Denmark the 22 proposals have been agreed upon by a parliamentary majority. Denmark shares strong cultural and historic ties with its Scandinavian neighbours Sweden and Norway. It has historically been one of the most socially progressive cultures in the world. In 1969, Denmark was the first country to legalise pornography, and in 2012, Denmark replaced its "registered partnership" laws, which it had been the first country to introduce in 1989, with gender-neutral marriage. Modesty and social equality are important parts of Danish culture. The astronomical discoveries of Tycho Brahe (1546–1601), Ludwig A. Colding's (1815–88) neglected articulation of the principle of conservation
Stellar classification far right side of the diagram. Planetary nebulae are dynamic and tend to quickly fade in brightness as the progenitor star transitions to the white dwarf branch. If shown, a planetary nebula would be plotted to the right of the diagram's upper right quadrant. A black hole emits no visible light of its own, and therefore would not appear on the diagram. Several spectral types, all previously used for non-standard stars in the mid-20th century, have been replaced during revisions of the stellar classification system. They may still be found in old editions of star catalogs: R and N have