How the Sun Rises and Sets: Why It Rises in the East and Sets in the West
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The Sun rises in the east and sets in the west because the Earth is spinning on its axis from west to east — the Sun itself stays essentially still at the center of the Solar System while our planet turns beneath it. Almost everyone has watched the majestic scene of the Sun rising and setting. In a city it is hard to see this event in its full beauty, because the horizon is blocked by buildings and other large structures, so urban residents only see the Sun once it is already high above the horizon.
How does the Sun rise and set?
The Sun rises and sets as a result of Earth's daily rotation, which makes the Sun appear to travel across the sky from one horizon to the other. The full cycle — dawn, the diurnal arc of the Sun, and dusk — repeats roughly every 24 hours and divides each day into a lit half and a dark half. The two sections below describe what an observer actually sees at each end of that arc.
Sunrise
Sunrise is best observed in the countryside, and even better in an open field or out at sea. In the morning the dawn gradually kindles in the eastern part of the horizon, the sky takes on a fiery crimson colour, and at the same time a steady brightening begins. Then the small upper edge of the Sun's disc slowly appears from behind the horizon.
That edge grows little by little until at last the whole radiant solar disc stands above the horizon in its full splendour. For a moment it looks as though an enormous fiery-crimson ball is resting on the very surface of the Earth. This impression fades only as the Sun gradually climbs higher.
The Sun then seems to move steadily across the sky. Travelling all the time from left to right (for a Northern Hemisphere observer), it first rises higher and higher, its colour turning to an increasingly pale yellow while its apparent size shrinks. In astronomical terms sunrise is the moment the Sun's upper edge first crosses the horizon, which differs slightly from the everyday sense of "when it gets light"; twilight and dawn precede that moment. Atmospheric refraction bends the light so that the Sun is visible while geometrically still just below the horizon, which is why the disc looks flattened and slightly enlarged near the ground.
Sunset
Having reached its highest point, the Sun, still moving in the same direction, begins to sink and finally disappears completely behind the horizon. Just before it does, exactly as in the morning, the Sun near the horizon turns fiery crimson and again seems to swell in size.
The evening glow ignites. The sky in the direction of the setting Sun is washed with deep crimson, giving the impression of the reflected light of some great fire raging far away. The colours are especially lovely over the sea: not only the water but every surrounding object and person takes on a special hue and a particular sheen. On rare occasions the very last sliver of the disc flashes green — the green flash, an optical effect caused by the atmosphere splitting sunlight into colours.
Why does the Sun look red at sunrise and sunset?
The Sun looks red at sunrise and sunset because its light passes through a much thicker layer of atmosphere when the Sun is low, and that thick layer scatters away the blue and green wavelengths while letting the red, orange and yellow ones through. The same physics turns the daytime sky blue and the rising or setting Sun crimson — it depends only on the angle at which the light enters the air.
Earth's air envelope — the atmosphere
The atmosphere is the envelope of air surrounding the Earth, reaching "upward" to roughly a thousand kilometres. The atmosphere is densest at the Earth's surface and grows progressively thinner with height. We therefore live at the bottom of a deep, boundless ocean of air.
Inside this air ocean colossal storms rage, accompanied by electrical discharges; currents of air masses move about; and precipitation falls as rain, snow and hail. After rain a beautiful rainbow sometimes appears, and small solid bodies occasionally burst into the atmosphere, so that against the night sky we see the phenomenon of a meteor.
How the atmosphere holds back and scatters the Sun's rays
The atmosphere scatters and absorbs sunlight unevenly, and the thicker the layer of air the light crosses, the more of certain rays it holds back. At sunrise and sunset we view the Sun and the Moon through far thicker slabs of air than when these bodies stand high above the horizon, so more of their light is intercepted before it reaches us.
The atmosphere most easily holds back the blue and green rays and least of all the red, orange and yellow ones. Because of this, the Sun, the Moon and the patches of sky near them look crimson, orange or yellow-red in the morning and evening, when both bodies sit low at the horizon. The scattering of short-wavelength light by tiny molecules is named Rayleigh scattering; scattering by larger particles such as dust and water droplets is Mie scattering, which adds the whitish haze near a low Sun.
Volcanic eruptions can deepen these colours dramatically by loading the upper atmosphere with fine particles. After the eruption of Krakatoa in 1883 and again after Mount Pinatubo in 1991, observers worldwide reported unusually vivid red and purple sunsets that lasted for months — a direct, documented illustration of how added particles intensify atmospheric scattering across the electromagnetic spectrum.
Why the daytime sky is blue
The daytime sky is blue because air molecules scatter the short-wavelength blue light of sunlight far more strongly than the longer red wavelengths, spreading blue light across the whole dome of the sky. Thanks to the air, the sky appears bluish to us by day. In ancient times people mistook this blue air-curtain for some solid, "crystal" firmament — a dome that supposedly covered the flat surface of the Earth like a lid (more on this: How people imagined the Earth). When the Sun or Moon rises from or sinks behind the horizon, the same scattering strips out the blue and leaves the reddish, crimson tones described above, which is why the colour of the sky changes through the course of a day.
The real cause of the change between day and night
The real cause of day and night is that the Earth does not stand still but constantly rotates on an axis, completing one full turn each day. Because of this rotation, the Earth turns first one side of its surface, then another, toward the Sun's rays.
Earth's rotation on its axis
Earth's rotation on its axis is the spinning of the planet around an imaginary line running through the North Pole and the South Pole, and it is this spin — not any motion of the Sun — that carries us into and out of sunlight. On the lit hemisphere all of nature is awake under the life-giving rays; there it is day. The opposite hemisphere, turned away, receives no sunlight, so there it is night and nature sinks into sleep. The boundary between the lit and dark areas sweeps continuously around the globe.
The Earth completes one turn in 24 hours
The Earth completes a full rotation on its axis in about 24 hours, and that interval is exactly what defines our day. As the planet spins, its hemispheres trade places relative to the Sun, so where it was night, a few hours later day arrives, and the reverse. The rotational speed is not the same everywhere: at the Equator the surface moves at roughly 1,670 kilometres per hour, while toward the poles that speed drops to nearly zero, because points near the axis trace much smaller circles in the same 24 hours.
Along a single meridian the local time is everywhere the same, while different meridians keep different times. This fact imposes a definite order on almost every area of working life. When night falls, work stops nearly everywhere and people sink into sleep — yet at that very moment the working day is beginning on the opposite hemisphere. Transport, however, runs around the clock regardless of sunrise and sunset: rails guide trains, buoys guide river steamers, and lighthouses, the compass, radio, modern navigators and the starry sky help sea and air vessels find their way.
The Earth rotates from west to east
The Earth rotates from west to east, which is precisely why the Sun appears to come up in the east and go down in the west. Because the ground beneath us turns eastward, every celestial object — the Sun, the Moon and the stars — seems to drift in the opposite sense, westward, across the sky. This eastward spin is the single directional fact that explains the consistent left-to-right path of the Sun seen from northern latitudes.
Why it seems that the Sun moves and not the Earth
It seems that the Sun moves rather than the Earth because human senses cannot detect smooth, constant motion — only changes in speed or direction. A passenger in a steadily gliding train or ship feels stationary while the scenery slides past, and in the same way we, riding a smoothly spinning planet, perceive the sky as moving instead. Motion only ever has meaning relative to a reference frame; there is no such thing as absolute motion we could feel directly. The Sun's apparent journey across the sky is therefore an illusion produced by our own rotating reference frame, and the Sun itself holds an essentially fixed position at the heart of the Solar System.
The tilt of Earth's axis and its effect on the Sun's position
The Sun does not always rise due east because the Earth's axis is tilted about 23.5° relative to its orbit, so the point on the horizon where the Sun appears shifts north and south through the year. This single tilt explains the seasons, the changing length of day and night, and why the bearings of sunrise and sunset wander instead of staying fixed.
Earth's motion around the Sun
The Earth travels around the Sun once a year while keeping its axis tilted at the same angle and pointing in the same direction in space. Because the tilt stays constant as the planet orbits, the Northern Hemisphere leans toward the Sun for part of the year and away from it for the rest, producing the cycle of seasons. The Summer Solstice marks the day the Northern Hemisphere is tilted most toward the Sun, giving the longest daylight and the highest midday Sun; the Winter Solstice is the opposite, with the shortest day and the lowest Sun.
How the rising and setting points shift over the year
The points on the horizon where the Sun rises and sets move steadily north and south over the course of a year, tracing a different arc each day. The Sun's daily track is high and long around the Summer Solstice — bringing many daylight hours — and low and short around the Winter Solstice. Its altitude and azimuth at any given clock time therefore change with the season, which is why a fixed window catches direct sunlight at different angles in June and December. The annual figure-eight pattern the Sun traces if photographed at the same time each day is called the analemma, and the slight offset between clock time and true solar noon that creates it is the equation of time.
The Sun on the equinox days
On the equinox the Sun rises almost exactly due east and sets almost exactly due west everywhere on Earth, and day and night are very nearly equal in length. There are two such days each year — the Spring Equinox and the Fall Equinox — and they are the reference points from which the Sun's rising bearing swings northward toward the Summer Solstice and southward toward the Winter Solstice. Sunrise calculations exploit a useful hemispheric symmetry: the way the rising point shifts in the north mirrors the shift in the south.
Sunrise and sunset beyond the Arctic Circle
Beyond the Arctic Circle the Sun can stay above the horizon for 24 hours straight or never rise at all, because the steep tilt of the axis means parts of the polar regions face fully toward or fully away from the Sun for extended periods. The same logic applies symmetrically around the South Pole.
The midnight Sun and the polar night
The midnight Sun is the period near the Summer Solstice when, north of the Arctic Circle, the Sun never sets and circles low around the whole horizon even at midnight; the polar night is its winter counterpart, when the Sun never rises for days, weeks or months depending on latitude. In Gjøvik, Norway and other high-latitude places these phenomena structure daily life, while at the very North Pole the year is divided into roughly one long day and one long night. Latitude is the master control here: the higher the latitude, the longer these continuous-light and continuous-dark spells last.
The spherical shape of the Earth and its consequences
The Earth is a sphere, and that shape is why sunrise and sunset times, the length of the day, and the elevation the Sun reaches at noon all vary with latitude. Because a globe curves away in every direction, observers at different places see the Sun cross their local horizon at different clock moments, and the Sun's noon height shrinks as you move from the Equator toward the poles. At the Equator — through cities such as Libreville, Gabon — days stay close to twelve hours long all year and the Sun climbs nearly overhead, while temperate locations like Lisbon, Liverpool's Albert Dock, the Jersey Shore near Spring Lake, New Jersey, San Francisco, Jabalpur, the Tropic of Cancer regions, and Hawai'i see day length and solar elevation swing more widely with the seasons. The designer and thinker Buckminster Fuller popularised viewing this whole system as "Spaceship Earth," a reminder that we ride a turning globe rather than stand on a flat plane.
Mistaken ideas about the Earth in ancient times
In antiquity people believed the Earth stood motionless at the centre of the Universe while the Sun and all the other heavenly bodies revolved around it — and that this is why night gives way to day and day to night. This geocentric model dominated thought for many centuries before observation overturned it.
The geocentric model: the Earth at the centre of the Universe
The geocentric model placed a stationary Earth at the centre of everything, with the Sun, Moon and stars carried around it on revolving spheres. It seemed to match everyday experience — the ground feels still and the sky appears to turn — which is exactly the sensory illusion described earlier, and it is why the model survived so long despite being wrong.
The ideas of Cosmas Indicopleustes and other ancient thinkers
The monk Cosmas Indicopleustes, who lived in the sixth century AD, imagined the Universe as a chest of gigantic proportions. In his book Christian Topography he wrote that
"... the inhabited Earth rises from south to north ever higher and higher, so that the southern lands lie far lower than the northern. For this reason," he says, "the paradise rivers Tigris and Euphrates, flowing from north to south, run faster than the sacred river Nile, which flows from south to north. In the far north," he writes, "stands a great mountain behind which the Sun hides." From this, Cosmas Indicopleustes claimed, "comes the alternation of day and night."
In the view of Cosmas Indicopleustes, angels dwelt above the firmament and gathered the clouds, sending rain and snow, drought and cold, wind and storm. Science long ago demolished these mistaken ideas about the Earth and about the Sun hiding behind a northern mountain.
The shift to the heliocentric system of the world
The heliocentric model, set out by Nicolaus Copernicus in the sixteenth century, replaced the centred Earth with a Sun-centred system in which the Earth and the other planets orbit the Sun and the Earth also spins daily on its axis. This single reordering explained the apparent motion of the Sun, the cycle of day and night, and the seasons far more simply than the old spheres, and it is the framework still used today. Copernicus showed, in effect, that the motion people attributed to the sky belonged in truth to the ground beneath their feet.
The astronomical knowledge of ancient civilisations
Ancient civilisations tracked the Sun and stars with remarkable precision long before written astronomy, building monuments aligned to the solstices and equinoxes and timing their calendars by the sky. Many cultures watched for the heliacal, or dawn, rising of particular stars — the first morning a star becomes visible just before sunrise after a season of invisibility — to mark the turning of the year, and they noted how star visibility shifts across the months as the Earth moves around the Sun.
Ancient observatories and watching the Sun
Ancient observatories were arrangements of standing stones, mounds or horizon markers built to register where the Sun rose and set on key dates. Gobekli Tepe, dated to around 9000 BC, is among the oldest known monumental sites and shows that prehistoric peoples were already organising space around celestial events. The Bighorn Medicine Wheel in Wyoming, a ring of stones with radiating spokes, has cairns aligned to the Summer Solstice sunrise and to the heliacal rising points of bright stars — a practical horizon calendar built by Indigenous peoples of North America. Such sites used fixed foreground markers against the distant horizon so that the slow seasonal drift of the rising point could be read directly off the landscape.
Finding direction by the Sun: navigation and travel
You can navigate by the Sun because it rises in the eastern half of the sky, sets in the western half, and stands due south (in the Northern Hemisphere) at local noon — so its position and the shadows it casts reveal direction without any instrument. Practical sun navigation underlies desert and wilderness travel, and it adapts to season and latitude:
- Shadow-tip method at midday: at local noon the Sun is at its highest and a vertical stick casts its shortest shadow, which points along the north–south line — toward true north in the Northern Hemisphere.
- Seasonal correction: because the rising and setting points move through the year, an experienced navigator uses interpolation, estimating the Sun's true bearing for the date rather than assuming it rises exactly due east.
- Tropical and equatorial considerations: near the Equator and within the tropics the midday Sun may stand to the north or to the south depending on the date, so the shadow rule must be applied with care.
Resources such as The Beginner's Guide to Natural Navigation collect these techniques, and travel writing by authors like Tom Melham for National Geographic documents how explorers across the Atlantic Ocean, Canada, Texas and beyond have read the Sun and stars to find their way.
Hands-on activity: building a model of the Sun's motion
You can understand Earth's rotation and the Sun's apparent path by building a simple sun-track diorama that records where the Sun sits in your sky through a day or across the seasons. This kind of visual demonstration turns abstract astronomy into something you can measure and see:
- Place a clear dome (half a plastic bottle or a salad bowl) over a sheet of paper and mark your observer position at the centre.
- Every hour, use a marker to dot the dome at the point where the Sun lines up with the centre, building up the Sun's diurnal arc.
- Repeat the chart near a solstice and near an equinox to compare the high summer track with the low winter one and the due-east-to-due-west equinox track.
- Stand a vertical stick beside the dome and trace its shadow to connect the model to real shadow navigation.
Citizen-science programmes such as Journey North and educational resources from NASA, the Stanford SOLAR Center, the StarChild and HEASARC projects — work associated with educators such as Dr. Laura A. Whitlock — offer ready-made versions of these activities. Many such materials, along with images credited to contributors like Fraser Mummery, are shared under the Creative Commons Attribution 4.0 International licence, so they can be reused freely in classrooms.
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