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The post Earth Day Quiz: How Well Do You Know Our Earth? appeared first on Reader's Digest. Get green and test your knowledge of the environment, the oceans, animals, climate change, and more.
Earth is rounded into an ellipsoid with a circumference of about 40,000 km. It is the densest planet in the Solar System. Of the four rocky planets, it is the largest and most massive. Earth is about eight light-minutes away from the Sun and orbits it, taking a year (about 365.25 days) to complete one revolution.
The geological history of the Earth follows the major geological events in Earth's past based on the geological time scale, a system of chronological measurement based on the study of the planet's rock layers ( stratigraphy ). Earth formed about 4.54 billion years ago by accretion from the solar nebula, a disk-shaped mass of dust and gas left ...
The origin of life on Earth is not well understood, but it is known to have occurred at least 3.5 billion years ago, during the hadean or archean eons on a primordial Earth that had a substantially different environment than is found at present. These life forms possessed the basic traits of self-replication and inheritable traits.
Universal natural resources and physical phenomena that lack clear-cut boundaries, such as air, water, and climate, as well as energy, radiation, electric charge, and magnetism, not originating from civilized human actions. In contrast to the natural environment is the built environment.
Geologic time scale. The geologic time scale, proportionally represented as a log-spiral with some major events in Earth's history. A megaannus (Ma) represents one million (10 6) years. The geologic time scale or geological time scale ( GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating ...
Four temperaments. The four temperament theory is a proto-psychological theory which suggests that there are four fundamental personality types: sanguine, choleric, melancholic, and phlegmatic. [2] [3] Most formulations include the possibility of mixtures among the types where an individual's personality types overlap and they share two or more ...
Human physical appearance. Human physical appearance is the outward phenotype or look of human beings. Image of a Caucasian female (left) and an Asian male (right) human body seen from front (upper) and back (lower). Adult human bodies photographed whose naturally-occurring pubic, body, and facial hair have been deliberately removed to show ...