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  2. Sidereal time - Wikipedia

    en.wikipedia.org/wiki/Sidereal_time

    Animation showing the difference between a sidereal day and a solar day. Sidereal time ("sidereal" pronounced / saɪˈdɪəriəl, sə -/ sy-DEER-ee-əl, sə-) is a system of timekeeping used especially by astronomers. Using sidereal time and the celestial coordinate system, it is easy to locate the positions of celestial objects in the night sky.

  3. Hour angle - Wikipedia

    en.wikipedia.org/wiki/Hour_angle

    Hour angle. The hour angle is indicated by an orange arrow on the celestial equator plane. The arrow ends at the hour circle of an orange dot indicating the apparent place of an astronomical object on the celestial sphere. In astronomy and celestial navigation, the hour angle is the dihedral angle between the meridian plane (containing Earth's ...

  4. Winkler index - Wikipedia

    en.wikipedia.org/wiki/Winkler_index

    The Winkler Index, sometimes known as the Winkler Scale or WinklerRegions, is a technique for classifying the climate of wine growing regions based on heat summation or growing degree-days. In the system, geographical areas are divided into five climate regions based on temperature converted to growing degree-days, and is commonly known as ...

  5. Global surface temperature - Wikipedia

    en.wikipedia.org/wiki/Global_surface_temperature

    Global surface temperature (GST) is the average temperature of Earth's surface. More precisely, it is the weighted average of the temperatures over the ocean and land. The former is also called sea surface temperature and the latter is called surface air temperature. Temperature data comes mainly from weather stations and satellites.

  6. Ricci curvature - Wikipedia

    en.wikipedia.org/wiki/Ricci_curvature

    Ricci curvature. In differential geometry, the Ricci curvature tensor, named after Gregorio Ricci-Curbastro, is a geometric object which is determined by a choice of Riemannian or pseudo-Riemannian metric on a manifold. It can be considered, broadly, as a measure of the degree to which the geometry of a given metric tensor differs locally from ...

  7. Motor fuel taxes in Canada - Wikipedia

    en.wikipedia.org/wiki/Motor_fuel_taxes_in_Canada

    Canada, like most countries, has excise taxes and other taxes on gasoline, diesel, and other liquid and gas motor fuels (collectively called fuel taxes), and also taxes electricity at various administrative levels. Most provinces and territories in Canada also have taxes on these motor fuels, and some metropolitan areas such as Montreal ...

  8. Julian day - Wikipedia

    en.wikipedia.org/wiki/Julian_day

    As stated above, the Julian date (JD) of any instant is the Julian day number for the preceding noon in Universal Time plus the fraction of the day since that instant. Ordinarily calculating the fractional portion of the JD is straightforward; the number of seconds that have elapsed in the day divided by the number of seconds in a day, 86,400.

  9. Goods and services tax (Australia) - Wikipedia

    en.wikipedia.org/wiki/Goods_and_services_tax...

    Goods and Services Tax[ 1 ] (GST) in Australia is a value added tax of 10% on most goods and services sales, with some exemptions (such as for certain food, healthcare and housing items [ 2 ]) and concessions (including qualifying long term accommodation which is taxed at an effective rate of 5.5% [ 3 ]). GST is levied on most transactions in ...