Celestial Tour: Coronagraph

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French astronomer Bernard Lyot invented the coronograph, a tool designed to create an eclipse on demand.

Produced by the Space Telescope Science Institute, Office of Public Outreach, in collaboration with NASA’s Universe of Learning partners: IPAC, Jet Propulsion Laboratory, Smithsonian Astrophysical Observatory, and Sonoma State University.
Images and Animations:
  • 2017 total solar eclipse from Whiskey Mountain, Wyoming: Miloslav Druckmüller, Jana Hoderová, Peter Štarha, and Shadia Habbal
  • Bernard Lyot at Pic du Midi: l'Observatoire de Paris
  • Sun eclipsed by Lyot’s coronagraph: The Science Museum (UK)
  • Solar prominence viewed using Lyot’s coronagraph: l'Observatoire de Paris
  • Sunlight blocked by a coronagraph: STScI
  • Comet NEAT imaged by the Solar and Heliospheric Observatory (SOHO): NASA, ESA, SOHO
  • HD 61005 star system imaged by the Hubble Space Telescope: NASA, D. Hines (Space Science Institute, New Mexico Office in Corrales, New Mexico), and G. Schneider (University of Arizona)
  • HD 139664 star system imaged by the Hubble Space Telescope: NASA, ESA, and P. Kalas (University of California, Berkeley)
  • AU Microscopii star system imaged by the Hubble Space Telescope: NASA, ESA, J. R. Graham and P. Kalas (University of California, Berkeley), and B. Matthews (Hertzberg Institute of Astrophysics)
  • Coronagraph revealing an exoplanet: Walt Feimer, Scott Wiessinger, Neil Gehrels, NASA's Goddard Space Flight Center Conceptual Image Lab  
  • Exoplanet orbiting HR 8799: Jason Wang (UC Berkeley) and Christian Marois (NRC Herzberg)
  • Exoplanets, artists’ conceptions: NASA, STScI
  • Written by Margaret W. Carruthers
  • Designed by Dani Player
  • Science review lead: Dr. Brandon Lawton
  • Education lead: Timothy Rhue II
  • Additional editorial input from: Dr. Lynn Cominsky, Sonoma State University; Dr. Sabrina Stierwalr, IPAC/Caltech; Dr. Tiffany Meshkat, IPAC/Caltech
  • Music courtesy of Associated Production Music

A black sphere in the center of a grey white background. Text, coronagraph. Eclipse on demand.
Overhead view of moon orbiting earth.
Text, During a total solar eclipse, the moon blocks the blinding light of the sun. Illustration not to scale.
Stars, planets, and features of the sun's corona that are otherwise invisible during the day appear in the darkened sky.
Image of moon in front of sun. Whiskey Mountain, Wyoming, August 21, 2017. Labels, the moon, star, solar corona.
Text, In 1930, French astronomer Bernand Lyot invented the coronagraph, a tool designed to mimic this rare natural event, creating an eclipse on demand. Solar prominence viewed using coronagraph. Sun eclipse by Lyot's coronagraph.
A basic coronagraph consists of a disk that blocks more than 99.99% of the sunlight passing through the telescope.
Though complex in detail, a coronagraph works essentially the same way your hand does when blocking the glare of high beam headlights.
Labelled diagram. Sunlight, lens, coronagraph, image of the corona.
Today, coronagraphs allow us to map streamers, monitor solar eruptions, and track comets as they round the sun.
Video of comet neat, solar and heliospheric observatory.
Coronagraphs can also be used to eclipse the light of objects outside the solar system, allowing us to see faint details in the space around them.
Image, HD g-1-0-0-5 star system, Hubble space telescope.
We can use coronagraphs to study disks of dust, rock, and ice surrounding individual stars within the Milky Way.
Image, HD 1-3-9-6-6-4 star system.
Debris disks like this, shining in the reflected light of their stars, contain the building blocks of planets. AU micro scopii star system.
Animation of zooming out from a planet in space. Text, Artist Conception.
By blocking the light emitted by a star, we can also detect the much dimmer light of a planet.
A black sphere over the star light.
Text, This animation of four exoplanets orbiting their star was made using data collected over the course of seven years.
Exoplanets orbiting star HR 8-7-9-9, Keck Observatory.
Direct imaging, collecting light directly from an object to create actual photographs, helps us determine important characteristics of exoplanets, such as mass, orbit, and atmospheric composition.
Combined with more powerful telescopes and advances in computer data processing, future coronagraphs will give us the opportunity to study exoplanets in even greater detail. and better understand the variety of worlds that exist in the universe. Five planets in the sky.