May 2, 2025 · Stars are giant balls of hot gas – mostly hydrogen, with some helium and small amounts of other elements. Every star has its own life cycle, ranging from a few million to trillions of years, and …

Dec 18, 2025 · Scientists call a star that is fusing hydrogen to helium in its core a main sequence star. Main sequence stars make up around 90% of the universe’s stellar population.

Dec 11, 2024 · Stars are the most basic building blocks of galaxies. The age, distribution, and composition of stars trace the history, dynamics, and evolution of their galaxy.

Dec 3, 2025 · By studying clusters of stars born from the same gas cloud at the same time, astronomers can test theories about stellar development, including how stars form, age, and evolve.

Sep 28, 2023 · Groups of stars make up galaxies, while planets and ultimately life arise around stars. Although stars have been the main topic of astronomy for thousands of years, we have begun to …

Dec 1, 2025 · Stars are spread all across the canvas of the sky, but they appear denser in places. For example, there are clusters of stars, like the Pleiades, and the region of the sky where the band of …

Aug 7, 2025 · The Orion Nebula is home to a star cluster defined by four massive stars known as the Trapezium. These stars are only a few hundred thousand years old, about 15-30 times the mass of …

Apr 14, 2025 · These massive cosmic neighborhoods, made up of stars, dust, and gas held together by gravity, come in a variety of sizes, from dwarf galaxies containing as few as 100 million stars to giant …

Oct 22, 2024 · Stars form inside vast, cold clouds of gas and dust, stellar factories called molecular clouds. They’re always in motion, and now and then part of a cloud begins to collapse in response to …

Aug 27, 2025 · Stars form in molecular clouds that are seeded with dust grains, elements, and molecules that may end up in the stars themselves — or near them, where planets may eventually form.