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The Earth's orbit approximates an ellipse. Eccentricity measures the departure of this ellipse from circularity. The shape of the Earth's orbit varies between nearly circular (theoretically the eccentricity can hit zero) and mildly elliptical (highest eccentricity was 0.0679 in the last 250 million years). [7] Its geometric or logarithmic mean ...
Orbital forcing is the effect on climate of slow changes in the tilt of the Earth's axis and shape of the Earth's orbit around the Sun (see Milankovitch cycles).These orbital changes modify the total amount of sunlight reaching the Earth by up to 25% at mid-latitudes (from 400 to 500 W/(m 2) at latitudes of 60 degrees).
One complete orbit takes 365.256 days (1 sidereal year), during which time Earth has traveled 940 million km (584 million mi). [2] Ignoring the influence of other Solar System bodies, Earth's orbit, also called Earth's revolution, is an ellipse with the Earth–Sun barycenter as one focus with a current eccentricity of 0.0167. Since this value ...
The ancient Greek astronomer Hipparchus noted the apsidal precession of the Moon's orbit (as the revolution of the Moon's apogee with a period of approximately 8.85 years); [4] it is corrected for in the Antikythera Mechanism (circa 80 BCE) (with the supposed value of 8.88 years per full cycle, correct to within 0.34% of current measurements). [5]
e, eccentricity of Earth's (Sun's) orbit or Moon's orbit. and 1/2 accounts for the average of the sine squared waveform, () accounts for the average distance cubed of the Sun or Moon from Earth over the entire elliptical orbit, [34] and ε (the angle between the equatorial plane and the ecliptic plane) is the maximum value of δ for the Sun and ...
[13] [14] Similarly, Earth has an effective temperature of 255 K (−18 °C; −1 °F), [14] but a surface temperature of about 288 K (15 °C; 59 °F) [15] due to the greenhouse effect in our lower atmosphere. [5] [4] The surface temperatures of such planets are more accurately estimated by modeling thermal radiation transport through the ...
A value of 0 is a circular orbit, values between 0 and 1 form an elliptic orbit, 1 is a parabolic escape orbit (or capture orbit), and greater than 1 is a hyperbola. The term derives its name from the parameters of conic sections, as every Kepler orbit is a conic section.
There are two primary debris fields: the ring of objects in GSO and the cloud of objects in low Earth orbit (LEO). The Kessler syndrome, also known as the Kessler effect, [1] [2] collisional cascading, or ablation cascade, is a scenario proposed by NASA scientists Donald J. Kessler and Burton G. Cour-Palais in 1978.