Talk:Galactic year

Relevance

I cant say I've ever heard this term outside of this article , at least in astronomy circles, and the whole thing has a suspicious whiff of original research. Perhaps the term doesnt really rise to the standards of prominence wikipedia requires Duckmonster (talk) 01:00, 16 September 2022 (UTC)

no offense

But someone has this backwards. A Galactic Year is a period of time, a long period of time, but a period of time. First, you have oceans and then you have life. The sequence in the present article says that it took less time for oceans to appear than life. The list is backwards. 76.211.231.2 (talk) 18:47, 29 March 2008 (UTC)

No the dates are offset from the birth of the sun. Like we do with Anno Domini —Preceding unsigned comment added by 212.248.196.12 (talk) 13:07, 20 June 2008 (UTC)

Why not offset from the Big Bang? It's not as if we don't know when that happened. So the Earth would form at 40 GY, the present would be about 60 GY, etc. The galaxy formed less than a GY after the Big Bang. --arkuat (talk) 05:56, 6 January 2010 (UTC)

I have made some changes to the time scale according to what You suggest, and removed the note on the obvious mistakes which were there, before.Hans Dunkelberg (talk) 14:49, 15 January 2011 (UTC)

I propose making the epoch the present day (with unit as "galactic years ago"), as the current list gives implausible precision to recent events, e.g. "19.999 GY: Appearance of modern humans" implies that modern humans appeared 4.499775 billion years after the sun formed (i.e. accurate to within 225 000 years, even though we're unsure whether a galactic year is 225 or 250 million years). cmɢʟee'τaʟκ'maιʟ 19:25, 12 December 2011 (UTC)

The time scale still doesn't make sense

I appreciate all of the work being put into this, but the time scale still doesn't measure correctly with the Earth's known age. According to the current page, the Sun is only 18.4 galactic years old, but we know the earth to be 4.54 billion years aka 20 galactic years old. Either the math is off or the Earth formed before the Sun. I am presuming the former since the latter would be a pretty shocking discovery. — Preceding unsigned comment added by 69.255.19.206 (talk) 05:24, 12 March 2013 (UTC)

With almost total confidence the math is wrong on both accounts. The method used to evaluate the age of Earth is based on radioactive decay, and it takes a huge leap in faith assuming that this decay ratio has remained constant for billions of years, that Earth is a closed system (which is false), and that there does not exist any other processes that could alter the concentration of isotopes in a more influential way. The Sun could perfectly turn out to be younger than Earth if there exists a "rejuvenation" process available to stars but not to planets. — Preceding unsigned comment added by 185.31.153.179 (talk) 01:09, 24 November 2015 (UTC)

Our age

Just think how human beings as individuals count their age by the number of times they revolve the sun. We should think about our age as a species being counted by our revolutions around the galaxy. That is until we are able to travel out of our galaxy. —Preceding unsigned comment added by 99.48.146.49 (talk) 20:19, 24 June 2010 (UTC)

Heading toward what in a Galactic Orbit?

Perhaps, it is not what is heading toward us that we should be concerned about, but rather, what we are spiraling to. Is it possible that the Milky Way goes by something...or thru something during this orbit and the Earth just so happens to be in vincinity of something turbulant? Is this the reason for so many past disruptions and extinctions? —Preceding unsigned comment added by Mahovictor (talk • contribs) 14:22, 18 October 2010 (UTC)

GY is not a reasonable abbreviation for Galactic Year

While there is no SI unit for Year, the prefix of an uppercase G to any unit is commonly understood to mean Giga, or 10^9 times the value to follow. A lowercase g would be much more suitable. --173.33.56.239 (talk) 16:57, 26 February 2011 (UTC)

Support Unless someone can turn up a reliable source of its use, I'd spell it out in full. cmɢʟee'τaʟκ'maιʟ 19:19, 12 December 2011 (UTC)

delete Unless its a term in actual use (with citations!) then its original research. Don't use an abreviation at all. Duckmonster (talk) 01:02, 16 September 2022 (UTC)

I think that there is a mistake in the intro

Shouldn't it be (as long as the article talks in general and not specifically about the Milky Way): "is the duration of time required for a Star and it's planetary system or a Solar System like our own to orbit once around the center of a Galaxy.

What are your thoughts on this? (And you can rephrase my paragraph above the way you want, but I just want to give you what the mistake is and what I am trying to say).--Megahmad (talk) 01:18, 26 August 2013 (UTC)

Agreed. We don't ned to use the term "solar system". Any point will do, so surely the best one is the sun?

Galactic Year will eventually shorten?

I know the talk page isn't really the place the discuss the subject, and this counts as original research/synthesis, so I probably shouldn't bring this up, but in the interest of just provoking thought, I just wanted to bring up that since current prevailing theory is that all galaxies, including our own, contain at their center a supermassive black hole that is constantly pulling in stars, our galactic year is constantly shortening by a relatively infinitesimal amount. 74.67.17.69 (talk) 22:34, 7 March 2014 (UTC)

missing events in "Timeline of the universe and Earth's history in galactic years"

The orogenic phases are missing from this timeline, e.g.

• Alpine orogeny
• Cadomian Orogeny
• Variscan orogeny
• Cadomian Orogeny

In german WP there is this: de:Vorlage:Linkbox Geogebirgsbildung. User:ScotXW^t@lk 12:18, 21 November 2015 (UTC)

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"12 galactic years from now The Earth's magnetic field shuts down [7] and charged particles emanating from the Sun gradually deplete the atmosphere [8]"

The citations given for this listing don't actually have anything to do with the claims being made.

To support the claim that it is knowable when (even if) Earth's geodynamo will fail, a citation is given about some minor observation of Mars. This ignores the fact that we have literally no idea how either dynamo system actually works (or worked, in the case of Mars), or how long it will or won't last. No conclusion about the failure of Mars' dynamo has any bearing on the future of Earth's. Even claiming it will fail before the planet itself is rendered uninhabitable is a claim made with absolutely no sound reasoning or evidence behind it. Attaching a specific eon to the claim is insane.

To support the claim that this will then result in the gradual stripping away of Earth's atmosphere (which would be self-evident if it actually happened), a citation is given about the depletion of the ozone layer. That's non sequitur at best. --71.239.186.126 (talk) 21:17, 24 October 2018 (UTC)

Thanks. I removed the line. ★NealMcB★ (talk) 22:36, 2 July 2020 (UTC)

Remove table? Or at least add conventional times as well?

The table seems tacked on to the article with little justification. Few if any of the cites probably list these times in galactic years. If it remains, we should at least give times in years also to facilitate checking the entries.★NealMcB★ (talk) 22:38, 2 July 2020 (UTC)

Definition only

This page should intentionally just be a stub. State the definition, then stop.

The galactic year should be defined and that's it. It really isn't used by astronomers in the same way that a tropical year or calendar year is. It is not a unit and there is no standard symbol for it. The value itself isn't even all that well known. I've never seen it used for cosmological timelines anywhere besides here.

The content after the definition was someone's good faith contribution to a page that was probably overlooked. Adding on a hypothetical application is not the purpose of a Wikipedia page (imho). 2603:7000:9500:DD00:24E2:6612:999:F588 (talk) 01:11, 17 July 2024 (UTC)

The introduction is basically descriptive and should be retained, but the timeline table is at best only approximations which are not identified as ranges, nor are they consistent with generally accepted values. The timeline section should be deleted. Pmarshal (talk) 17:12, 27 August 2024 (UTC)