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arxiv: 2606.27055 · v1 · pith:MDRKNGW3new · submitted 2026-06-25 · 🌌 astro-ph.EP · astro-ph.IM· astro-ph.SR· cs.CG· cs.SE

Solarsystem: A Validated Lightweight Python Package for Planetary Positions and Solar-Lunar Event Calculations

Ioannis Nasios This is my paper

Pith reviewed 2026-06-26 03:04 UTC · model grok-4.3

classification 🌌 astro-ph.EP astro-ph.IMastro-ph.SRcs.CGcs.SE
keywords planetary positionssolar systemPython packageanalytical modelsephemeridessolar eventslunar eventscoordinate transformations
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The pith

A lightweight Python package delivers planetary positions and solar-lunar events through analytical models without external ephemeris files.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper introduces solarsystem, a dependency-free Python package that computes heliocentric and geocentric positions for major planets, selected dwarf planets, Chiron, and the Moon. It also handles sunrise, sunset, moonrise, moonset, and lunar illumination, plus coordinate transformations and optional precession corrections. Algorithms rely on analytical models rather than downloaded datasets, making the tool portable and efficient. Validation against JPL DE440 ephemerides over multiple bodies and long time spans shows mean longitude deviations of 0.44 arcminutes and latitude deviations of 0.16 arcminutes, with solar-lunar event timings accurate to a few minutes and illumination estimates off by about 0.2 percent. The package is installable via PyPI with source and notebooks on GitHub.

Core claim

The implemented analytical models produce heliocentric and geocentric positions for the major planets, selected dwarf planets, the Centaur Chiron, and the Moon, together with solar and lunar event calculations, while supporting coordinate transformations and an optional precession correction; when tested against JPL DE440 using Skyfield, these yield mean planetary longitude and latitude deviations of approximately 0.44 and 0.16 arcminutes over extended intervals, with solar-lunar timing differences of only a few minutes and lunar illumination differences of approximately 0.2 percent.

What carries the argument

Analytical models for planetary positions and solar-lunar events that avoid external ephemeris datasets, with optional precession correction to switch between reference frames.

If this is right

  • Users can run planetary calculations on any machine without downloading large ephemeris files.
  • Solar and lunar event times remain usable for planning within a few minutes of reference solutions.
  • Lunar illumination estimates support applications that tolerate 0.2 percent error.
  • Coordinate transformations and precession options allow flexible reference-frame choices in one library.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The same analytical approach could support lightweight astronomy tools in resource-constrained environments such as embedded devices or educational software.
  • Extending the models to additional minor bodies would broaden coverage while preserving the no-external-data property.
  • Integration with visualization libraries could enable quick generation of sky charts for citizen-science projects.

Load-bearing premise

The chosen analytical models stay accurate enough over the tested time spans and bodies without needing external data or numerical integration.

What would settle it

Direct position comparison at an epoch well outside the validated interval, such as year 3000, that produces longitude or latitude deviations substantially larger than 1 arcminute.

Figures

Figures reproduced from arXiv: 2606.27055 by Ioannis Nasios.

Figure 1
Figure 1. Figure 1: Solarsystem Heliocentric planet position calculation example [PITH_FULL_IMAGE:figures/full_fig_p008_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Planet Heliocentric position difference without precession correction discrepancies remains relatively small, typically remaining below one degree with an average of approximately 0.35 degrees for the period between 1950 and 2050. The observed behavior strongly suggests that the dominant systematic component of the positional discrepancy originates from the omission of epoch-dependent pre￾cession correctio… view at source ↗
Figure 3
Figure 3. Figure 3: Planets position around the Sun on 11/06/2026 temporal analyses of solar and lunar phenomena. An example rise/set and lunar illu￾mination calendar generated using the package is presented in [PITH_FULL_IMAGE:figures/full_fig_p014_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: June 2026 calendar for Athens, Greece. Sunrise/ [PITH_FULL_IMAGE:figures/full_fig_p015_4.png] view at source ↗
read the original abstract

This paper presents solarsystem, a validated lightweight and dependency-free Python package for planetary positions and solar-lunar event calculations. The package provides heliocentric and geocentric positions for the major planets, selected dwarf planets, the Centaur Chiron, and the Moon, together with sunrise, sunset, moonrise, moonset, and lunar illumination calculations. Additional functionality includes coordinate transformations between commonly used astronomical reference systems. The implemented algorithms employ analytical models that avoid reliance on external ephemeris datasets, resulting in a portable and computationally efficient solution suitable for a broad range of astronomical applications. An optional precession correction model is included, enabling calculations either in a precession-corrected reference frame or in a fixed epoch framework, depending on user requirements. The numerical performance of solarsystem was evaluated against the JPL DE440 planetary ephemerides using the Skyfield framework as a reference. Validation experiments spanning multiple bodies and extended temporal intervals demonstrate good agreement with the reference ephemerides, with mean planetary longitude and latitude deviations of approximately 0.44 and 0.16 arcminutes, respectively. Additional validation of solar and lunar event calculations yielded timing differences of only a few minutes relative to the reference solutions, while lunar illumination estimates differed by approximately 0.2%. The package can be installed directly through PyPI while the source code, documentation, validation notebooks and example workflows are publicly available through the project repository in https://github.com/IoannisNasios/solarsystem.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

0 major / 2 minor

Summary. The manuscript presents solarsystem, a lightweight, dependency-free Python package implementing analytical models for heliocentric and geocentric positions of the major planets, selected dwarf planets, Chiron, and the Moon, plus solar-lunar event calculations (sunrise/sunset, moonrise/moonset, lunar illumination) and coordinate transformations. An optional precession correction is included. Validation against JPL DE440 via Skyfield reports mean planetary longitude and latitude deviations of ~0.44 and ~0.16 arcmin, solar/lunar event timing differences of a few minutes, and lunar illumination differences of ~0.2%. The package is available via PyPI with public code, documentation, and validation notebooks on GitHub.

Significance. If the reported agreement holds, the package provides a portable, computationally efficient alternative to full ephemeris libraries for applications where external datasets are impractical. Public release of validation notebooks and example workflows supports reproducibility. The use of independent reference ephemerides (DE440) for validation avoids circularity and directly tests the accuracy of the analytical models over the claimed domains.

minor comments (2)
  1. [Abstract] Abstract: The validation summary should specify the exact time intervals, number of bodies tested, and outlier handling to allow readers to evaluate the robustness of the mean deviation figures (0.44/0.16 arcmin).
  2. The manuscript would benefit from a table or figure breaking down deviations by individual body and time span rather than reporting only aggregate means.

Simulated Author's Rebuttal

0 responses · 0 unresolved

We thank the referee for their positive evaluation of the manuscript and their recommendation to accept.

Circularity Check

0 steps flagged

No significant circularity

full rationale

The paper implements known analytical models for planetary positions and validates their output directly against the independent external reference JPL DE440 (via Skyfield). The reported mean deviations (0.44/0.16 arcmin) and event timing differences are empirical comparisons to this external benchmark, not reductions of the package's own fitted parameters or self-citations. No derivation chain, uniqueness theorem, or ansatz is load-bearing; the central claim is a straightforward accuracy test against an outside ephemeris and therefore self-contained.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

The package rests on standard analytical planetary theory from prior literature; no new free parameters, axioms, or invented entities are introduced in the abstract.

pith-pipeline@v0.9.1-grok · 5812 in / 984 out tokens · 47808 ms · 2026-06-26T03:04:04.286087+00:00 · methodology

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Reference graph

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