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Cosmic rays or astroparticles are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar System in our own galaxy, [1] and from distant galaxies. [2]
Water covers about 71% of Earth's surface. [1] The origin of water on Earth is the subject of a body of research in the fields of planetary science, astronomy, and astrobiology. Earth is unique among the rocky planets in the Solar System in having oceans of liquid water on its surface. [2] Liquid water, which is necessary for all known forms of ...
The study of light, known as optics, is an important research area in modern physics. The main source of natural light on Earth is the Sun. Historically, another important source of light for humans has been fire, from ancient campfires to modern kerosene lamps.
Hydrosphere. The hydrosphere (from Ancient Greek ὕδωρ (húdōr) 'water' and σφαῖρα (sphaîra) 'sphere') [ 1][ 2] is the combined mass of water found on, under, and above the surface of a planet, minor planet, or natural satellite. Although Earth 's hydrosphere has been around for about 4 billion years, [ 3][ 4] it continues to ...
However, this type of radiation is significantly absorbed by the Earth's atmosphere, which is a radiation shield equivalent to about 10 meters of water. [7] The alpha particle was named by Ernest Rutherford after the first letter in the Greek alphabet, α, when he ranked the known radioactive emissions in descending order of ionising effect in ...
Evolution of photosynthesis. The evolution of photosynthesis refers to the origin and subsequent evolution of photosynthesis, the process by which light energy is used to assemble sugars from carbon dioxide and a hydrogen and electron source such as water. It is believed that the pigments used for photosynthesis initially were used for ...
The existence of nearly all life on Earth is fueled by light from the Sun. Most autotrophs, such as plants, use the energy of sunlight, combined with carbon dioxide and water, to produce simple sugars—a process known as photosynthesis. These sugars are then used as building-blocks and in other synthetic pathways that allow the organism to grow.
In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or a material medium. [ 1][ 2] This includes: electromagnetic radiation consists of photons, such as radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, and gamma radiation (γ) particle radiation consists of ...