Astrobiology Glossary W – Space

Term Definition
Wave A vibration in some media that transfers energy from one place to another. Sound waves are vibrations passing in air. Light waves are vibrations in electromagnetic fields.
Wavelength The distance between two wave crests. Radio waves can have lengths of several feet; the wavelengths of X-rays are roughly the size of atoms.
Weak Force The force that governs the change of one kind of elementary particle into another. This force is associated with radioactive processes that involve neutrons.
White Dwarf Star The hot, compact remains of a low-mass star like our Sun that has exhausted its sources of fuel for thermonuclear fusion. White dwarf stars are generally about the size of the Earth.
Wide Field / Planetary Camera (WF/PC) A collection of eight separate, yet interconnected, cameras originally used as the main optical instrument on the Hubble Space Telescope. Four cameras were used in tandem to observe in either wide-field, low-resolution mode or narrow-field, high-resolution (‘planetary’) mode. The Wide Field and Planetary Camera 2 replaced the WF/PC during the December 1993 servicing mission.
Wide Field and Planetary Camera 2 (WFPC2) The Hubble Space Telescope’s ‘workhorse’ instrument, WFPC2 snaps high-resolution images of faraway objects. Its 48 filters allow scientists to study precise wavelengths of light and to sense a range of wavelengths from ultraviolet to near-infrared light. The instrument has four CCDs (charge-coupled devices), which collect information from stars and galaxies to make photographs. WFPC2 was installed aboard the Hubble telescope during the December 1993 servicing mission.