the.com/photometry
Measuring starlight like a bouncer counting how many photons made the guest list.
means The science of measuring the intensity and brightness of light, especially from stars and other sources.
from Built from Greek 'photo-' (light), from 'phos/photos', and '-metry', from 'metron' (measure) — the same measuring root that gives us geometry and symmetry. The term took shape as scientists in the 18th and 19th centuries worked out ways to quantify light's brightness rather than just describe it, turning 'how bright' from a matter of opinion into a matter of numbers.
- core trick
- Turns brightness into numbers, numbers into distance
- magnitude scale
- Backwards: lower number means brighter star
- planet hunting
- Spots exoplanets by catching tiny brightness dips
- ancient roots
- Hipparchus ranked stars by eye, 2000 years ago