For ten points, name this Danish composer of the twentieth century.
This composer's flute concerto features a duet between the solo flute and the bass trombone, supposedly because the flautist and the bass trombonist of the orchestra premièring the work hated each other. One overture by this composer depicts the sun travelling across the sky; that work is the Helios Overture. This composer is best known for his six symphonies; the four movements of his second symphony depict the four temperaments of man, while his fourth symphony is entitled The Inextinguishable. For ten points, name this Danish composer of the twentieth century.
This composer's flute concerto features a duet between the solo flute and the bass trombone, supposedly because the flautist and the bass trombonist of the orchestra premièring the work hated each other.
Carl {Nielsen}