sidereal

/sai'diəriəl/

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Word: Sidereal

Part of Speech: Adjective

Basic Definition: The word "sidereal" refers to things related to stars or constellations. When we talk about "sidereal time," we mean a way of keeping time based on the position of stars in the sky rather than the sun.

Usage Instructions:

• "Sidereal" is often used in scientific contexts, especially in astronomy and navigation.
• You can use it to describe time, systems, or bodies that are connected to stars.

Examples:

1. Basic Example: "Astronomers use sidereal time to make observations of the stars."
2. In a Sentence: "The sidereal year, which is about 365.256 days, is the time it takes for the Earth to orbit the Sun relative to the stars."

Advanced Usage:

• In advanced discussions about astronomy, you might hear terms like "sidereal day," which is the time it takes for the Earth to rotate once on its axis relative to distant stars, about 23 hours and 56 minutes.
• "Sidereal month" refers to the time it takes for the Moon to orbit the Earth relative to the stars, which is about 27.3 days.

Word Variants:

• Sidereally (adverb): This word means "in a way that relates to the stars." For example: "The planets move sidereally in the night sky."

Different Meanings:

• The primary meaning of "sidereal" is related to stars. However, it can also refer to systems or measurements based on the stars as opposed to the sun (like solar time).

Synonyms:

• Astral: Relating to stars.
• Celestial: Relating to the sky or space, especially the stars and planets.

Idioms and Phrasal Verbs:

• There are no common idioms or phrasal verbs that include the word "sidereal." It is mostly used in formal or scientific contexts.

Summary:

"Sidereal" is an adjective used to describe things related to stars and constellations, especially in astronomy. It helps scientists measure time and understand movements in the night sky.

Academic

Adjective

1. (of divisions of time) determined by daily motion of the stars
   • sidereal time
2. of or relating to the stars or constellations
   • sidereal bodies
   • the sidereal system