Stars (except for the Sun) appear as tiny dots in the sky as their light travels through the many layers of the Earth's atmosphere, the light of the star is bent (refracted) many times and in random directions (light is bent when it hits a change in density - like a pocket of cold air or hot air). Stars twinkle when we see them from the Earth's surface because we are viewing them through thick layers of turbulent (moving) air in the Earth's atmosphere. The scientific name for the twinkling of stars is stellar scintillation (or astronomical scintillation). Proxima Centauri is 4.3 light-years from the Sun. The closest star to us is the sun! Other than that, the closest star is Proxima Centauri, aka Alpha Centauri C (the dimmest star in the Alpha Centauri system). The process of forming a new nucleus (and element) is nucleosynthesis.įor more information on nuclear fusion in stars, click here. This reaction is called nuclear fusion because it fused the nuclei (center) of atoms together, forming a new nucleus. In most stars, the primary reaction converts hydrogen atoms into helium atoms, releasing an enormous amount of energy. In the center of stars, atoms are taken apart by tremendous atomic collisions that alter the atomic structure and release an enormous amount of energy. For more in-depth information on galaxies, click here.Īll groups of stars are held together by gravitational forces. Our solar system is located in the Milky Way Galaxy, a spiral galaxy. Huge, organized collections of stars are called galaxies. Examples of open clusters include the Pleiades and Hyades. An open cluster is a loose collection of up to about 1,000 stars. These are relatively unorganized collections of stars. There are larger groups of stars, called clusters. These remote objects lie mostly around the central bulge of spiral galaxies. About half of all stars are in a binary star system.Ī globular star cluster is a spherical group of up to a million stars held together by gravity. Two stars that are locked in elliptical orbit around their center of mass (their barycenter) are called a binary star system. In the universe, most stars occur in groups of at least two stars. The composition of stars is studied using spectroscopy in which their visible light (the spectrum) is studied. The largest stars have the shortest life span (still billions of years) more massive stars burn hotter and faster than their smaller counterparts (like the Sun). As the nuclear fuel runs out (in about 5 billion years), the star expands and the core contracts, becoming a giant star which eventually explodes and turns into a dim, cool object (a black dwarf, neutron star, or black hole, depending on its initial mass). A star is born when an enormous cloud of hydrogen gas collapses until it is hot enough to burn nuclear fuel (producing tremendous amounts heat and radiation). Our subscribers' grade-level estimate for this page:Įach star in the sky is an enormous glowing ball of gas. Today's featured page: Short Opinion Worksheets - Printable The Stars - Zoom Astronomy Advertisement.Į is a user-supported site.Īs a bonus, site members have access to a banner-ad-free version of the site, with print-friendly pages.