The concept of Hubble expansion is a cornerstone of modern cosmology starting from the early days of its development in the 1920's and 30's. However, one of the crucial issues - what is the spatial scale at which the Hubble expansion begins to operate - remains unclear till now. Moreover, this question became especially important in the last 25 years in the context of dark-energy-dominated cosmology: Since the dark energy is distributed perfectly uniformly everywhere, one can expect the cosmological effects even at very small (e.g., interplanetary) scales. To address the above-mentioned issues, a series of biannual conferences "Cosmology on Small Scales" was organized in 2016. These meetings gather not only specialists in theoretical and observational cosmology, but also mathematicians, geophysicists, planetologists, etc. to discuss the problem from various points of view. The upcoming 5th conference CSS 2024 will continue this tradition and is aimed at a presentation of the most recent theoretical ideas and observational findings.