Astro Glossary

Star Colors and Temperatures

Starbirth

The process in which a cloud of interstellar gas and dust collapses to form a new star. The collapse may be triggered by the shockwave from an exploding star, the gravity of a passing star cluster, or some other external source. The process fragments a cloud that may span many light-years into smaller pockets of matter, which collapse under their own gravitational pull. As such a pocket of matter collapses, its core gets hotter and hotter. When it gets hot enough, it triggers the process of nuclear fusion, which powers the newborn star.

StarDate radio

Stardust probe

Stardust flew through the coma of Comet Wild 2, gathering grains of comet dust that it returned to Earth in early 2006.

Stargazing and Skywatching

For more information about what to see in the nightsky tonight and this month, visit our Stargazing page.

Starquakes

Stars

A dense, glowing ball of hydrogen, helium, and trace quantities of heavier elements that shines with energy released from a hydrogen thermonuclear fusion reaction in the center, or core. Our Sun is an example of a star. Stars can appear red, orange, yellow, blue, or white, according to their masses and effective temperatures. Stars are born from clouds of gas and dust, live for millions or billions of years, depending on their masses, and die sometimes spectacular deaths. Stars usually exist in very large collections called galaxies.

Stereo probes

Solar TErrestrial RElations Observatory is the third mission in NASA’s Solar Terrestrial Probes program. This two-year mission will trace the flow of energy and matter from the Sun to Earth. It will reveal the 3D structure of coronal mass ejections; violent eruptions of matter from the sun that can disrupt satellites and power grids, and help us understand why they happen.

String Theory

A theory that proposes that subatomic particles are one-dimensional strings.

Subatomic Particles

Having a size smaller than the size of an atom, which is about one angstrom, or 10^-10 meters.