Astronomy terms starting with S

32 terms

  1. Scalar A constant number. 1, -16, .3534, 7346 are all scalars.
  2. Scatter When refering to photons and light, scattering describes the phenomenon of a source absorbing, and then emanating light in all directions.
  3. Sensitivity When referring to a medical test, sensitivity refers to the percentage of people who test positive for a specific disease among a group of people who have…
  4. Simultaneous Occurring at the same time.
  5. Solar Cycle An approximately 11-year pattern in the number of sunspots, coronal mass ejections (CMEs), solar flares, and other solar activity.
  6. Solar Eclipse The passing of the Moon between the Sun and Earth. In a total solar eclipse, the Moon blocks all light from the solar disk, allowing us to see the solar…
  7. Solar Flare An explosive release of electromagnetic radiation and huge quantities of charged particles from a small area of the solar surface.
  8. Solar Maximum The month(s) during the 11-year solar cycle when the number of Sunspots reaches a maximum.
  9. Solar Minimum The month(s) during the 11-year solar cycle when the number of Sunspots is lowest.
  10. Solar Spectral Irradiance (SSI) The amount of radiant energy of a particular wavelength that falls on a surface in a given amount of time.
  11. Solar System The Sun and the family of objects that orbit it. The Solar System includes things like planets, moons, comets and asteroids, and a mysterious form of…
  12. Solar Ultraviolet Irradiance The amount of energy released from the Sun in the ultraviolet portion of the spectrum at wavelengths shorter than 400 nm.
  13. Solar Wind A stream of plasma coming out of the Sun in all directions at very high speeds—an average of about 400 km/sec, or a million mph.
  14. Space Weather Refers to conditions on the Sun, in the solar wind, and in Earth’s space (magnetic field, ionosphere, and thermosphere) that can influence space- and…
  15. Spacetime The theory of relativity says that time cannot be treated absolutely separately from space, only in one observer's relative view.
  16. Spectra A range of different measurements. In terms of physics, spectra usually refers to the different wavelengths, or colors (if in the visible range) of light…
  17. Spectral Line An emission (bright) or absorption (dark) of light at a specific frequency or wavelength.
  18. Spectrograph A device that separates light by wavelength (color) in order to produce a spectrum that allows for the identification of elements within the light source.
  19. Spectrum Electromagnetic radiation arranged in order of wavelength from Ion wavelength radio waves to short wavelength gamma rays.
  20. Standard Candle A celestial object whose intrinsic brightness is known or can be estimated by some physical principle.
  21. Static Unchanging over a length of time.
  22. Steady State Theory A cosmological model where matter is created constantly as the universe expands so it remains homogenous and isotropic.
  23. Stochastic Random.
  24. Strong Force The interaction responsible for binding quarks, antiquarks, and gluons to make hadrons. Residual strong interactions provide the nuclear binding force.
  25. Structure Changes in the shape of the bottom of lakes, rivers, or impoundments, especially those that influence fish behavior.
  26. Sunspot Dark areas on the Sun created by strong magnetic fields beneath the Sun’s surface.
  27. Sunspot Cycle The recurring, eleven-year rise and fall in the number of Sunspots.
  28. Sunspot Group A cluster of multiple sunspots.
  29. Super Cluster A cluster of clusters of galaxies. A vast collection of galaxy clusters that may contain tens of thousands of galaxies spanning over a hundred million…
  30. Supernova Supernova refers to several types of stellar (meaning star) explosions that produce extremely bright objects that decline to invisibility over weeks or…
  31. Synthesis of Nuclei Combining protons and neutrons to form nuclei.
  32. Systematic Errors Measurement errors that are not random.