City data: GeoNames (geonames.org), under the CC BY 4.0 license. We use a selected list of 12,379 places from it.
Planet positions: Astronomy Engine by Don Cross, MIT license.
Type, served from this site: Newsreader (license), IBM Plex Mono as WB Mono (license), Silkscreen (license) and Galmuri9 by Lee Minseo, trimmed to the characters this site uses. Served from Google Fonts: Chiron GoRound TC and Gowun Batang. From Naver: NanumSquareRound. All under the SIL Open Font License 1.1.