Starburst galaxies:
contain a large number of very young stars, but very little evidence of gas clouds.
contain a large number of very old stars and almost no gas or dust.
are often associated with a galaxy that is colliding with another galaxy.
are common in rich clusters.
are composed of filaments and voids.

are often associated with a galaxy that is colliding with another galaxy.

Explanation:

A starburst galaxy is a galaxy that undergoes very fast formation of stars. The rate at which stars are born is 100 times more than 3 solar masses per year of the Milky Way. The starburst is stage of the formation of a galaxy. After this stage is complete the stars will have used almost all the gas in it. As the star formation rate is very fast the difference between the age of the stars and the galaxy itself is very less. The star formation is triggered by mergers and tidal interactions between gas-rich galaxies.

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.