sidereal
Relating to stars
Sidereal relates to the stars or is measured by their apparent motion.
A sidereal day is the time it takes Earth to complete one rotation relative to distant stars—about four minutes shorter than a solar day.
Astronomers use sidereal time to track celestial objects: The telescope was calibrated to sidereal time.
Of the sky above
- equinoxSun crosses celestial midline
- eclipticSun's apparent annual path
- declinationAngular distance from equator
- parallaxPosition change from different vantages
astrometry · precession · observatory · telescope · magnitude · epoch · celestial sphere · meridian
Luminous astronomical object
- fixed starsStars appearing motionless
- constellationNamed pattern of celestial bodies
- binary starTwo stars orbiting together
- variable starCelestial body with fluctuating brightness
Location-finding via astronomical observation
- sextantMaritime angular measurement device
- astrolabeAncient altitude-measuring instrument
- star chartDiagram of celestial bodies
- PolarisCelestial north marker
wayfinding · mariner · latitude · longitude · bearing · compass · quadrant · nautical almanac
Precision timekeeping instrument
- solar daySun-based twenty-four hours
- rotationTurning on an axis
- atomic clockQuantum-vibration timekeeping device
- sundialShadow-based timekeeper
First zodiac sign
Virgo · Libra · Scorpio · Sagittarius · Capricorn · Aquarius · Pisces · constellations
Ancient Mesopotamian civilization
- SumeriansAncient southern Mesopotamian people
- EgyptiansNorth African Arab nation's people
- MayansPre-Columbian Mesoamerican civilization
- GreeksNatives of Athens' homeland
ziggurats · Ptolemy · ancient observatories · megalithic · calendar systems · cuneiform tablets
celestial
Of the sky above
- equinoxSun crosses celestial midline
- eclipticSun's apparent annual path
- declinationAngular distance from equator
parallax · astrometry · precession · observatory · telescope · magnitude · epoch · celestial sphere · meridian · zenith
star
Luminous astronomical object
- fixed starsStars appearing motionless
- constellationNamed pattern of celestial bodies
- binary starTwo stars orbiting together
celestial navigation
Location-finding via astronomical observation
- sextantMaritime angular measurement device
- astrolabeAncient altitude-measuring instrument
- star chartDiagram of celestial bodies
Polaris · wayfinding · mariner · latitude · longitude · bearing · compass · quadrant · nautical almanac · altitude
chronometer
Precision timekeeping instrument
- solar daySun-based twenty-four hours
- rotationTurning on an axis
- atomic clockQuantum-vibration timekeeping device
Aries
First zodiac sign
Leo · Virgo · Libra · Scorpio · Sagittarius · Capricorn · Aquarius · Pisces · constellations · birth chart
Babylonians
Ancient Mesopotamian civilization
- SumeriansAncient southern Mesopotamian people
- EgyptiansNorth African Arab nation's people
- MayansPre-Columbian Mesoamerican civilization
Greeks · ziggurats · Ptolemy · ancient observatories · megalithic · calendar systems · cuneiform tablets
siderealterrestrial
Relating to land
earthly · geosynchronous · mundane · local · geographic
- sidereal monthMoon's star-relative orbital period