Discussion Overview
The discussion revolves around the timing of Earth's perihelion in 2012, specifically the discrepancies in reported times from various sources. Participants are examining the definitions and models used to determine the exact moment Earth reaches its closest point to the Sun, with a focus on the implications of different reference points such as the Earth and the Earth-Moon barycenter.
Discussion Character
- Debate/contested
- Technical explanation
Main Points Raised
- One participant states that Earth reached its perihelion on January 4, 2012, at 10:59 PM EST, but notes conflicting accounts regarding the exact timing.
- Another participant provides a specific time of January 5, 2012, at 00:33 (TT) as a reference for perihelion.
- A third participant seeks clarification on whether the time mentioned refers to January 5, 2012, at 00:00:33 (TT) and translates to Ephemeris Time.
- One participant clarifies that they meant 33 minutes after midnight (TT) and cites JPL Horizons for the Earth-Sun range rate change.
- Another participant references the Barycenter Earth-Moon model from JPL Horizons, indicating a different time of January 4, 2012, at 3:00 (TT) for the smallest heliocentric range and questions the discrepancy with the January 5 time.
- Further clarification is provided regarding the use of the Earth-Moon barycenter versus the Earth itself, emphasizing that perihelion is defined by the Earth's position relative to the Sun.
Areas of Agreement / Disagreement
Participants express disagreement regarding the exact timing of Earth's perihelion, with multiple competing views presented based on different models and reference points. The discussion remains unresolved.
Contextual Notes
There are limitations regarding the definitions of perihelion based on different reference points (Earth vs. Earth-Moon barycenter) and the implications of timing precision, which are not fully reconciled in the discussion.