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 | 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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