Why is the sunset red? – Ytterbium Zone

Question: Why is the sunset red?
- Keywords:
  red,
  sunset
Asked by 782yttc52 to Anna, Hayley, Iain, Rebecca on 15 Jun 2015.
- Iain Bethune answered on 15 Jun 2015:
  
  Just before sunset, the light of the sun has to travel the longest distance through the atmosphere (the shortest is at midday when the sun is directly overhead). Of all the colours of light emitted by the sun, red has the longest wavelength and gets ‘scattered’ (or reflected away) the least. So it ends up looking reddish.
- anon answered on 15 Jun 2015:
  
  I can’t add anything to Iain’s perfect explanation – just some beautiful pictures I’ve found online: http://www.huffingtonpost.com/2013/04/29/beautiful-sunset-photos-around-the-world_n_3175797.html

Question: Why is the sunset red?