May 2026
I ended my April Nature Notes by saying that we only have one planet Earth. As I write, four of us fellow humans are circumnavigating the Moon as it orbits Earth. Astronomers speak about colonising the Moon and other planets. I am extremely sceptical about this ambition. First, why? No known planet has a breathable atmosphere, or any other essential materials vital for supporting life. Secondly, how? Artemis 2 rocket was 100 metres tall before launch and had to use 990.88 tons of liquid hydrogen and oxygen fuel to escape Earth’s gravity. Just to carry 4 humans. So how would we transport all the materials, including sufficient oxygen/air, to build even a small (air-tight) building on the Moon? Let alone on another planet such as Mars which is 225 million kilometres from Earth. Thirdly, shouldn’t we just ensure that Earth is maintained in a sustainable way? Not only for humans, but also all other species that have no-where else to go. There are up to 11 million interdependent species on Earth, our ecosystem.
I do admit that I am fascinated by the work that NASA is doing, mainly because it is science, and I am a scientist. We should be striving to understand the natural universe that we inhabit. However, I do not believe this study will lead to a “planet B”. Earth is our survival module, and we must care for it for perpetuity. Ecology is derived from the Greek words Oikos Logos, meaning Home Study. We scientists are studying our home planet and trying to keep it sustainable. Sadly, the more we know, the more we realise that as our population grows, the harder it is to support all people, and all other organisms.
There is no life on the Moon or Mars or in the void of space. These are some of the key facts that I have been able to glean on Earth’s global biodiversity:
- Identified vs. Unidentified: Only about 1.2 to 2 million species have been formally described, named, and catalogued by scientists.
- Undiscovered Majority: Roughly 86% of terrestrial species and 91% of marine species are estimated to still await description.
- The Microbial Question: Some estimates suggest that prokaryotes (single-celled bacteria and archaea) could bring the species total up to 1 trillion (10¹²). Most species estimates exclude procaryotes.
- Distribution: Of the estimated 8.7 million multi-cellular organisms (eukaryotes), roughly 6.5 million live on land and 2.2 million in oceans.
- Highest Diversity: Insects (a subset of animals) constitute the largest group, with an estimated ~5 million+ species.
- Viruses are not included in any of these estimates.
Because of the high rate of species extinction due to habitat loss and climate change, many species may be vanishing before being discovered or catalogued. Please enjoy our Earthly Spring (living nature’s re-birth) and all it consists of.

