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
Planetary surface to humans as it the primary habitat of the species, which has evolved to move over land and breathe air. Human space exploration and space colonization therefore focuses heavily on them. Humans have only directly explored the surface of Earth and the Moon. The vast distances and complexities of space makes direct exploration of even near-Earth objects dangerous and expensive. As such, all other exploration has been indirect via space probes. Indirect observations by flyby or orbit currently provide insufficient information to confirm the composition and properties of planetary surfaces. Much of what is known is from the use of