Exoplanets
TRAPPIST-1 b and e: similar sizes, different years
Compare two real planets with a scale diagram, a month of orbital motion, and calculations you can reproduce from NASA data.
Read guideCosmic Index / Field notes
Make sense of the measurements.
A number becomes useful when you know what it measures and what it leaves out. These guides pair the catalog tools with worked examples so you can reach a conclusion the data actually supports.
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Exoplanets
Compare exoplanets without mistaking size for habitability
Work through radius, mass, and orbital period comparisons, then check what the measurements leave unanswered.
Read guideSpace weather
Follow a space-weather event from the Sun to Earth
Connect solar events, upstream measurements, and geomagnetic activity without confusing an observation with a forecast.
Read guideSmall bodies
Read an asteroid flyby without turning it into an impact warning
Put lunar distances, size estimates, and hazard labels in context with a worked encounter comparison.
Read guideAbout these guides
Cosmic Index publishes these explanations alongside data from public scientific archives. Source links support the scientific definitions. Worked examples and instructions show how to use the tools; invented values are labelled and are never presented as current observations.
Catalog summaries are generated from published fields. A calculated comparison is not a new observation, and absent data remains unknown. For research, follow the source record and its uncertainties. For operational forecasts or impact assessments, use the responsible agency.
About Cosmic Index, data methods, and corrections
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