Earth orbit shape driver#
Earth orbit shape series#

It was last at its maximum tilt about 10,700 years ago and will reach its minimum tilt about 9,800 years from now. These effects arenвЂ™t uniform globally - higher latitudes receive a larger change in total solar radiation than areas closer to the equator.Д®arthвЂ™s axis is currently tilted 23.4 degrees, or about half way between its extremes, and this angle is very slowly decreasing in a cycle that spans about 41,000 years. Larger tilt angles favor periods of deglaciation (the melting and retreat of glaciers and ice sheets). The greater EarthвЂ™s axial tilt angle, the more extreme our seasons are, as each hemisphere receives more solar radiation during its summer, when the hemisphere is tilted toward the Sun, and less during winter, when it is tilted away. Over the last million years, it has varied between 22.1 and 24.5 degrees with respect to EarthвЂ™s orbital plane. Obliquity вЂ“ The angle EarthвЂ™s axis of rotation is tilted as it travels around the Sun is known as obliquity. Because variations in EarthвЂ™s eccentricity are fairly small, theyвЂ™re a relatively minor factor in annual seasonal climate variations. The total change in global annual insolation due to the eccentricity cycle is very small. Currently, EarthвЂ™s eccentricity is near its least elliptic (most circular) and is very slowly decreasing, in a cycle that spans about 100,000 years. When EarthвЂ™s orbit is at its most elliptic, about 23 percent more incoming solar radiation reaches Earth at our planetвЂ™s closest approach to the Sun each year than does at its farthest departure from the Sun. That means each January, about 6.8 percent more incoming solar radiation reaches Earth than it does each July. The difference in the distance between EarthвЂ™s closest approach to the Sun (known as perihelion), which occurs on or about January 3 each year, and its farthest departure from the Sun (known as aphelion) on or about July 4, is currently about 5.1 million kilometers (about 3.2 million miles), a variation of 3.4 percent. As eccentricity decreases, the length of our seasons gradually evens out. These variations affect the distance between Earth and the Sun.Д®ccentricity is the reason why our seasons are slightly different lengths, with summers in the Northern Hemisphere currently about 4.5 days longer than winters, and springs about three days longer than autumns. Eccentricity measures how much the shape of EarthвЂ™s orbit departs from a perfect circle. Over time, the pull of gravity from our solar systemвЂ™s two largest gas giant planets, Jupiter and Saturn, causes the shape of EarthвЂ™s orbit to vary from nearly circular to slightly elliptical. LetвЂ™s take a look at each (further reading on why Milankovitch cycles can't explain Earth's current warming here).Д®ccentricity вЂ“ EarthвЂ™s annual pilgrimage around the Sun isnвЂ™t perfectly circular, but itвЂ™s pretty close. The direction EarthвЂ™s axis of rotation is pointed, known as precession.The angle EarthвЂ™s axis is tilted with respect to EarthвЂ™s orbital plane, known as obliquity and.The shape of EarthвЂ™s orbit, known as eccentricity.These cyclical orbital movements, which became known as the Milankovitch cycles, cause variations of up to 25 percent in the amount of incoming insolation at EarthвЂ™s mid-latitudes (the areas of our planet located between about 30 and 60 degrees north and south of the equator). Specifically, he examined how variations in three types of Earth orbital movements affect how much solar radiation (known as insolation) reaches the top of EarthвЂ™s atmosphere as well as where the insolation reaches.

Earth orbit shape driver#

A century ago, Serbian scientist Milutin Milankovitch hypothesized the long-term, collective effects of changes in EarthвЂ™s position relative to the Sun are a strong driver of EarthвЂ™s long-term climate, and are responsible for triggering the beginning and end of glaciation periods (Ice Ages). Others are human-produced, like growing and harvesting crops, musical rhythms or economic cycles.Д¬ycles also play key roles in EarthвЂ™s short-term weather and long-term climate. Some are natural, such as the change of the seasons, annual animal migrations or the circadian rhythms that govern our sleep patterns. There are hundreds of different types of cycles in our world and in the universe.

Earth orbit shape series#

Our lives literally revolve around cycles: series of events that are repeated regularly in the same order.