Measurement, Data & Statistics
How raw measurements become knowledge — deriving the properties of stars and galaxies, weighing black holes, mapping dark matter through rotation curves, and the calibration, error analysis, and honest uncertainty that make a measurement science.
Highlights
- ›Uncertainty is part of the method, not hidden
In brief
Deriving properties, and the statistics of measurement.
Techniques in this category
- Black-Hole Mass MeasurementTechniqueMeasures: The mass of a black hole
Weighing a black hole by the motion of what orbits it — stars near the galactic centre, gas in a disk, or the gravitational waves of a merger. The masses range from a few Suns to billions.
- CMB MeasurementsTechniqueMeasures: The early universe
Mapping the faint microwave afterglow of the Big Bang and its minute temperature and polarisation ripples. Their statistics — including the baryon acoustic oscillations frozen into them — pin down the composition, geometry, and age of the universe.
- Determining Stellar PropertiesTechniqueMeasures: The physical properties of stars
How the measurable — brightness, colour, spectrum, motion — becomes the physical: a star's temperature, luminosity, mass, radius, chemical composition (metallicity), and age, mostly inferred through models rather than measured directly.
- Error Analysis & CalibrationTechniqueMeasures: The reliability of a measurement
The discipline that makes a number science: calibrating instruments against known standards, tying measurements to common reference frames, propagating uncertainties, and stating the statistical confidence of a result. In astronomy, a measurement without an error bar is not a measurement.
- Galaxy Rotation CurvesTechniqueMeasures: Mass distribution in galaxies
Measuring how fast a galaxy rotates at each radius, usually from the Doppler shift of its gas. The stars orbit far faster than the visible matter can explain — the classic evidence that galaxies are embedded in halos of dark matter.
Knowledge connections
- Group includesCMB Measurements
- Group includesDetermining Stellar Properties
- Group includesGalaxy Rotation Curves
- Group includesBlack-Hole Mass Measurement
- Group includesError Analysis & Calibration
Sources
The primary and reference sources this topic draws on.
- NASANational Aeronautics and Space Administration
Mission data, planetary science, space telescopes, and public-domain imagery.
Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.