r/spacequestions↗
spacequestions: for all your questions about space
SpaceQuestions is a subreddit for asking questions about astronomy, rocketry, astrophysics and cosmology. We welcome everyone to post questions to satisfy their curiosity and further their scientific understanding. Our most common questioners fit into two categories: the scientifically curious, and fiction authors wanting to add realism into their stories. Please be courteous in your replies and help everyone to learn more about space together.
12k subscribers67 posts / mo in Sep 202661 authors / mosince 2013
r/spacequestions has 12k members (+42% over the last 12 months). It gets about 67 posts a month from 61 people. Top topics: Solar System Scale & Planets, Moon and Earth Dynamics and Mars Colonization & Terraforming.
When to post on r/spacequestions
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How r/spacequestions has grown
Subscriber growth
Subscribers over time
Monthly activity
Posts, comments and authors per month
Topics and brands on r/spacequestions
Top topics
Share of the subreddit's posts
- Solar System Scale & Planets1.5%
- Moon and Earth Dynamics0.8%
- Mars Colonization & Terraforming0.7%
- Habitable Exoplanets0.6%
- Water Worlds & Exoplanet Atmospheres0.6%
Brands people mention
Most-mentioned brands and sites, last 12 months
- NASA
- xkcd
- arXiv.org e-Print archive
- European Space Agency
- Omni Calculator
Everything else about r/spacequestions
Posting rules and account requirements, how often posts get removed, who writes here (age, gender, countries), what people ask for, how they talk, and related subreddits — all in the full report.
Posts and activity for Sep 2026. Members from Reddit's subscriber counts. Read from the same data the app runs on. Our research