Humans are not born with tails, except in the case of a birth defect, and cannot grow one by choice. However, humans do have tails during their development inside the womb. Plastic surgeons are also capable of installing tail-like implants.
A:Stars twinkle because they are point light sources. Passing through the atmosphere, the small beam of light constantly shifts by bouncing off particles in the air. Planets are closer, so they appear as discs, with the shifting of light from one side cancelling out the other.
A:Gravity is one of the fundamental forces of the universe, and it keeps us on Earth because it is relentlessly attractive. Every massive particle exhibits gravity by pulling closer to every other particle. The strength of this interaction is dependent on two quantities: the amount of mass and the distance between objects. It is possible to escape Earth's gravity if you have enough energy to speed up sufficiently.
A:A solar eclipse occurs when the Moon passes between the Sun and Earth so that the Moon's shadow falls on the Earth. A lunar eclipse occurs when the Earth passes between the Sun and Moon and the Sun casts the Earth's shadow on the Moon. Both events happen only when the Sun, Moon and Earth are aligned. A solar eclipse can only happen during a new moon, and a lunar eclipse can only take place on a full moon.
A:Astrolabes work by presenting users with a graphic interface that makes it relatively easy to compute the positions of the sun, the moon and the stars. Astrolabes can be used for navigation as well as predicting the exact times for sunrise and sunset. Turned on its side, an astrolabe can be used as a mechanical calculator akin to a slide rule.
A:Four layers of the earth's atmosphere containing various gases make up the composition of the sky. The layers of the atmosphere are divided into the troposphere, the stratosphere, the mesosphere and the thermosphere. The atmosphere's divisions occur according to temperature fluctuations.
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:Plants and animals are multi-cellular organisms composed of eukaryotic cells, while bacteria are single-cell prokaryotic organisms. Each eukaryotic cell of a plant or animal includes a central nucleus containing DNA and membrane-bound organelles, such as endoplasmic reticulum and mitochondria. A bacterial cell has no nucleus or membrane-bound organelles.
A:Silk comes from the cocoons of certain insects, such as the mulberry silkworm. When the insects create their cocoons, harvesters extract the fibers and spin them into thread. Each cocoon may contain more than 1,000 yards of fibers, but it takes several to create thread strong enough to make cloth.
A:One example of a parasitic relationship in coral reefs includes crustaceans from the Copepoda or Isopoda orders, which attach to fish in the reefs, sometimes causing harm but at other times simply holding on and feeding on food particles that float by them. Coral reefs feature organisms that coexist in a number of different relationships, including parasitism, but also symbiosis, competition, commensalism and mutualism.
A:Metabolic shock is a symptom of metabolic acidosis, which occurs when the body produces an excess of acid, or cannot rid itself of acid build-up. It can lead to rapid breathing, lethargy, confusion and in severe cases, death.
A:Natural selection leads to evolution because the traits of those who are able to reproduce influence future generations genetics and gradually lead to these passed on traits becoming the normal state of being, thus causing the species in question to evolve. If a group of people have predominantly brown hair genes and have children, then by way of natural selection the dominant gene will increase with future generations, meaning that slowly in time this group of people will evolve to have mostly brown hair genes.
A:Biotic environments consist of all living things in an ecosystem. All of the plants, animals, fungi and microbes in an environment are said to be its biotic component. The biotic component is distinguished from the abiotic, or nonliving, component, which is mainly comprised of the mineral, chemical and energetic components of the environment such as water, sunlight and soil.
A:Formaldehyde can also be known as methanal, which is the substance's systematic name, or by alternate names like methyl aldehyde, methylene glycol or methylene oxide. This chemical compound is the simplest member of the aldehyde functional group and has a chemical formula of CH2O or HCHO. Though it is a gas at room temperature, formaldehyde solutions are used in the preservation of biological specimens and as a disinfectant.
A:The term Calcium is based on the Latin words "calx" and "calcis," meaning "lime." The ancient Romans were known to make lime from limestone or calcium carbonate, a naturally occurring compound found in Earth's crust.
A:An alchemist is someone who practices alchemy. Alchemy is a form of science dating back to medieval times that concentrates on chemical science and speculative philosophy. It is also used to explain mysterious transformations.
A:Nitrogen is important to life because it comprises approximately 80 percent of the Earth's atmosphere and is present in all living things as a part of proteins and DNA, according to the Marine Biological Laboratory. Nitrogen is present in the amino acids that make up proteins. It is also essential to reproduction because it is present in the nucleic acids in genetic material, or DNA.
A:While exploring what happens when metals come in contact with acids, it is apparent that most, but not all, have some sort of reaction, usually forming hydrogen gas. The result is the production of salts.
A:Ebony is a very deep black derived from various tropical trees of the genus Diospyros. The wood comes from tropical and subtropical trees in southern India and Sri Lanka. The word "ebony" itself is commonly used as a synonym for the color black.
A:White is produced when all colors of the visible spectrum are combined. These colors are red, orange, yellow, green, blue, indigo and violet. They are the colors of the rainbow and can be easily remembered by the mnemonic ROY G BIV.
A:Refraction is the change in a wave's direction when it encounters a change in its transmission medium. The process of refraction allows eyes and lenses to form images. When the wave's medium changes, the velocity of the wave changes, but its frequency remains the same.
A:To make the color orange, you will need paints in red, yellow and white as well as a small dish and paintbrush for mixing. Mix the two primary colors and then add white to achieve the desired shade. The process should take only a few minutes, depending on how much of the color orange is being produced.
A:In the additive color process, red and green combine to make yellow. The three additive primaries are red, green and blue. In the subtractive color process, yellow is a primary color and cannot be created through mixing. The subtractive color primaries are cyan, magenta and yellow. The primary colors combine to form three secondary colors.