Continuing the discussion on the topic of Earth's orbit

Continuing the discussion on the topic of Earth's orbit, that took place at ABAA yesterday, Jayanth has sent this post for further discussion.

Table gives the calculations of earths orbit assuming same is elliptical. If this is verified by observations (Red marked values), then it a proof that the orbit of earth is not circular but elliptical.

Observational proof of Earth's Elliptical orbit
Planet	Earth
Mean period	365.25
Earth year	1
Eccentricity	0.017
Mean AU	1
AU @ Perigee	0.983
AU @ Apogee	1.017
Year Perigee	0.974609
Year Apogee	1.025608
Earth Year Perigee	355.9758
Earth Year Apogee	374.6033
Angular velocity of earth due to rotation / day	0.2500000
Angular Velocity Perigee / day in degrees	1.011305
Angular Velocity Apogee / day in degrees	0.961017
Angular velocity Perigee translated to time sec	242.7131
Angular velocity Apogee translated to time sec	230.644
Time difference in sky revolving due to earth's elliptical rotationSec	12.06915
Angular velocity if earth orbit is circular	0.985626
Angular velocity translated to time sec Circular orbit	236.5503
Mean circular time - Perigee time	-6.162805
Mean circular time - Apogee time	5.906347

How to observe ?

Fix a telescope pointed to a bright star of say 3rd magnitude. Lock the movements of telescope. Use a highly accurate stop watch say +/- 0.1 sec per day which is easily available. Align cross hair position on eye piece in North - South and East-West direction. Start stop watch once star centers and is on North - South cross hair. Leave the setup till next day without disturbance (Better inside the room to take care of the weather, wind, heat..............). Next day at the same time observe the same star drifting in the eye piece. Stop the stop watch once the star is on North - South Cross hair. Note the time.

It is expected to have a timing of 86400-236.5503 = 86163.4497 sec if circular.

If elliptical, depending on the position of the earth around the sun, time will vary. For Perigee it should be 86400-242.7131 = 86157.2869 sec and for Apogee it should be 86400-230.644 = 86169.356 sec

In reality, we should go the other way by observational data over the year, work back to find the Eccentricity of the orbit......... ;-))

Happy Observation

Regards

Jayanth.B

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