Orbit Quiz

Every question comes from a page on The Orbital Record, and every answer links back to it. Those pages are written from primary sources: mission and observatory releases from NASA, ESA and ESO, and the peer-reviewed papers behind them. Numbers are given the way those pages give them, usually rounded, and the explanation after each answer says what the measurement was.

The weekly set is chosen in your browser from the calendar week (ISO weeks, which start on Monday), with a fixed random seed, so everyone sees the same ten questions and the set changes on Monday without anyone pressing a button. Up to three come from news stories published in the 60 days before that Monday, so the quiz follows what astronomers are finding now. The rest rotate through the question bank, so a question does not come back until most of the others have had their turn.

A quiz checks what you remember, not how science works it out. Some answers, like the age of the universe or the number of known planets, are the best current measurements and will be refined. When a question is about a single new result, the linked story says whether it is peer reviewed and what would confirm it.