by definition, twilight is the the time of day when what celestial body is just below the earth's horizon?
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The middle place between light and nowhere, you dont wanna be the one left in there.
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SOLAR Eclipse Is When The MOON Is Directly Between The EARTH And SUN (Blocking The Suns Rays From The Earth)
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The moon rotates on its own axis and orbitrs the planet Earth as Earth orbits the sun.\n\n\nFrom Wikipedia and verified though other sources:\nThe Moon is Earth's only natural satellite. It has no formal name other than "The Moon", although in English it is occasionally called Luna (Latin for moon), or Selene, to distinguish it from the generic "moon" (natural satellites of other planets are also called moons). Its symbol is a crescent. The terms lunar, selene/seleno-, and cynthion (from the Lunar deities Selene and Cynthia) refer to the Moon (aposelene, selenocentric, pericynthion, etc.).\n\nThe average distance from the Moon to the Earth is 384,403 kilometers (238,857 miles). The Moon's diameter is 3,476 kilometers (2,160 miles).\nThe Moon makes a complete orbit about the Earth approximately once every 28 days. Each hour the Moon moves relative to the stars by an amount roughly equal to its angular diameter, or by about 0.5°. The Moon differs from most satellites of other planets in that its orbit is close to the plane of the ecliptic and not in the Earth's equatorial plane.\n\nSeveral ways to consider a complete orbit are detailed in the table below, but the two most familiar are: the sidereal month being the time it takes to make a complete orbit with respect to the stars, about 27.3 days; and the synodic month being the time it takes to reach the same phase, about 29.5 days. These differ because in the meantime the Earth and Moon have both orbited some distance around the Sun.\n\nThe gravitational attraction that the Moon exerts on Earth is the cause of tides in the sea. The tidal flow period, but not the phase, is synchronized to the Moon's orbit around Earth. The tidal bulges on Earth, caused by the Moon's gravity, are carried ahead of the apparent position of the Moon by the Earth's rotation, in part because of the friction of the water as it slides over the ocean bottom and into or out of bays and estuaries. As a result, some of the Earth's rotational momentum is gradually being transferred to the Moon's orbital momentum, resulting in the Moon slowly receding from Earth at the rate of approximately 38 mm per year. At the same time the Earth's rotation is gradually slowing, the Earth's day thus lengthens by about 15 µs every year. A more detailed discussion follows in the section titled Earth & Moon.\n\nThe Moon is in synchronous rotation, meaning that it keeps the same face turned to the Earth at all times. This synchronous rotation is only true on average because the Moon's orbit has definite eccentricity. When the Moon is at its perigee, its rotation is slower than its orbital motion, and this allows us to see up to an extra eight degrees of longitude of its East (right) side. Conversely, when the Moon reaches its apogee, its rotation is faster than its orbital motion and reveals another eight degrees of longitude of its West (left) side. This is called longitudinal libration.\n\nBecause the lunar orbit is also inclined to the Earth's equator, the Moon seems to oscillate up and down (as a person's head does when nodding) as it moves in celestial latitude (declination). This is called latitudinal libration and reveals the Moon's polar zones over about seven degrees of latitude. Finally, because the Moon is only at about 60 Earth radii distance, an observer at the equator who observes the Moon throughout the night moves by an Earth diameter sideways. This is diurnal libration and reveals about one degree's worth of lunar longitude.\n\nEarth and Moon orbit about their barycenter, or common center of mass, which lies about 4700 km from Earth's center (about 3/4 of the way to the surface). Since the barycenter is located below the Earth's surface, Earth's motion is more commonly described as a "wobble". When viewed from Earth's North pole, Earth and Moon rotate counter-clockwise about their axes; the Moon orbits Ea
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When you say sky you must mean atmosphere. It divides into:\n\ntroposphere: The troposphere is the lowest layer of the atmosphere starting at the surface going up to between 7 km at the poles and 17 km at the equator with some variation due to weather factors.\n\nstratosphere: from that 7–17 km range to about 50 km, temperature increasing with height. \n\nmesosphere: from about 50 km to the range of 80 km to 85 km, temperature decreasing with height. \n\nthermosphere: from 80–85 km to 640+ km\n\nexosphere: from 640 to 900 km - space.\n\nSo you can say the sky is am least 640 and at most 900 high.
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An equinox in astronomy is the moment when the Sun passes over the equator. The event occurs twice a year, around March 21 and September 23. The word equinox derives from the Latin word for equal night. The equinoxes are the two days each year when the middle of the Sun is an equal amount of time above and below the horizon for every location on Earth.\n\nIn the Northern Hemisphere, the March equinox is known as the vernal equinox and the September equinox is the autumnal equinox. In the Southern Hemisphere, the names are reversed.
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Also, we only see it when it is above the horizon.\n\nDuring the day, the sun is obviously above the horizon.  But the moon sets an hour or so later each day, so sometimes it is below the horizon in the day, and sometimes not.
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It's polar night in winter when the sun is sufficiently below the horizon, so that there is insufficient sunlight or no light at all. (A lingering dusk may occur, if the sun is only 12 degrees or less below the horizon.) \n\nA common misunderstanding is that at each point inside the polar circle the shortest day is totally dark. Because of twilight, this is not the case.\n\nSince the earth's axis is tilted with respect to the ecliptic by approximately 23 degrees 26 minutes (commonly rounded to 23 degrees and a half), the sun does not set at high latitudes in (local) summer. The duration of the midnight sun increases from one day during the summer solstice at the polar circle to approximately six months at the poles. At extreme latitudes, it is usually referred to as polar day. The length of the time when the sun is above the horizon varies from 20 hours at the Arctic Circle and Antarctic Circle to 186 days at the poles.
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I would expand this to say that a lunar eclipse occurs when the earth is positioned directly between the sun and the moon, and their plane of orbits align.\n\nThe last point is critical because you could easily wonder why we don't have lunar eclipses every month when the moon's orbit is such that the earth is in the middle... because the order of the planets is not only important, but that they line up just exact so that the earth's shadow does not fall just above or below the moon, but directly on it.
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It is called twilight.
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Solstice is either of the two points on the ecliptic at which its distance from the celestial equator is greatest and which is reached by the sun each year about June 22 and December 22.\n\nEquinox is either of the two points on the celestial sphere where the celestial equator intersects the ecliptic, or either of the two times each year (about March 21 and September 23) when the sun crosses the equator and day and night are everywhere of equal length.\n\nAll four days are recognized holidays in Pagan religions.
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The Planets Venus and Jupiter. Especially Venus as you will always find it close to the horizon in either the evening or morning. They are so bright that they seem to move with you like the illusion of the Moon following you, especially if you're driving. Also bright stars twinkle when they are low to the horizon due to atmospheric disturbances. \nOtherwise people might see airplanes, helicopters, weather balloons, satellites, or meteors.
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You could ask the same about the sun (although the angle of Earth's rotational axis makes things somewhat more complicated in the polar regions). The moon is simply so far from earth that your position on earth's surface becomes secondary. Half a day the earth's rotation will bring you onto the side where the moon is, half a day it will bring you onto the opposite side.\n\nI know from personal experience that the moon remains visible and fairly high on the horizon even beyond the arctic circle when the sun won't rise above the horizon any more. Apparently earth's rotational axis is (almost?) perpendicular to the plane in which earth and moon circle one another.
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u might have heard abt latitudes. Sun light constantly falls on earth. as earth moves different past of earth receives light and this is what we term as day and night. Latitudes help in determining times and it takes 15mins for sun to pass from one latitide to another. In other words we have time zones ever heard of green whtch time zone. This way, time is calculated with respect to sunrise and sunset. \n\nThus its all depending on how sunlight reaches in ur region..!
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at different times on the earth the sun is at different positions in the sky. When it's noon somewhere, it's midnight on the direct opposite side of the earth. If a particular time was called 12 noon to everyone it would seem silly to the people where it was midnight.
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The correct option is 'rotation of the earth'. When earth revolves, some part of it is directly facing the sun, and the other part is not. That explains the presence of day in one part of the world, and night in the other.
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We see the blue sky because of Rayleigh scattering.  Short wavelengths (blue light) are scattered more than long wavelengths (red light).\n\nAs the sun dips below the horizon, it doesn't get dark immediately.  We still see some light, this is twilight.  At night, even though sunlight is scattered, it doesn't scatter all the way around the globe.  Hence you eventually observe a black sky.
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Your shadow is longest just after the sun breaks over the horizon this event is called Dawn. Your shadow is shortest when the sun is directly overhead this even is called Noon. And yoru shadow is non-existent when there is no sun this event is called Night.