At Times, Latitudes Higher Than ________ Degrees Can Have 24 Hours or More of Continuous Darkness.

SkyTellers Seasons activities for young children
See also: Middle school Seasons activities and resources

About Our Seasons

What causes our seasons?
We have seasons because Earth's axis – the imaginary line that goes through the World and effectually which the Earth spins — is tilted. It's tilted most 23.5 degrees relative to our plane of orbit (the ecliptic) effectually the Sun. Equally we orbit our Sun, our axis always points to the same fixed location in space. Our northern axis points almost straight toward Polaris, the N Star.

This picture shows World from its side as it orbits our Dominicus. The centrality is tilted and points to the North Star no matter where Globe is in its orbit. Because of this, the distribution of the Sun'southward rays changes. In June, in the northern hemisphere summer, the Sunday's rays — and warmth — reach all the way to the north pole. In December, in the northern hemisphere wintertime, the due north pole is tilted away from the incoming sunshine.

The "fixed" tilt means that, during our orbit effectually our Lord's day each year, different parts of Earth receive sunlight for dissimilar lengths of fourth dimension. It also means that the bending at which sunlight strikes different parts of Earth'due south surface changes through the year. Sunlight striking the surface at an angle is "spread" across a wider area compared to sunlight hitting perpendicular to Earth'south surface. Areas that receive more scattered sunlight receive less energy from our Sun. All of these factors combine to give Earth its annual cycle of seasons!

For role of our orbit the northern half of Earth is tilted toward the Lord's day. This is summertime in the northern hemisphere; there are longer periods of daylight, the Sun is college in the sky, and the Sunday's rays strike the surface more directly, giving united states warmer temperatures. The n pole is in constant daylight!

When the northern one-half of World is tilted toward the Sun, the southern hemisphere is tilted away. People in the southern hemisphere feel the shorter twenty-four hour period lengths and colder temperatures of winter.

During winter in the northern hemisphere, our northern centrality continues to point to the North Star, merely, because we accept moved in our orbit effectually the Sun, our northern hemisphere now points away from our Dominicus. The due north pole is completely dark and other places in the northern hemisphere experience the shorter day lengths and colder temperatures of winter as the Lord's day traces a lower arc across the southern heaven and the Sun'south rays strike the surface at a lower angle. When it is wintertime in the northern half of Earth, the southern hemisphere, tilted toward our Sun, has summer.

During fall and spring, some locations on World feel similar, milder, conditions. Earth has moved to a position in its orbit where its centrality is more than or less perpendicular to the incoming rays of the Lord's day. The durations of daylight and darkness are more equally distributed beyond all latitudes of the globe.

What doesn't cause the seasons?
The seasons are not caused by how far Earth is from our Sunday. Earth's orbit effectually our Sun has a slightly elliptical path (very slight!), and the Sunday is not exactly in the heart of the ellipse. This means that, during the twelvemonth, Earth is sometimes farther from our Sunday, and sometimes closer — but the difference is small (not and so for some other planets!). World is closest to our Sunday in January (perihelion) and the farthest away in July (World is 147.5 1000000 kilometers from the Sun when information technology reaches aphelion). If distance were the most important gene, the entire Earth would have summertime in January when we are closest to our Sun and wintertime in July when we are farthest away!

What are solstices and equinoxes?
Solstices occur when Earth's axis is pointed directly toward our Sun. This happens twice a year during World's orbit. Near June 21 the due north pole is tilted 23.v degrees toward our Sun and the northern hemisphere experiences summer solstice, the longest day of the northern hemisphere year. On that same day, the southern hemisphere is tilted 23.v degrees away from our Sunday and the southern regions of Earth experience the shortest mean solar day of the yr — the winter solstice.

The 2nd solstice occurs on December 21 or 22 when the north pole is tilting 23.5 degrees away from our Dominicus and the due south pole is inclined toward information technology. This is the shortest twenty-four hours of the year in the northern hemisphere — the northern hemisphere winter solstice.

Twice each yr, during the equinoxes ("equal nights"), Earth's axis is not pointed toward our Sun, but is perpendicular to the incoming rays. During the equinoxes every location on our Earth (except the extreme poles) experiences 12 hours of daylight and 12 hours of darkness. The vernal or leap equinox occurs in the northern hemisphere on March 21 or 22 (the fall equinox of the southern hemisphere). September 22 or 23 marks the northern hemisphere autumnal or fall equinox.

As Earth orbits our Dominicus, the position of its axis relative to the Sun changes. This results in a change in the observed superlative of our Sun higher up the horizon. For any given location on Earth, our Sun is observed to trace a higher path above the horizon in the summer, and a lower path in the winter. During jump and fall, it traces an intermediate path. This means that our Lord's day takes a greater amount of time tocross the sky in the summer and a shorter amount of fourth dimension in the winter. This effect is greater as yous motility toward the poles; people living near the equator feel only pocket-sized changes in daylight during the year. The modify is more extreme toward the poles.

During the northern hemisphere summer solstice, Earth is tilted such that the Dominicus's rays strike perpendicular to the surface at the Tropic of Cancer (23.5 degrees north latitude, corresponding to the tilt of Globe's axis). At (solar) noon, our Sunday is directly overhead in this location (and at a decreasing height in a higher place the horizon n and south of the Tropic of Cancer). At locations n, our Sun will be at its highest position higher up the horizon and will take the greatest corporeality of fourth dimension to cross the heaven. All northern locations have more than 12 hours of daylight. All locations south experience less than 12 hours of daylight. Locations above the Chill Circle (due north of 66.5 degrees latitude; 90 degrees minus the tilt of Earth's axis) receive 24 hours of sunlight. Locations below the Antarctic Circle (66.five degrees south latitude) feel 24 hours of darkness.

During the northern hemisphere winter solstice, the Sun'southward incoming rays are perpendicular to the Tropic of Capricorn at 23.5 degrees s latitude. The Sun'due south path is the everyman to a higher place the horizon in locations north of the equator, and these regions experience the shortest day of the twelvemonth. Betwixt the winter and summer solstices, daylight increases equally Earth continues its orbit effectually our Sun.

During the equinoxes, sunlight strikes perpendicular to the surface at Earth's equator. All locations on Globe, regardless of latitude, experience 12 hours of daylight and 12 hours of darkness. The spring equinox marks the change from 24 hours of darkness to 24 hours of daylight at Earth's poles . In these extreme locations, our Sun moves above the horizon at the spring equinox and does not go below the horizon until the autumn equinox.

Practice other planets take seasons?
Yeah! Other planets in our solar system experience seasons for the same reason World does; their axis of rotation is tilted. However, some planets — like Mars and Pluto — have elliptical orbits that effect in more extreme variations in altitude from the Sun as they revolve around information technology. This, combined with the axial tilt, causes greater seasonal variation.

Uranus has an extreme tilt of 82 degrees. It takes Uranus almost 84 Earth years to consummate its virtually circular path effectually the Sunday. The tilt means that the pole of each hemisphere is exposed nigh directly to the Sunday's rays during the summer solstice, and the contrary hemisphere is in constant darkness. Given Uranus' long period of orbit, this translates into a 20-year winter or summer!

			Spring Equinox*	Summer Solstice*	Fall Equinox*	Wintertime Solstice
	Length of year (days)	Spin axis tilt (degrees)	Spring begins	Summertime begins	Autumn begins	Wintertime begins
Mercury	88	<one	north/a	northward/a	n/a	n/a
Venus	224.7	two.6 or ane.77	n/a	n/a	n/a	n/a
Earth	365.25	23.4	Mar 20, 2018	Jun 21, 2018	Sept 22, 2018	Dec 21, 2018
Mars	687	25.ii	Mar 23, 2019	Oct 8, 2019	Apr 8, 2020	Sep 2, 2020
Jupiter	4331	3.1	n/a	n/a	northward/a	n/a
Saturn	ten,747	26.7	2009	2017	2025	2032
Uranus	30,589	97.8	2050	2072	2007	2030
Neptune	59,800	28.3	2046	2087	2128	2005

*Summer solstice refers to the time the due north pole of a planet is tilted toward the Sun.
Based on data from 1990.

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Source: https://www.lpi.usra.edu/education/skytellers/seasons/#:~:text=All%20locations%20south%20experience%20less,experience%2024%20hours%20of%20darkness.

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