ScienceDaily
Glossary · Telescopes & Instruments
Coronagraph
A mask inside the instrument that blocks a star so you can see what is next to it.
Invented in the 1930s to study the Sun's corona without waiting for an eclipse, the same idea now hunts planets. A physical occulter blocks the bright source and a series of stops suppress the light that diffracts around it. The engineering difficulty is extreme — suppressing a star by a factor of ten billion while preserving a planet a fraction of an arcsecond away — and it is the central technology of every future mission designed to image an Earth analogue.
Where it has come up lately
Related terms
Lagrange point
Five places where two bodies' gravity lets a third sit still relative to both.
Adaptive optics
Bending a mirror hundreds of times a second to cancel out the atmosphere.
Interferometry
Combining separate telescopes so they resolve detail like one enormous dish.
First light
The night a new telescope is pointed at the sky and actually works.
Questions
What is Coronagraph?
A mask inside the instrument that blocks a star so you can see what is next to it.
Why does it matter?
A physical occulter blocks the bright source and a series of stops suppress the light that diffracts around it. The engineering difficulty is extreme — suppressing a star by a factor of ten billion while preserving a planet a fraction of an arcsecond away — and it is the central technology of every future mission designed to image an Earth analogue.