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How is the solar system defined?

While the existence of other planets was known for centuries, the idea of a solar system was not considered until the 17th century. Prior to this, Earth was considered the center of the universe. Nicolaus Copernicus, Galileo Galilei, Johannes Kepler and Isaac Newton all contributed to developing the definition of the solar system.\nAt the center of the system is the sun, a ball of gas so massive that its gravitational pull governs the orbits of bodies 3.6 billion miles away. The bodies closest to the sun are the planets Mercury, Venus, Earth and Mars. The other planets in the solar system are ..

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What are some anatomical features of the ankle?

There are a series of ligaments that hold together the ankle bones, such as the plantar ligament, the posterior talofibular and tibiofibular ligaments, and the anterior talofibular and tibiofibular ligaments. The deltoid and syndesmotic ligaments also help to keep the ankle stable. Besides providing stability, the ligaments of the ankle allow the foot to move up and down like a hinge.\nThe muscles that make up the ankle include the long extensor hallucis longus muscle, which stretches from the tibia down to the big toe, and the much shorter extensor hallucis brevis muscle. There are also the p..

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What is an area in which an oceanic plate descends into the mantle called?

The Earth's crust consists of a number of tectonic plates that slide over the mantle. Subduction zones are associated with many geologic phenomena, such as volcanoes, earthquakes and tsunamis. The Pacific Ring of Fire is an example of the subduction of oceanic plates. Many of the world's largest volcanoes and most powerful earthquakes are found in the waters surrounding Japan, Russia and Canada.

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What is considered low barometric pressure?

Barometric pressure drops with altitude, so pressure at one altitude may appear higher at a lower altitude. In reading a barometer, however, the trend in readings is more important than the reading itself. If barometer readings are consistently falling that may mean a storm is coming. Sunny conditions may be indicated by barometer readings that are steadily rising. An exception to this occurs during exceptionally low readings, which may indicate the approach of a severe storm, regardless of the overall trend.

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How long does it take to travel around the earth at light speed?

The speed of light has been theorized by early philosophers and scientists, such as Aristotle and Galileo. In 1975, it was known that the speed of light was 299,792,458 meters per second. At the speed of light, an object can travel from the Earth to the moon in 1.3 seconds, from the Earth to the sun in 8.3 minutes and from the sun to the nearest star in 4.2 years.

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What is the definition of a mitotic spindle?

According to Biology Online, the mitotic spindle develops outside the nucleus during mitosis. Nature Education reports that the mitotic spindle plays a role in chromosome division during metaphase and anaphase. During the beginning of mitosis, centrioles create poles at the opposite ends of the cell. During metaphase, chromosomes line up in the center of the cell, and the cell undergoes a checkpoint to ensure chromosomes are attached to the spindle prior to cell division. During anaphase, the spindle separates chromosomes to the opposite poles of the cell.

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How is sulfur used?

Sulfur is a naturally occurring element that is often associated with volcanic activity, states the RSC. However, it contaminates fossil fuels, causing acid rain when the fuels are burnt unpurified, which is why sulfur is almost entirely acquired through purification processes that remove sulfur from natural gas, oil and coal. This element is used in bleaching paper and preserving foods. Sulfate derivatives are used in numerous surfactants and detergents, and around 100 million tons of calcium sulfate are mined every year for use in cement and plaster.\nThe RSC explains that sulfur is importan..

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What are some methods biologists use to determine evolutionary relationships?

One method of classifying organisms dates to the dawn of classical taxonomy and involves a gross anatomical comparison between the physical traits of living things. The similarities between them can thus be plotted into a rough tree of likely kinship between species. According to Rediscovering Biology, this method works well with the classical system that was first developed by Charles Linn in the 18th century.\nA more modern method, and one that takes into account the true evolutionary relationships between living things, is known as cladism. This method aims at developing a true tree of life..

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What is 100 grams converted to pounds?

Both grams and pounds are used to signify the weight or mass of an object. One pound is equal to 0.035274 grams or 16 ounces. One ounce is equivalent to 28.3495 grams and one gram is the same as 0.001 milligrams. In the United States, pound is the universal unit used in measuring the weight of an object, though the gram is used often to denote the weight of non-liquid ingredients and food items. The word gram is derived from the Latin word "gramma," which means small object.

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What is a cell boundary called?

The cell membrane provides structure and form to the cell. It encloses the vital cell organelles and the dense jelly-like substance called the protoplasm. It protects the cell from the harsh environment outside the cell. The cell membrane is porous, allowing the exchange of gases, nutrients and excretory products. It is made up of proteins and phospholipids. These proteins and lipids are layered to give the membrane a bi-layered structure.

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