Luminous, gaseous planetary nebulae expand quickly and die young, when considered in astronomical years. When compact and symmetric, they can appear planet-like through a small telescope.
University of Hawaiʻi at Mānoa Institute for Astronomy Astronomer Roberto Méndez describes the evolution of understanding and unanswered questions about planetary nebulae in the latest issue of the IfA newsletter Nā Kilo Hōkū.
Scientists believe the ionized gas becomes visible as red giant stars transform into white dwarfs, he writes.
Read Méndez’ article, “Planetary Nebulae.”