Planetary Positions according to JPL Data

In summary, the conversation discusses an Excel program that is supposed to provide Keplerian data for planets based on a given date. However, it does not work properly. The data is obtained from the NASA JPL website and includes information such as a semi-major axis, eccentricity, inclination, and more. The conversation also mentions the calculation of Julian Date and J2000 and how this information is used in the JPL data. The True Anomaly equation is mentioned, but there are flaws in the logic. The conversation ends with the attachment of a file meant to demonstrate the issue.
  • #1
Philosophaie
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Attached is a Excel program given a Date it will susposedly give the Keplarian data for each of the Planets. It does not work. The Data is given from Nasa JPL:

http://ssd.jpl.nasa.gov/txt/p_elem_t2.txt

Julian Date and J2000 are calculated. J2000 or just J is plugged into the JPL data:

a-Semi-Major Axis
e-Eccentricity
i-inclination
ML-Mean Longitude
LP-Longitude of the Perihelion
N-Longitude of the Ascending Node

Calculated from the above are:

MA-Mean Anomaly
EA-Eccentric Anomaly
w-Argument of the Perihelion
r-Planet Radius from the Sun
v-True Anomaly
Equ-Equinox-On Mar 21 looking thru the Sun the angle it makes with the projected Perihelion

The True Anomaly gives the approximate answer for all dates but my logic is flawed if you use the equation:

vActual=Equ+N+w+v

I have worked a long time on this. Any input would be much appreciated!
 

Attachments

  • Planetary Data from JPL Horizons.xls
    47 KB · Views: 384
Last edited:
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  • #2
I gave you the wrong file. The other is too big for the Physics Forum. The point I was trying to make is that from the angle looking thru the sun at the Vernal Equinox or 3-31 added together vActual=Equ+N+w+v yields a somewhat correct answer not taking into account of the inclination, i.
 
  • #3
Here is the file meant to show.
 

Attachments

  • Planetary Positions with JPL Data at Equinoxes & Solstices.xls
    46.5 KB · Views: 240

1. What is JPL data and why is it important for studying planetary positions?

JPL data refers to the data collected and analyzed by the Jet Propulsion Laboratory (JPL) of NASA. This data includes precise measurements of the positions and movements of planets, moons, and other celestial bodies in our solar system. It is important for studying planetary positions because it provides accurate and updated information that can help scientists understand the dynamics and behavior of these objects.

2. How is JPL data collected and verified?

JPL data is collected using various methods, including ground-based telescopes, spacecraft missions, and radar observations. The data is then processed and verified through rigorous scientific analysis and calculations. It is also cross-checked with data from other sources to ensure its accuracy.

3. Can I access JPL data for my own research?

Yes, JPL provides access to its data through various online databases and tools, such as the HORIZONS system and the Solar System Dynamics website. However, a basic understanding of astronomy and data analysis is recommended for using this data effectively.

4. How often is JPL data updated?

JPL data is updated regularly, with some data being updated daily and others being updated periodically. The frequency of updates depends on the type of data and the availability of new observations or measurements.

5. Can JPL data be used to predict future planetary positions?

Yes, JPL data can be used to make accurate predictions about the future positions of planets and other celestial bodies. This is possible because the data includes precise information about the positions, orbits, and movements of these objects, which can be used to make calculations and projections for the future.

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