Currently, the Indonesian government is constructing a national observatory on Mount Timau, Amfoang, Kupang. The selection of the Mount Timau area was based on the dry climate and sky conditions in the area which are still dark, far from light pollution, and it is easy to observe both the northern and southern skies. Behind the existence and construction of the national observatory, it turns out that the Amfoang people already have ethnoastronomical knowledge. Exploring this ethnoastronomical knowledge is the aim of this research, i.e., to minimize the potential conflict that could occur due to the impact of the construction of the Timau National Observatory of Indonesia (TNOI). The ethnoastronomical knowledge is still stored in people’s memories and is still conveyed orally. We hope that this ethnoastronomical knowledge can support Astro-tourism that is free of light pollution and also support the existence of the national observatory. Primary data consists of ethnoastronomical knowledge obtained using in-depth interview techniques and field observations. To support data analysis, this research uses collective memory, ethnographic and ethnoastronomical approaches. Through this research, it is proven that the Amfoang people already have ethnoastronomical knowledge which is useful for determining farming seasons, rainy seasons, dry seasons, disaster prediction, and time period for harvesting honey. The ethnoastronomical knowledge of the Amfoang people was then compared with a sky map to confirm the names and positions of the stars in the sky. Identification of stars or constellations is also used to find links between people’s beliefs and rational astronomical reasons.