Top Space & Astronomy subreddits

Largest Space & Astronomy subreddits

Largest Space & Astronomy subreddits

#	Subreddit	Members	12-mo growth	Commenters / mo
1	r/space	27.99M	+0.8%	8,634
2	r/nasa	5.88M	+1.4%	943
3	r/spaceporn	4.32M	+4.9%	7,060
4	r/spacex	3.7M	+0.9%	1,366
5	r/Astronomy	3.15M	+4.0%	3,529
6	r/ISRO	455,273	+2.1%	345
7	r/SpaceXLounge	385,349	+1.5%	1,288
8	r/spaceflight	315,621	+6.8%	686
9	r/telescopes	268,501	+20%	1,931
10	A r/askastronomy	185,430	+38%	4,105
11	r/astrophysics	172,633	+33%	812
12	r/Stargazing	155,392	+31%	862
13	r/jameswebbdiscoveries	149,705	+2.4%	22
14	r/cosmology	143,771	+20%	538
15	r/moon	139,881	+22%	764
16	r/jameswebb	130,746	+5.9%	72
17	r/SpaceXMasterrace	109,513	+14%	2,179
18	r/Mars	99,769	+29%	812
19	r/universe	79,763	–	868
20	r/meteorites	71,074	+38%	310
21	r/sun	67,954	+49%	194
22	r/ArtemisProgram	65,018	–	437
23	r/SpaceUnfiltered	55,368	+185%	254
24	r/BlueOrigin	52,963	+23%	785
25	r/AstronomyMemes	42,516	+50%	680

Fastest growing Space & Astronomy subreddits

Member growth over 12 months, among subreddits that had at least 18,251 members a year ago.

Fastest growing Space & Astronomy subreddits

#	Subreddit	12-mo growth	Members gained	Members	Commenters / mo
1	r/SpaceUnfiltered	+185%	+35,950	55,368	254
2	A r/amateurastronomy	+86%	+17,514	37,880	176
3	r/amateursatellites	+63%	+14,892	38,676	177
4	r/AstronomyMemes	+50%	+14,227	42,516	680
5	r/sun	+49%	+22,470	67,954	194
6	S r/SpaceVideos	+49%	+9,573	29,111	20
7	r/seestar	+46%	+11,767	37,482	832
8	A r/askastronomy	+38%	+51,541	185,430	4,105
9	r/meteorites	+38%	+19,634	71,074	310
10	r/solareclipse	+36%	+7,967	29,842	1,743
11	r/PerseveranceRover	+34%	+8,501	33,726	13
12	r/astrophysics	+33%	+42,927	172,633	812
13	r/Stargazing	+31%	+36,882	155,392	862
14	r/Mars	+29%	+22,723	99,769	812
15	r/ItsAlwaysPleiades	+27%	+8,582	39,860	54
16	r/BlueOrigin	+23%	+9,919	52,963	785
17	r/esa	+22%	+7,227	39,710	186
18	r/moon	+22%	+24,940	139,881	764
19	r/RocketLab	+21%	+7,146	41,684	263
20	r/cosmology	+20%	+24,426	143,771	538
21	r/telescopes	+20%	+45,235	268,501	1,931
22	r/Spaceexploration	+18%	+6,197	40,651	196
23	r/darksky	+18%	+6,170	40,821	189
24	r/SpaceXMasterrace	+14%	+13,674	109,513	2,179
25	r/SpaceLaunchSystem	+12%	+3,951	36,206	51

Most members gained

Space & Astronomy subreddits that gained the most members

#	Subreddit	Members gained	12-mo growth	Members	Commenters / mo
1	r/space	+229,752	+0.8%	27.99M	8,634
2	r/spaceporn	+200,405	+4.9%	4.32M	7,060
3	r/Astronomy	+121,024	+4.0%	3.15M	3,529
4	r/nasa	+83,971	+1.4%	5.88M	943
5	A r/askastronomy	+51,541	+38%	185,430	4,105
6	r/telescopes	+45,235	+20%	268,501	1,931
7	r/astrophysics	+42,927	+33%	172,633	812
8	r/Stargazing	+36,882	+31%	155,392	862
9	r/SpaceUnfiltered	+35,950	+185%	55,368	254
10	r/spacex	+33,279	+0.9%	3.7M	1,366
11	r/moon	+24,940	+22%	139,881	764
12	r/cosmology	+24,426	+20%	143,771	538
13	r/Mars	+22,723	+29%	99,769	812
14	r/sun	+22,470	+49%	67,954	194
15	r/spaceflight	+20,077	+6.8%	315,621	686
16	r/meteorites	+19,634	+38%	71,074	310
17	A r/amateurastronomy	+17,514	+86%	37,880	176
18	r/amateursatellites	+14,892	+63%	38,676	177
19	r/AstronomyMemes	+14,227	+50%	42,516	680
20	r/SpaceXMasterrace	+13,674	+14%	109,513	2,179
21	r/seestar	+11,767	+46%	37,482	832
22	r/BlueOrigin	+9,919	+23%	52,963	785
23	S r/SpaceVideos	+9,573	+49%	29,111	20
24	r/ISRO	+9,439	+2.1%	455,273	345
25	r/ItsAlwaysPleiades	+8,582	+27%	39,860	54

Most active Space & Astronomy subreddits

People who comment in a month, the average of the three months ending September 2026.

Most active Space & Astronomy subreddits

#	Subreddit	Commenters / mo	Posts / mo	Members
1	r/space	8,634	829	27.99M
2	r/spaceporn	7,060	503	4.32M
3	A r/askastronomy	4,105	446	185,430
4	r/Astronomy	3,529	928	3.15M
5	r/SpaceXMasterrace	2,179	351	109,513
6	r/TheRestIsScience	2,122	553	16,739
7	r/telescopes	1,931	847	268,501
8	r/solareclipse	1,743	664	29,842
9	r/spacex	1,366	181	3.7M
10	r/SpaceXLounge	1,288	207	385,349
11	r/SpaceInvestorsDaily	1,192	222	27,389
12	r/nasa	943	268	5.88M
13	r/universe	868	220	79,763
14	r/Stargazing	862	505	155,392
15	r/MarsSociety	850	410	18,692
16	S r/spacequestions	844	81	11,973
17	r/seestar	832	587	37,482
18	r/astrophysics	812	184	172,633
19	r/Mars	812	166	99,769
20	r/BlueOrigin	785	129	52,963
21	r/moon	764	647	139,881
22	r/spaceflight	686	158	315,621
23	r/AstronomyMemes	680	100	42,516
24	r/SpellcasterReviews	671	456	40,873
25	r/cosmology	538	72	143,771

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How these lists are made

• Members are the member counts measured in October 2026.
• Activity (commenters and posts per month) is the average of the three months ending September 2026. Posts by known bots are not counted.
• 12-month growth compares members now with members a year earlier. A subreddit is ranked by growth only if it already had at least 18,251 members a year ago (the median for subreddits with a known growth), so brand-new communities don't top the list from a base of zero. Subreddits with more monthly active users than 0.808 per member, a sign of inflated activity, are left out of the growth and activity lists.
• NSFW communities are excluded: those Reddit marks as 18+, those where most posts are NSFW, and the Adult Content topic.
• Topics follow Reddit's own community categories.
• The lists are rebuilt every month. Each list shows the top 25 (100 for the largest subreddits overall). Download all lists as CSV (free to reuse under CC BY 4.0, with a link to this page).