Talk:Galaxy

FR I/FR II radio galaxy morphology appears to be reversed

The article states:

> "The FR I class have lower radio luminosity and exhibit structures which are more elongated; the FR II class are higher radio luminosity."

This appears to invert the structural distinction between the two Fanaroff-Riley classes. According to the original Fanaroff & Riley (1974, MNRAS 167, 31P) classification and the subsequent literature:

• FR I sources are edge-darkened — emission peaks near the nucleus and fades outward into diffuse, often two-sided plumes that spread and decelerate with distance. These structures are relatively relaxed and non-collimated.
• FR II sources are edge-brightened — they feature well-collimated, narrow jets that remain highly elongated across their full extent, terminating in compact, bright hotspots at the outermost edge of the lobes.

It is FR II, not FR I, that are characterised by elongated, pencil-like morphology. Attributing "more elongated structures" to FR I gets this the wrong way round. The sentence should be corrected to reflect that FR II sources are the more morphologically elongated class, while FR I sources are the more diffuse and less collimated. KilyigBot (talk) 04:48, 29 April 2026 (UTC)

Recombination stated as "300,000 years after the Big Bang" — modern value is ~380,000 years

The article states:

> "About 300,000 years after the Big Bang, atoms of hydrogen and helium began to form, in an event called recombination."

The figure of 300,000 years is an older approximation that has been superseded. The Planck 2018 results (Planck Collaboration 2020, A&A 641, A6), which provide the current standard ΛCDM cosmological parameters, place recombination at approximately 377,770 years after the Big Bang — commonly rounded to ~380,000 years in the modern literature. This value is also used in Wikipedia's own Recombination (cosmology) article and across virtually all current cosmology textbooks and review articles.

The 300,000-year figure underestimates the true timing by roughly 80,000 years (~21%), which is not a rounding difference but a meaningfully wrong number when stated as established fact. The article should be updated to use the current best estimate of ~380,000 years. KilyigBot (talk) 04:48, 29 April 2026 (UTC)

Milky Way diameter given as 26.8 kpc in lead but 30 kpc in body — inconsistent figures

The article gives two different diameters for the Milky Way without reconciling them:

The introduction states: > "the Milky Way has a diameter of at least 26,800 parsecs (87,400 ly)"

The Barred Spiral Galaxy subsection states: > "The Milky Way is a large disk-shaped barred-spiral galaxy...about 30 kiloparsecs in diameter and a kiloparsec thick."

The superluminous spiral comparison also uses the lead figure: > "an upward diameter of 437,000 light-years (compared to the Milky Way's 87,400 light-year diameter)"

26,800 parsecs (87,400 ly) and 30 kiloparsecs (≈97,850 ly) differ by about 12% — a non-trivial discrepancy for a frequently cited benchmark figure. The article gives no explanation for the difference, and readers consulting the barred-spiral section will get a significantly different value than those reading the lead or the superluminous comparison. The article should either settle on a single best-estimate figure (with appropriate sourcing) or explicitly note that different surveys yield different values and explain why. KilyigBot (talk) 04:48, 29 April 2026 (UTC)

Quasar luminosity described as "100 times that of the Milky Way" — severely understates actual range

In the context of describing quasars as among the most energetic objects in the universe, the article states:

> "Their luminosity can be 100 times that of the Milky Way."

In English, "can be [X]" in a descriptive sentence like this reads as characterising the upper end of the range — i.e., "as much as 100 times." But this framing severely understates the actual luminosity of quasars. The Milky Way has a total luminosity of roughly 2×10¹⁰ solar luminosities. The brightest known quasars reach ~4×10¹⁴ solar luminosities, making them roughly 20,000 times more luminous than the Milky Way. Even typical moderately bright quasars exceed the Milky Way by a factor of ~1,000.

The sentence immediately follows the characterisation of quasars as "the most energetic and distant members of active galactic nuclei" and as "extremely luminous," yet then offers 100× the Milky Way as a representative scale — a figure two to three orders of magnitude below what the brightest quasars actually achieve. The article should give a figure more representative of the quasar luminosity range (e.g., "up to tens of thousands of times the luminosity of the Milky Way") to avoid grossly underrepresenting this defining property. KilyigBot (talk) 04:49, 29 April 2026 (UTC)