Observatory / Astronomical Association Ursa
KAIVOPUISTO, HELSINKI
(N/lat 60° 9.318’, E/lon 24° 57.518’)
Star, a medium-sized star is born as an interstellar cloud begins to condense. It is held together by gravity and, for the majority of its existence, radiates bright light and lives about ten billion years until the pressure inside it begins to reduce and material starts to cave in towards the star’s core. In the end of stellar evolution, the star gradually dies away. First it becomes a red giant, and then — when all the hydrogen in the core is fused to helium - the core collapses into a dense, hot, white dwarf. The outer layers expand slowly, becoming a planetary nebula.