Definition

1. Noun:
   • A unit of luminous intensity: "Standard candle" is the former name for the basic unit of luminous intensity in the International System of Units (SI). It is now officially called the "candela."
   • An astronomical object of known luminosity: In astronomy, a "standard candle" refers to a class of astronomical objects, such as certain types of stars or supernovae, whose intrinsic brightness is known. By comparing this known brightness to how dim the object appears from Earth, astronomers can calculate its distance.

Usage Examples

• Noun (Unit of Measurement):
  • The intensity of the light source was measured at ten standard candles.
  • The modern candela replaced the older definition of the standard candle.
• Noun (Astronomy):
  • Cepheid variable stars are a crucial type of standard candle for measuring galactic distances.
  • By identifying a supernova as a Type Ia standard candle, scientists could determine how far away its host galaxy is.

Advanced Usage

• "To use as a standard candle": In astronomy, this phrase describes the methodological use of an object with known luminosity for distance measurement.
  • Astronomers used the supernova as a standard candle to map the local universe.

Variants and Related Words

• Candela (n): The modern SI base unit of luminous intensity, which succeeded the standard candle.
  • One candela is approximately the luminous intensity of a common candle.
• Luminosity (n): The intrinsic brightness of a celestial object.
  • Knowing a star's luminosity is essential for it to serve as a standard candle.

Synonyms

• Candela (for the unit of measurement).
• Distance indicator or cosmic yardstick (for the astronomical object).

Related Idioms

• A candle in the dark: This idiom, while not directly using "standard candle," shares the metaphorical concept of a known reference point or source of guidance in uncertainty, similar to how an astronomical standard candle provides a reference for measuring vast, dark distances.
  • Her clear testimony was a candle in the dark for the investigation.

Noun

1. the basic unit of luminous intensity adopted under the Systeme International d'Unites; equal to 1/60 of the luminous intensity per square centimeter of a black body radiating at the temperature of 2,046 degrees Kelvin