Question

What is the Electromagnetic spectrum?

What’s the composition of sun ?

What are the Einstein special and general theories of relativity?

What is the Einstein mass-energy equivalence?

Spectral classes of stars ?

What is the main - sequence?

What’s the age of the universe?

What’s the proton-proton chain reaction ?

What are the four forces of nature?

What are the properties of the planets in the solar system?

Answer 1

1) The electromagnetic spectrum is a continuum (band) of all electromagnetic waves arranged according to frequency and wavelength. Almost all the bodies radiate at different wavelengths (especially celestial bodies) which can be determined using this spectrum.

2) The main element is Hydrogen (in the core by around 71 % of total mass) , Helium (27% of total mass), oxygen ( 0.97%) , carbon (0.4%), Nitrogen  the other 0.5% is made up of small amounts of many other elements such as neon, iron, silicon, magnesium  

3)  As per theory of special relativity, the laws of physics are the same for all non-accelerating observers, and the speed of light within a vacuum is the same for all observers no matter where they are.

As per general theory, there is no way for an observer to distinguish locally between gravity and acceleration.

4) E = mc²

5) Spectral classes are based on surface temperautre of bodies. Spectral classes are O, B, A, F, G, K, and M. The order is from hottest to coolest with O being the hottest and M being the coolest.

6) Main sequence stars are those that fuse hydrogen atoms to form helium atoms in their cores. About 90 percent of the stars in the universe, including the sun, are main sequence stars. Their size can be as massive as 200 times as sun

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