WaltarrrrrJan 2
Robert McNees

101 years ago, #OTD in 1925, Edwin Hubble announced that Andromeda and other spiral nebulae were definitely separate galaxies outside the Milky Way, in a paper read to an AAS meeting by H.N. Russell.

There was no doubt that the Universe was more than just our little island of stars.

Jan 2 at 2:14amIvory for Mac
Show threadRobert McNeesJan 2

Astronomers were divided on the issue; many still subscribed to the idea that everything they saw was within our Milky Way.

Hubble built on observations by Vesto Slipher, collaborated with Milton Humason, and relied on Henrietta Swan Leavitt’s Cepheid variable work to make his case. (2/n)

Show threadRobert McNeesJan 2
It seems hard to believe, but there are people alive today who were born into what many scientists thought was a much smaller universe. (3/n)
Show threadRobert McNeesJan 2

Until recently, my favorite examples of this were Jimmy Carter and Betty White.

President Carter was three months old when Hubble made his announcement. Betty White was about to turn three years old when we realized there are other galaxies. (4/n)

Show threadRobert McNeesJan 2
Hubble’s announcement — Other galaxies exist! Our Milky Way is just one of many! — was made on the third day of the 33rd Meeting of the American Astronomical Society, in a paper read by H.N. Russell. The meeting started on the 30th; maybe Hubble chose New Year’s Day for dramatic effect. (5/n)
Show threadRobert McNeesJan 2

For astronomers, the result likely wasn’t a sudden revelation. Hubble had been discussing his evidence with colleagues, and word had gotten around.

Many scientists were already sure of the result, and had been for years. They just needed irrefutable evidence. (6/n)

Show threadRobert McNeesJan 2

It’s hard to imagine the pre-Hubble view of the Universe, though it was just 101 years ago.

Before Hubble’s announcement, it was still a popular view among astronomers that the collection of stars making up our galaxy was Everything. (7/n)

Show threadRobert McNeesJan 2
Astronomer Harlow Shapley was, at the time, the leading proponent of the establishment view. He had long argued that spiral nebulae seen by astronomers — shapes any kid would now recognize as galaxies — were just dust clouds inside the Milky Way. (8/n)
Show threadRobert McNeesJan 2
But there had always been astronomers who suspected that the Milky Way was just one of many galaxies. This view goes at least as far back as Immanuel Kant’s “Universal Natural History and Theory of the Heavens,” which he published anonymously in 1755. (9/n)
Show threadRobert McNeesJan 2
Just five years before, in 1920, astronomer Heber Curtis argued against Shapley in the “Great Debate.” Curtis’s position, supported by a growing number of his colleagues, was that spiral nebulae were independent galaxies outside the Milky Way. (10/n)
Show threadRobert McNeesJan 2
It was the identification of Cepheid variable stars in M31 and other spiral nebulae that allowed Hubble to prove they were so far away that they must be outside the Milky Way. (11/n)
Show threadRobert McNeesJan 2

A Cepheid variable is a type of star whose brightness waxes and wanes over a period of time that tightly correlates with its maximum brightness.

Measure that period and you know its absolute brightness. Compare that to how bright it appears, and you can estimate its distance. (12/n)

Show threadRobert McNeesJan 2
This important property of Cepheid variable stars was discovered by astronomer Henrietta Swan Leavitt. It makes them “standard candles” (a term she coined) that we can reliably use for establishing distances to cosmologically nearby galaxies. (13/n)
Show threadRobert McNeesJan 2
Henrietta Swan Leavitt’s period-luminosity relationship for Cepheids is one of the first rungs on the “cosmic distance ladder,” the collection of methods used by astronomers to measure extragalactic distances. (14/n)
Show threadRobert McNeesJan 2

In the early morning hours of October 6, 1923, Edwin Hubble took a photo plate of M31 showing a Cepheid variable star. He originally mistook it for a nova - you can see where he has crossed out an “N” on the plate and excitedly replaced it with “VAR!” (15/n)

Image: Carnegie Observatories

Show threadRobert McNeesJan 2
Applying Henrietta Swan Leavitt’s period-luminosity relationship to subsequent observations, Hubble concluded that the distance to M31 was greater than reliable size estimates for the Milky Way. Therefore, it must be outside our galaxy. (16/n)
Show threadRobert McNeesJan 2

Hubble kept Shapley in the loop as he built the case for separate galaxies throughout 1924, alerting him to the discovery of Cepheid variables in M31, M33, and other spiral nebulae.

Shapley doubted Hubble at first. But he eventually relented in the face of growing evidence. (17/n)

Show threadRobert McNeesJan 2
Upon receiving one of Hubble's letters, Shapley remarked to doctoral student Cecilia Payne-Gaposchkin “Here is the letter that destroyed my universe.” (18/n)
Show threadRobert McNeesJan 2
Astronomically, January 1st is a meaningless date. It is an arbitrary reference point in a system based on the approximate orbital period of an otherwise unremarkable star that is perhaps only notable for having a life-bearing planet. (19/n)
Show threadRobert McNeesJan 2

But for those of us who reckon time by this system, today is the 101st anniversary of humanity taking a monumental step towards understanding our place in a Universe that is vast and puzzling, but ultimately knowable.

Happy New Year! (20/20)

Plot: Richard Powell
Annotations: Me

Show threadMedea Vanamonde 🏳️‍⚧️Jan 2
@mcnees did you ever read Damon Knight’s take on this, coupled with the discovery of expansion?
Show threadChuck DarwinJan 2
@mcnees
101 years ago, #OTD in 1925, Edwin Hubble announced that Andromeda and other spiral nebulae were definitely separate galaxies outside the Milky Way
@mastoreaderio unroll please
Show threadMasto ReaderJan 2

@cdarwin here's the unrolled thread: https://mastoreader.io?url=https%3A%2F%2Fc.im%2F%40cdarwin%2F115823118028210137

Next time, kindly set the visibility to 'Mentioned people only' and mention only me (@mastoreaderio). This ensures we avoid spamming others' timelines and threads unless you intend for others to see the unrolled thread link as well.

Thank you!

Masto Reader

Show threadCharlie StrossJan 2
@mcnees I'm convinced this phenomenon is where H. P. Lovecraft got his sense of cosmic dread from. During his lifetime, the postulated age of the universe increased by about 3 orders of magnitude but it's size expanded to a ridiculous degree (the implications of astronomical photography including Hubble's work arrived with a bang during his life).
Show threadRobert McNeesJan 2
@cstross Yes, and seeing the Newtonian worldview replaced with the advent of relativity and quantum mechanics! So many changes that left many people feeling very unmoored.
Show threadRobert McNeesJan 2
@cstross I read that something like 10% of people are really uncomfortable looking at photos of deep space — that it leaves them feeling disconnected and adrift. And that’s today, so they have at least some context for modern notions of our place in the Universe. I imagine being confronted by that during Lovecraft’s lifetime would be more like a full blown existential crisis.
Show threadRobert McNeesJan 2
@cstross Headlines like this one, from the NYT, ran in papers all over the world in 1919. It’s easy to imagine Lovecraft recoiling in horror.
Show threadLazarou Monkey Terror 🚀💙🌈Jan 2
@mcnees @cstross as a child I was terrified of the supercluster diagrams at the back of my big Space book. "It's too big!" my child brain thought.
Now I see the beauty of it all.
Show threadOrmanJan 2
@Lazarou @mcnees @cstross I am slightly disturbed whenever I'm reminded of the Bootes void, which is a region ~650 M ly across that contains only 60 galaxies instead of thousands.
Show threadLazarou Monkey Terror 🚀💙🌈Jan 2
@orman @mcnees @cstross I think I read an SCP set in there, it's just crying out for horror fiction.
Voids man......voids....
Show threadOrmanJan 2
@mcnees @cstross "more or less" is such a cute phrase in a headline, you'd never see it these days
Show threadRobert McNeesJan 2
@orman @cstross I love this weaselly phrase and use it all the time.
Show threadRobert McNeesJan 2
@cstross How can the stars be right, if they are not where they seemed or were calculated to be.
Show threadRoger BW 😷Jan 2
@mcnees @cstross Cosmic horror is a reaction to relativity, perceived as the last blow to the anthropocentric universe.
Show threadStrange QuarkJan 4

This blog post discusses the effect that this astronomical event had on Lovecraft's cosmology:
https://lovecraftianscience.wordpress.com/2017/09/16/lovecrafts-the-other-gods-part-1-earth-gods-and-other-gods/

@RogerBW @mcnees @cstross

Lovecraft’s “The Other Gods,” Part 1: Earth Gods and Other Gods

As previously mentioned data collected during the 29th of May 1919 eclipse was used to empirically confirm Einstein’s General Theory of Relativity and this had a substantial impact on Lovecraft’s v…

Lovecraftian Science
Show threadMedea Vanamonde 🏳️‍⚧️Jan 2

@mcnees @cstross

You know…he did have something akin to a nervous breakdown going to college with the degree goal of being an Astronomer. He stated he couldn’t do the math and it broke him. Tempted to go back thru his collected letters to see if the Hubble Volume blew his mind

Show threadEsslar2Jan 2
@mcnees @cstross That's odd, I find deep space photos to be wonderful. All I can do is wonder at the sheer vastness of it all. Mostly, I find these shots beautiful.
Show threadJohn Carlos BaezJan 2
@flyhigh @mcnees @cstross - I think a lot of people feel that way, too!
Show threadCharlie StrossJan 2
@mcnees IIRC that as a kid Lovecraft wanted to be an astronomer, but had depressive episodes and a near-breakdown in 1908 (aged 17-18): he never graduated high school. I suspect the rapid changes in cosmology circa 1900-1920 did a number on his headmeat.
Show threadMedea Vanamonde 🏳️‍⚧️Jan 2
@mcnees @cstross
That just blows my mind but I was exposed to the Expanding Universe and Relativity and Quantum Mechanics by my God Father during my 3rd and 4th year so it’s my UR reality grid. I look into the deepest space unfrozen by terror or awe but inspired by beauty and possibility.
Show threadOrmanJan 2

@mcnees @cstross quantum mechanics is so weird that it's really an exemplar for "go mad from the revelation or flee from the light," given that most modern people even now don't really grok the implications.

You can measure the outcomes of events that don't happen, and there's basic arguments to the effect that either linear causality is broken or the classical picture that particles have single-valued attributes is not merely straight-up wrong but unrecoverable

Show threadMichael GemarJan 2
@cstross @mcnees Yes, but I honestly think his racist views and concerns about the perceived loss of Western influence also contributed. He saw Anglo-Saxon men as the obvious pinnacle, but their place at the top was being radically changed by beings who he felt looked different and sounded unintelligible. Both his physical and socio-cultural universes were being overturned and his WASP heritage was shown to have little objective meaning.
Show threadRobert McNeesJan 2
@michaelgemar @cstross Oh yes, no question. I’m only speaking here about the scientific and philosophical impetus for his cosmic horror.
Show threadWeekend EditorJan 2

@cstross @mcnees

He was also living in New England during the depression.

There were scores of factory buildings and the like that were completely shut down, doors locked, and guarded. He might have wondered: if there's nothing much to steal inside those buildings, then why are they guarded? Maybe the guards aren't keeping buglars out, but keeping *something* inside!

Show threadCharlie StrossJan 2
@weekend_editor @mcnees Lovecraft was already 39 when the great depression started (1929). He died before WW2 began (unless you count Japan invading Manchuria, or the Anschluss).
Show threadWeekend EditorJan 2

@cstross @mcnees

Ok, thanks. I should have checked the dates.

Show threadDave FischerJan 2
@cstross @mcnees Photo of the moon I shot through the same telescope (at Brown University) that Lovecraft used as a teenager:
Show threadMedea Vanamonde 🏳️‍⚧️Jan 2
@cstross @mcnees it had a HUGEST effect on Olaf Stapledon, especially with Star Maker, which should be the Mythos of the Post Hubble Era, both the man and the space robot that carries his name
Show threadsimonbpJan 2
@mcnees It is just typical that VM Slipher first measured the blue shift of Andromeda, and then was confused as to why all the smaller nebulae were red.
Show threadOptimistic MoronJan 2
@mcnees
But the Earth is still flat, ain't it.
Show threadSörenJan 2
@mcnees Yepp.
And why #JWST is not called HSLST?
(Henrietta Swan Leavitt Space Telescope)
Show threadPaul MassonJan 2
@mcnees for the new year you might want to reply to your own posts to keep the feed more compact…
Show threadRobert McNeesJan 2
@paulmasson I’m not sure what you mean? On my end, each one of these is a reply to the previous post. Does it look different to you, or am I misunderstanding?
Show threadPaul MassonJan 2
@mcnees there is a way to keep replies to self out of public feeds. Perhaps “Quiet Public” mode. @johncarlosbaez knows how: perhaps he can enlighten us.
Show threadJohn Carlos BaezJan 2
@paulmasson @mcnees - "Quiet Public" would prevent replies to one's own posts from being announced as broadly as the original posts. However, I don't use that! I generally *want* each item in a series of posts to be loudly announced, since I figure people may read the first entry, then move on... and then, up to several hours later, I'll still be writing followups, which they'll miss unless I tap them on the shoulder.
Show threadPaul MassonJan 2
@johncarlosbaez @mcnees my apologies for bothering people. Carry on.
Show threadZhi Zhu 🕸️Jan 2

@mcnees

Your thread made me think of a recent news article.

NASA’s Largest Library Is Closing Amid Staff and Lab Cuts

Holdings from the library at the Goddard Space Flight Center, which includes unique documents from the early 20th century to the Soviet space race, will be warehoused or 👉 thrown out.👈
https://www.nytimes.com/2025/12/31/climate/nasa-goddard-library-closing.html

The Trump admn is just throwing away "books, documents and journals — many of them not digitized or available anywhere else." INSANE!

#Science #Books #News #US #USA

Show threadZhi Zhu 🕸️Jan 2

"The Trump admn is closing NASA’s largest research library... houses tens of thousands of #books, documents and journals — many of them not digitized or available anywhere else.

...some material would be stored in a government warehouse while the rest would be 👉 tossed away.👈
...

The shutdown of the #library... is part of a larger reorganization under the #Trump admn that includes the closure of... more than 100 #science and #engineering laboratories"
https://www.nytimes.com/2025/12/31/climate/nasa-goddard-library-closing.html

#Nazis #News #US

Show threadZhi Zhu 🕸️Jan 2

"The library closure on Friday follows the shutdown of seven other #NASA libraries ...

As of next week, only three — at the Glenn Research Center in Cleveland, the Ames Research Center in Mountain View, Calif., and the Jet Propulsion Laboratory in Pasadena, Calif. — will remain open."
https://www.nytimes.com/2025/12/31/climate/nasa-goddard-library-closing.html

[Trump & the #GOP are deliberately destroying #science in the US.]

#DonaldTrump #Trump #Politics #News #Ohio #California #Maryland #US #USA #UnitedStates

Research Library at NASA’s Goddard Space and Flight Center to Close Friday

Holdings from the library at the Goddard Space Flight Center, which includes unique documents from the early 20th century to the Soviet space race, will be warehoused or thrown out.

The New York Times