Although centuries ago astronomers thought that a supernova was a new star appearing for the first time in the heavens, today we know that it is:

a violently exploding star that releases light energy whose intensity can illuminate a whole galaxy.

Explanation:

A Supernova is a violent star explosion that causes the release of light that expands so many times and that is capable of illuminating a galaxy. It marks the end of a star and also results in the release of gamma rays, radio waves, x-rays, and heavy elements. Unlike a nova, a supernova destroys the star where it occurs.

A supernova is classified into Type I and Type II. Type I supernova produces three times more brightness than Type II and it occurs as a white dwarf absorbs hot gas from an associate star. The Type II supernova marks the end of the star. It lacks the ability to produce nuclear energy at its core and results in the collapse of the star.

firearm identification is the process of analyzing the bullets and cartridge cases left at a crime scene to determine if they came from a particular firearm. marks on the bullets and cartridges may be common to every firearm of that type. these are called class characteristics.

scattering of light by tiny particles in air to produce the colors we see on sky, is dependent on the following factors:

(i) wavelength of light

(ii) size of the scattering particle  

(iii) distance traveled by light through the atmosphere.

according to rayleigh's law of scattering, the amount of scattering is inversely proportional to the fourth power of its wavelength. shorter the wavelength, greater is its scattering. hence violet/blue light is scattered more than red.

sun's light is a composite light ( visible light) with wavelengths in the range 400 nm (violet) to 700 nm (red). as sunlight passes through our atmosphere, the molecules of air scatter light according to their wavelengths. during sunrise and sunset, the sun's position is below the horizon. hence light from the sun travels a greater distance in the atmosphere when compared to its position a noon.

as sunlight enters the earth's atmosphere, blue light is scattered away and at the end of its journey in the sky, only red and orange wavelengths remain in the beam.

hence at sunrise and sunset, the sky appears reddish orange.