a dark hole in the starry background.
Look for the Pleiades climbing the eastern sky this evening, above Aldebaran, the bright orange eye of Taurus.
Script by Damond Benningfield