A:Early Greek astronomers named the galaxy "Via Lactea" in reference to the pale band of light formed by stars along the galactic plane. The origin of the name, which translates as "Road of Milk," has been lost to time.
A:The Earth's tilt on its axis is what causes the change in the seasons and explains why summer days are longer than winter days. The Earth orbits in an ellipse around the Sun, and because of this, it draws closer to the Sun at some points than at others. It is the direction of the Earth's tilt in its axis that determines the length of days and nights.
A:Terrestrial navigation is a field of study that helps sea-faring people locate points at sea and on the land. Similarly, it involves being able to identify the position of the ship anywhere in the world. Students are instructed in the use of nautical charts, compass corrections and voyage planning.
A:Scientists will never know the farthest star from Earth, as the star is so far away that its light has not, nor will ever, have enough time to reach Earth. Even the stars within the visible universe are far too numerous to count, but the farthest one that humans have ever detected is about 55 million light years away. This incredibly distant star is called SDSS J 122952.66 +112227.8.
A:The sun and planets follow the ecliptic, an imaginary plane in the celestial sphere tilted approximately 23.5 degrees relative to the celestial equator. Earthbound observers see the sun and planets move along the ecliptic arc, rising up from the east and setting in the west.
A:Vestigial structures support the theory of evolution by adding observable evidence to the model of common ancestry. Vestigial structures are not necessarily without function. In fact, according to Austin Cline at About.com, it isn't possible to demonstrate that any anatomical feature serves no purpose. Instead, a vestigial structure is one that shows clear homology with a similar feature in related organisms but whose purpose is no longer clear.
A:Tissue and organ systems are different hierarchical levels of biological organization. Dr. Ingrid Lobo explains for Nature Education that biological organisms are systems of complexity. The basic functional unit of life is a single cell, and cells similar in function assemble to form tissue. An organ is a collection of different tissues joined as a functional unit; a group of organs working together to perform a specific task is an organ system.
A:The structure of RNA is a single-stranded molecule made up of basic units called nucleotides that contain a nitrogenous base, a five-carbon sugar and a phosphate group. Although there is only one strand of RNA, as opposed to the two stranded double helix of DNA, it does not always follow a linear pattern. Sometimes the molecules form loops and the nitrogenous bases bond.
A:The two main parts of the nervous system are the central nervous system and the peripheral nervous system. The central nervous system consists of the spinal cord and the brain, which contains 100 billion nerve cells. The peripheral nervous system is broken down into the somatic and autonomic nervous systems.
A:Texas A&M University indicates that the organelle that breaks down sugar to produce energy is the mitochondria. This process, which involves turning sugar into energy, is called cellular respiration.
A:Photosynthesis is the process that drives nearly all of the energy economies on Earth. It is the mechanism by which plants and green algae do the work of converting sunlight into an effective fuel for driving protein and carbohydrate synthesis. These biomolecules are then used by the plant for its own growth and reproduction.
A:Plutonium naturally forms in the heart of a star undergoing supernova, along with virtually all of the heavy elements in the universe. It is not found on Earth due to its instability. The most stable isotope of naturally occurring plutonium has a half-life of only 82,000,000 years and is exhausted well before it can be taken up in planetary formation. However, humans have been able to artificially create plutonium.
A:Match heads contain phosphorus, potassium chlorate and sulfur, and when heated by friction, the phosphorus ignites, causing the other two materials to burn. When ignited, the potassium chlorate produces oxygen in amounts far exceeding what is typically found in the surrounding air. The oxygen and sulfur mixture burns steadily, igniting the matchstick to produce a usable flame.
A:Stored kerosene can go bad. When kerosene is being stored, condensation can seep into the container and cause a problem. Sludge can develop from the mold and bacteria within the kerosene, and that causes it to break down.
A:Natural light is produced by natural processes, such as the sun and stars. By contrast, man-made devices, such as flashlights and light bulbs, emit artificial light. All forms of light require the release of energy, and in the natural world, this includes explosions, fires and similar phenomenon.
A:The word "porous" refers to a material that has pores, or holes in its surface; some examples of porous materials include sponges, pumice stones and cork. Some porous materials have more noticeable pores than others, and this quality of porousness is described as a material's porosity. Human skin is porous, for example, and pores are more pronounced on some people's skin than on others.
A:Crude oil mainly consists of hydrocarbon molecules, but impurities, such as sulfur, nitrogen, oxygen, iron, arsenic, vanadium, copper, nickel, sodium chloride, calcium chloride and magnesium chloride, are also present. The hydrocarbon molecules include straight chains, branched chains and rings.
A:Green and orange make brown. Per Color Matters, green and orange are both secondary colors, meaning that they are made by mixing two primary colors. Mixing any two secondary colors yields a brown shade, from muddy brown to olive brown.
A:Hot pink can be made from two parts red, one part blue and one part violet, with white added to achieve the desired brightness. Hot pink is a combination of primary colors and secondary colors, which are colors mixed from the primary colors of red, blue and yellow.