31 May 2010

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

No comments:

Post a Comment