Encyclopedia of Outer Space

Explore the universe, from stars and galaxies to space exploration. Read 434 articles, search for a topic, and save discoveries to revisit. START WITH FIVE FREE ARTICLES New readers can choose any five different articles. Your chosen articles stay unlocked, and revisiting them never uses another choice. Existing readers keep previously granted access. MAKE DISCOVERIES YOUR OWN • Search article titles and full text • Follow links between related topics • Save articles and return to your reading position • Continue recent reading and track your progress • Explore connections through the timeline and graph • Find article sources and image credits inside the app CHOOSE YOUR ACCESS Own the full encyclopedia with a one-time purchase for complete offline reading. Or choose monthly or annual Premium for the full encyclopedia plus AI chat grounded in this subject's articles. Eligible new Premium subscribers receive a three-day introductory trial. Subscriptions renew automatically unless canceled through your App Store account. Current local prices and terms appear before purchase. Restore Purchases recovers eligible previous purchases. Earlier full-version ownership includes encyclopedia and offline access; Premium AI requires a subscription. Internet access is required for AI chat and purchases. AI answers may contain errors; consult the linked sources. Article text is derived from Wikipedia. Images come from appropriately licensed Wikimedia Commons and other open sources. Source links, licenses and credits are available in the app. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/