| 1. | | Tikoloshe (wikipedia.org) |
| 1 point by Schattenbaer on Jan 24, 2023 | past |
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| 2. | | NASA History: Apollo Waste Management System (nasa.gov) |
| 1 point by Schattenbaer on Dec 10, 2022 | past |
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| 3. | | Degradation of optical materials in solid-state lighting systems (researchgate.net) |
| 1 point by Schattenbaer on Dec 4, 2022 | past |
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| 4. | | Bortle Scale – a scale for night sky brightness and light polution (wikipedia.org) |
| 1 point by Schattenbaer on July 21, 2020 | past |
|
