You would want this observation to be in an area with a lot of biotic and abiotic factors, so the best place for it is an ecosystem.
Answer: Senescent cells
The Senescence of
the eyes is often demonstrated by the presence of <span>senescence cells. They are forms of cells that are normally capable of
replication within mammalian tissues but permanently non-dividing and
share features with oncogene-induced senescence.
</span>Moreover, the accumulation of senescent cells has been overwhelmingly
studied using fibroblasts and has been proposed to act as an ageing mechanism.
The planet would be Neptune and Earth's average time is 365.2 days aka a full year (1 year).
I know carbon dioxide is, I don’t think oxygen and water vapour are. I don’t know the others, sorry
