# Equation of time: Quiz

Question 1: On ________ the difference between sundial time and clock time can be as much as 50 minutes, due to the considerably greater eccentricity of its orbit.
MarsWater on MarsDeimos (moon)Phobos (moon)

Question 2: Naturally, other ________ will have an equation of time too.
PlanetJupiterMercury (planet)Solar System

Question 3: the obliquity of the ________ (the plane of the Earth's annual orbital motion around the Sun), which is inclined by about 23.44 degrees relative to the plane of the Earth's equator; and
EclipticJupiterMoonSolstice

Question 4: Apparent (or true) solar time can be obtained for example by measurement of the current position (hour angle) of the Sun, or indicated (with limited accuracy) by a ________.
Tropical yearTime zoneSundialLongitude

Question 5: Another set of tables was published in 1672/73 by John Flamsteed, who later became the first royal astronomer of the new ________.
National Maritime MuseumRoyal Observatory, GreenwichImperial War MuseumBarbican Centre

Question 6: The former is caused by ________, and shifts the equinox backwards compared to the stars.
Axial precession (astronomy)PrecessionGeneral relativityForce

Question 7: This variation is due to the apparent ________ of the rotating Earth through the year, as seen from the Sun at solar midday.
PrecessionForceAxial precession (astronomy)General relativity

Question 8: The equation of time is the difference between ________ and mean solar time, both taken at a given place (or at another place with the same geographical longitude) at the same real instant of time.
Sidereal timeSolar timeSundialDay

Question 9: Next, knowing λ, calculate α using ________ for the right triangle on the celestial sphere shown above[15]
Spherical trigonometryAl-JayyaniSpherical geometryGreat-circle distance

Question 10: Note also that the date and time of periapsis (perihelion of the Earth orbit) varies from year to year; a table giving the connection can be found in ________.
Orbital eccentricityStandard gravitational parameterApsisOrbital period