the dense atmospheric layers
81Watercolor painting — For other uses, see Watercolors (disambiguation). An artist working on a watercolor using a round brush Watercolor (US) or watercolour (UK and Commonwealth), also aquarelle from French, is a painting method. A watercolor is the …
82marine ecosystem — Introduction complex of living organisms in the ocean environment. Marine waters cover two thirds of the surface of the Earth. In some places the ocean is deeper than Mount Everest is high; for example, the Mariana Trench and the… …
83Marine habitats — Coral reefs provide marine habitats for tube sponges, which in turn become marine habitats for fishes Littoral zone …
84Mars — This article is about the planet. For other uses, see Mars (disambiguation) …
85eye disease — Introduction any of the diseases or disorders that affect the human eye (eye, human). This article briefly describes the more common diseases of the eye and its associated structures, the methods used in examination and diagnosis, and the… …
86Mount Vesuvius — This article is about the mountain/volcano in Italy. For other uses, see Vesuvius (disambiguation). Mount Vesuvius Monte Vesuvio …
87Meteoroid — A few shooting stars can be seen in this video from the ISS. A Perseid meteor (light streak somewhat to right of center of photo) and Milky Way. A meteoroid is a sand to …
88Orbital spaceflight — Discovery rockets to orbital velocity, seen here just after booster separation An orbital spaceflight (or orbital flight) is a spaceflight in which a spacecraft is placed on a trajectory where it could remain in space for at least one orbit. To… …
89Deep sea communities — giant tubeworm Deep sea communities currently remain largely unexplored, due the technological and logististical challenges and expense involved in visiting these remote biomes. Because of the unique challenges (particularly the high barometric… …
90technology, history of — Introduction the development over time of systematic techniques for making and doing things. The term technology, a combination of the Greek technē, “art, craft,” with logos, “word, speech,” meant in Greece a discourse on the arts, both… …
