Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: bobdihi on 16/06/2018 08:19:57
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Is there any variations in Earth's orbit around the Sun? Meaning the path taken by the Earth around the Sun from year to year. If any , how much they differ?
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Is there any variations in Earth orbit around the Sun? Meaning the path taken by the Earth around the Sun from year to year. If any , how much they differ?
See ... https://en.wikipedia.org/wiki/Milankovitch_cycles#Orbital_shape_(eccentricity) (https://en.wikipedia.org/wiki/Milankovitch_cycles#Orbital_shape_(eccentricity))
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Is there any variations in Earth's orbit around the Sun?
Even within a single year, there is some variation in Earth's orbit, due to the eccentricity (slight egg-shape) of Earth's orbit.
- At the closest point in its orbit, Earth is 147 million km from the Sun, around January 4th.
- At the farthest point in its orbit, Earth is 152 million km from the Sun, 6 months later.
- Due to the inverse square law, the intensity of solar radiation is about 7% greater in January than July.
In practice, it means that Northern hemisphere seasons are a little less extreme than you would expect from Earth's tilt
- And Southern hemisphere seasons are a little more extreme.
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Is there any variations in Earth orbit around the Sun? Meaning the path taken by the Earth around the Sun from year to year. If any , how much they differ?
See ... https://en.wikipedia.org/wiki/Milankovitch_cycles#Orbital_shape_(eccentricity) (https://en.wikipedia.org/wiki/Milankovitch_cycles#Orbital_shape_(eccentricity))
To illustrate this quote from the link,
"The Earth's rotation around its axis, and revolution around the Sun, evolve over time due to gravitational interactions with other bodies in the solar system. The variations are complex, but a few cycles are dominant.", we can look at these two charts for Keplerian Elements for two different time ranges.
First for 1800AD-2050AD
https://ssd.jpl.nasa.gov/txt/p_elem_t1.txt
This lists the rate of change in the Earth's average distance from the Sun as increasing by a rate of 0.00000564 AU(~844 km)/century, and the eccentricity decreasing by 0.00004392/century.
and then for 3000BC-3000AD
https://ssd.jpl.nasa.gov/txt/p_elem_t2.txt
Over which period the average distance decreases at a rate of 0.00000003 AU(~4.5 km)/century, and the eccentricity decreases at a rate of 0.00003661/century ( ~83% the rate it decreases at during the 1800 AD- 2050AD period.)