Chronyas is built on open data. This page lists where the information comes from and under which licence it is used. Wherever a licence asks for attribution, it is given here.
Events and dates
- Wikidata, the open knowledge base of the Wikimedia Foundation: titles, dates, places, categories and short descriptions of most events. Licence: CC0 (public domain dedication). wikidata.org
- Wikipedia is used only to count how many language editions cover a topic, which gives the importance ranking. No Wikipedia text is reproduced.
- DBpedia is used as a second source to cross-check the birth and death years of people; events whose years disagree are left out. No DBpedia text is reproduced.
Earth, climate and space
- NOAA National Centers for Environmental Information (NCEI): significant earthquakes, tsunamis and volcanic eruptions. US government data, public domain.
- US Geological Survey (USGS): earthquakes and geological data. US government data, public domain.
- NASA Goddard Institute for Space Studies (GISS): global temperature records. US government data, public domain.
- NOAA Global Monitoring Laboratory (GML): atmospheric carbon dioxide measurements. US government data, public domain.
- NASA Exoplanet Archive: the discovery of planets around other stars. US government data, public domain.
- Smithsonian Institution, Global Volcanism Program: eruptions of the world's volcanoes, cited to the programme and used under its terms of use. volcano.si.edu
- Our World in Data: long-run series on population, health and the economy. Licensed under CC BY 4.0. Attribution: data from Our World in Data (ourworldindata.org), licensed CC BY 4.0, with the underlying sources named there.
Maps and time scales
- Natural Earth: coastlines and country borders on the event maps. Public domain. naturalearthdata.com
- International Commission on Stratigraphy: the International Chronostratigraphic Chart, which gives the geological eras, periods and their boundary ages and colours. stratigraphy.org
Images
The background of each era, and the illustrations of events, are rendered by Chronyas itself from scripts. They are not photographs and do not show real scenes; they are reconstructions meant to give a feeling of each time.
Corrections
If you believe a date, a description or a licence statement is wrong, write to us on the contact page.