Methodology and sources
The steps behind a guide, from the first question to the last link.
Choosing topics
Each of the 45 guides answers one question people actually ask, such as what a dwarf planet is or how to tell if a rock is a meteorite. We avoid topics that depend on this week's news, so the guides stay useful over time. The topics are grouped into five categories: dwarf planets, asteroids, comets, meteors and impacts, and exploration.
Researching a guide
Writers open and read the pages they cite. They check dates, names and numbers against agency or research pages, usually more than one. A fact that could not be confirmed is left out or marked as uncertain. Each guide lists 4 to 7 sources at the end.
Where sources come from
We rely mostly on these publishers:
- NASA and its Jet Propulsion Laboratory, including the Center for Near Earth Object Studies.
- The European Space Agency and JAXA, Japan's space agency.
- The International Astronomical Union and the Minor Planet Center, which keep official names and orbits.
- The Smithsonian's National Air and Space Museum, the U.S. Geological Survey and The Planetary Society.
- University observatories and, for books, titles we are sure exist, with author, publisher and year.
Dates, numbers and units
Every guide shows a publication date and a "facts checked" date. Counts, rankings and mission status carry an "as of" date, because they change. Measurements are metric first, with U.S. units beside them. A conversion can differ slightly from the source because of rounding.
The quiz bank
The quiz wheel draws from 150 questions, 30 in each category. Every question has a single correct answer, a short explanation and a link to the page that supports it. A round never repeats a question. The quiz is for learning, so we avoid trick wording and facts that change often.
Illustrations
Diagrams and constellations are drawn for this site. They are schematic: orbits, sizes and distances are simplified and not to scale unless the caption says so. The constellations on the Star map are our own shapes and do not copy the official sky constellations.
Limits
These guides are an introduction. They do not replace textbooks, observatory data or teachers. Values change with new measurements, so for research or classroom work, check the linked source for the latest figure.