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Dimming Starlight

Dimming Starlight

Dimming Starlight

  • Exhibition Text

    • Telescopes can easily zoom in on a star. But to see a dim object next to a star, such as a planet, astronomers need to block out the star’s light. A coronagraph attached to a telescope can eliminate nearly all the starlight, revealing dim objects nearby. With this coronagraph, researchers made the first discovery of a starlike object called a brown dwarf. Today coronagraphs are helping astronomers search for new planets.

      Hidden Planets

      If you looked at our Sun from a telescope 30 light years away, its light would be so bright it would obscure all the planets. Using a telescope with a coronograph, Jupiter and Saturn would become visible.

      The coronograph in this case was attached to the 60-inch (1.5 meter) wide telescope at the Palomar Observatory in southern California. With it, researchers made the first discovery of a brown dwarf as well as several "debris disks" where planets take shape.

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  • For Educators

    • Topic: Astronomy

      Subtopic: Stars

      Keywords: Astronomy, Brown dwarf stars, Coronagraphs, Light, Stars

      Audience: General

In This Section



Inside the coronograph, a series of mirrors and lenses position and focus the light. Carefully placed disks and rings block out 98.5% of the star's light, enabling astronomers to see dim objects near the star.

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