- A star begins as a nebula, a cloud of gas and dust.
- Gravity causes the nebula to collapse, forming a protostar.
- As the protostar collapses, it heats up and eventually ignites nuclear fusion in its core, becoming a main-sequence star.
- The star spends most of its life in the main-sequence phase, fusing hydrogen into helium.
- When the hydrogen in the core is depleted, the star expands into a red giant (for low- or medium-mass stars) or a supergiant (for high-mass stars).
- Low- or medium-mass stars shed their outer layers, forming a planetary nebula, leaving behind a white dwarf.
- High-mass stars undergo a supernova explosion, leaving behind either a neutron star or a black hole.
- The remnants (white dwarf, neutron star, black hole) cool and fade over time.
Parent Tip: Review the logic above to help your child master the concept of life cycle of stars worksheet.
