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Tolkien meant Arda to be "our own green and solid Earth", seen here in the Baltistan mountains, "at some quite remote epoch in the past". [1]In J. R. R. Tolkien's legendarium, the history of Arda, also called the history of Middle-earth, [a] began when the Ainur entered Arda, following the creation events in the Ainulindalë and long ages of labour throughout Eä, the fictional universe.
Illustration of different stars' internal structure based on mass. The Sun in the middle has an inner radiating zone and an outer convective zone. The radiative zone is the thickest layer of the Sun, at 0.45 solar radii. From the core out to about 0.7 solar radii, thermal radiation is the primary means of energy transfer. [74]
Sun path, sometimes also called day arc, refers to the daily (sunrise to sunset) and seasonal arc-like path that the Sun appears to follow across the sky as the Earth rotates and orbits the Sun. The Sun's path affects the length of daytime experienced and amount of daylight received along a certain latitude during a given season.
His hypotheses are that the fixed stars and the sun remain unmoved, that the earth revolves about the sun on the circumference of a circle, the sun lying in the middle of the orbit, and that the sphere of the fixed stars, situated about the same centre as the sun, is so great that the circle in which he supposes the earth to revolve bears such ...
In observations of the solar disk, cardinal directions are typically defined so that the Sun's northern and southern hemispheres point toward Earth's northern and southern celestial poles, respectively, and the Sun's eastern and western hemispheres point toward Earth's eastern and western horizons, respectively.
Aristarchus of Samos (/ ˌ æ r ə ˈ s t ɑːr k ə s /; Ancient Greek: Ἀρίσταρχος ὁ Σάμιος, Aristarkhos ho Samios; c. 310 – c. 230 BC) was an ancient Greek astronomer and mathematician who presented the first known heliocentric model that placed the Sun at the center of the universe, with the Earth revolving around the Sun once a year and rotating about its axis once a day.
It was on this day that George Reynolds tapped an oil reserve in modern-day Iran, the very first oil discovery in the Middle East. That. The energy industry and, in essence, the entire ...
Solar cycles are nearly periodic 11-year changes in the Sun's activity that are based on the number of sunspots present on the Sun's surface. The first solar cycle conventionally is said to have started in 1755. The source data are the revised International Sunspot Numbers (ISN v2.0), as available at SILSO. [1]