The ecliptic and the seasons - Solstice and Equinox - English version

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• published: 06 Nov 2012
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For comments and suggestions (errors in the translation of subtitles, for example), enter on this page. Thank you. Thanks to Herald Soares de Oliveira (Brazil) for his help in translating subtitles in Portuguese. Teaching in Astronomy: http://www.pawean.com/MVM/index.html The ecliptic is a fundamental level in astronomy. In this first part, described the plane and its relationship with Ecuador and the seasons of the year. The Earth has a number of periodic motions. Of these, the most important because of its intensity are two: the rotation on its axis and the rotation around the Sun These movements originate cycles in which we are all immersed: rotational movement is what gives rise to day and night and lasts 24 hours; translational motion is the cause of the seasonal cycle, and lasts 365 days, ie one year. The reason of the seasons lies in the special provision of the axis of rotation of the earth. The imaginary red line around the Earth is Ecuador. Ecuador is a fundamental background in astronomy is adopted for calculation of position, both on the surface of the earth as in heaven. The coordinates calculated based on this plane are called "equatorial coordinates." The line of the poles is perpendicular to this plane, and is the line around which Earth rotates. If we make visible the plane of Earth's orbit around the sun and project it into space until it intersects the globe, see that Ecuador does with Earth a 23 degree angle and a half. This is called "obliquity of the ecliptic" The ecliptic is the plane containing the Earth's orbit around the sun, and also, apparently line traveled by the sun over a year for stationary background of stars. This angle causes the earth in its annual cycle, orient their poles toward the sun. The image shows the tilt of the Earth during the winter. The clíptica plane is projected onto the southern hemisphere. The North Pole is farthest from the Sun than the South Pole. If we take the plane of the ecliptic, the position of the earth would be as shown in the image. It shows how the southern hemisphere receives sunlight more directly, Summer is the Southern while the Northern Hemisphere receives light at an angle: North is winter. Placing ourselves in the sun, this is reflected in the animation we see now: if we have the line of Ecuador on the plane of the ecliptic, it is summer in the Southern Hemisphere ... When the line goes, it is winter there and summer in the Northern Hemisphere. When two planes intersect in front of us, will be the beginning of the Fall or Spring: we are talking about the equinoxes. If we see the earth in schematic form, as in the pictures below, better observe what we mean. The ecliptic is represented here as a green circle. It is, in fact, the projection of the plane in which the earth moves around the sun. Likewise, if we project the position of sun each day throughout the year, we can see how it moves through the line, occupying different positions. In the picture, the sun is represented by the small yellow circle. We start with the Winter Solstice (0 degrees of Capricorn), South area of ​​decline. The sun is moving down to meet Ecuador in Vernal point (0 degrees of Aries), spring equinox. Then advance to the Summer Solstice, maximum declination North (0 ° Cancer) and descends from there, re-crossed the plane of Ecuador in the Autumn Equinox (0 degrees of Libra) descending back to Capricorn, completing the annual cycle. These peaks and troughs of the sun set over two parallel planes very important: the Tropic of Cancer and the Tropic of Capricorn. Both represent the highest latitudes the sun that reaches throughout the year. The Tropic of Cancer is at 23 º 27 'North Latitude and the Tropic of Capricorn at 23 º 27 'South latitude. When the sun reaches these latitudes, is said to be at the solstices. We astronomically located, therefore, the two Solstices (Cancer and Capricorn) and the two equinoxes (Aries and Libra). These points we mark the beginning of the season. Music (Music): Nacho Rouco Estévez Script, voiceover and production (Script, voiceover and production): Antonio Gonzalez Estevez Antonio Gonzalez Estevez © 2010, 2011.2012 Music Nacho Rouco Estévez © 2010, 2011, 2012