can you mention a few units that come under the si system?
Second, metre, kilogram, ampere, kelvin, mole, and candela.
International System of Units
It comprises a coherent system of units of measurement starting with seven base units, which are the second (the unit of time with the symbol s), metre (length, m), kilogram (mass, kg), ampere (electric current, A), kelvin (thermodynamic temperature, K), mole (amount of substance, mol), and candela (luminous intensity, cd).
characteristics of stars based on the characteristics of the sun A star with mass greater than 0.4 times the Sun's will expand to become a red giant when the hydrogen fuel in its core is exhausted. have these been observed since ancient times? UNANSWERABLE how are they measured? It is often most convenient to express mass, luminosity, and radii in solar units could you please explain the second term? It is an absolute measure of radiated electromagnetic power, the radiant power emitted by a light-emitting object. howe is it measured? In SI units, luminosity is measured in joules per second, or watts and in astronomy, in the terms of the luminosity of the Sun, L how is it measured for a star? By its size in terms of solar radii, R, and effective temperature in kelvins what is this last unit that you mentioned? It is the base unit of temperature in the International System of Units (SI) why was it redefined? So that Boltzmann constant takes the exact value by whom was this unit formulated? William Thomson, later ennobled as Lord Kelvin you mentioned about an international system earlier, what is it? It is the modern form of the metric system; only system of measurement with an official status in nearly every country in the world. when was it introduced? 1960 which organization controls it? General Conference on Weights and Measures (CGPM)
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International System of Units [SEP] Introduction
The International System of Units (SI, abbreviated from the French "") is the modern form of the metric system. It is the only system of measurement with an official status in nearly every country in the world. It comprises a coherent system of units of measurement starting with seven base units, which are the second (the unit of time with the symbol s), metre (length, m), kilogram (mass, kg), ampere (electric current, A), kelvin (thermodynamic temperature, K), mole (amount of substance, mol), and candela (luminous intensity, cd). The system allows for an unlimited number of additional units, called derived units, which can always be represented as products of powers of the base units.