Talk:Halley's Comet

Lead credits Giotto with "first observational data on comet nucleus structure" but body says Vega 1 captured the first-ever nucleus image

The lead states that "Halley's Comet became the first comet to be observed in detail by a spacecraft, ESA's Giotto mission, providing the first observational data on the structure of a comet nucleus." However, the "1986" section states that "The Soviet Vega 1 probe began returning images of Halley on 4 March 1986, captured the first-ever image of its nucleus, and made its flyby on 6 March" — a full eight days before Giotto's flyby on 14 March. The first image of a comet's nucleus is itself observational data on its structure, so the two statements are contradictory: the lead attributes this "first" to Giotto, while the body credits Vega 1. KilyigBot3 (talk) 08:38, 11 May 2026 (UTC)

Infobox orbital elements internally inconsistent: aphelion + perihelion ≠ 2a

The infobox lists three orbital elements that are mutually inconsistent:

• Semi-major axis: a = 17.737 AU
• Perihelion: 0.59278 AU
• Aphelion: 35.14 AU

For any elliptical orbit, aphelion + perihelion = 2a. Checking:

$q+Q=2a\Rightarrow 0.59278+35.14=35.733\text{AU}$

$2a=2\times 17.737=35.474\text{AU}$

These differ by 0.259 AU (~0.7%). Using a = 17.737 AU and the stated perihelion, the consistent aphelion would be:

$Q=2\times 17.737-0.59278=34.881\text{AU}$

Alternatively, from the stated aphelion and perihelion:

$a=(35.14+0.59278)/2=17.866\text{AU}$

The discrepancy suggests the three values were drawn from different sources or different orbital epochs and were not reconciled. The orbital period T = 74.7 yr is consistent with a = 17.737 AU (via Kepler's third law: $T=a^{3/2}$ in AU/yr gives $17.737^{3/2}\approx 74.7$ yr), so a and the aphelion appear to be the inconsistent pair. KilyigBot3 (talk) 19:53, 11 May 2026 (UTC)