Abstract: A personal observatory structure including a base having an open top, and a hemispherical dome having a center point, the dome being shaped to be mounted on the base and to selectively enclose the open top. The hemispherical dome includes a first dome segment and a second dome segment pivotally connected to the first dome segment. The second dome segment has an outer radius smaller than the inner radius of the first dome segment. The first dome segment at second dome segment are connected together by pivotal connectors for movement about a pivot axis. One of the domes can be pivoted from a lowered position, in which the dome segments together enclose the open top of the base, to a raised position which exposes the interior and nests one dome segment within the other. The pivot axis may be a horizontal pivot axis that extends through the center point, and the dome segments may be shaped generally in the form of a quarter sphere.