Barbara Ryden

@bsryden

Writer of astrophysics textbooks, servant to cats

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Barbara Ryden@bsryden· 5h

Isn't it grand? (Agnostic/Presbyterian speaking here.) Of course, I walked 280 km, so my response to the cathedral was somewhat dulled by exhaustion.

Assorted tired pilgrims in front of the cathedral in Santiago de Compostela

Barbara Ryden@bsryden· 13d

International Cat Day falls on a #Caturday this year! That means it is time to party like a cat.

An orange tabby cat lounges upside down on the lap of a mere human.

Barbara Ryden@bsryden· 16d

I love that Hoyle/Redman exchange!

"A star is basically a pretty simple structure."
"You'd look pretty simple, Fred, at a distance of ten parsecs."
Fred Hoyle (1915-2001) and Roderick Redman (1905-1975)
at Cambridge Observatory [1954]

Barbara Ryden@bsryden· 24d

A cat-approved book!

A cat sniffs a copy of Physics for Cats.

Barbara Ryden@bsryden· Jul 14

January 1921: NGC 584 is inconceivably distant. VP-elect has faith in America's moral fiber. July 2026: NGC 584 is at a distance of ~20 megaparsecs. Current VP is not regarded as an authority on moral fiber.

New York Times, Wednesday, January 19, 1921, page 6. Headlines are: "COOLIDGE HAS FAITH IN OUR MORAL FIBRE" and "DREYER NEBULA NO. 584 INCONVEIVABLY DISTANT"

Barbara Ryden@bsryden· Jul 12

Orange tabby cat (Finn) lies lengthwise on the sofa. Gray and white cat (Trim) lies crosswise.

Barbara Ryden@bsryden· Jun 22

That sphinx has seen a lot. (Including, but not limited to, a small plush hippopotamus named Epsilon).

Small plush hippo rests between the forelegs of the sphinx statue at Miramare Castle.

Barbara Ryden@bsryden· Jun 21

Since the cats have anti-parallel spins, they can both occupy the ground state. (Since they are cats, they are seldom in an excited state.)

Two cats engage in cat napping, side by side.

Barbara Ryden@bsryden· Jun 14

Seen from certain angles, at occasional moments, the OSU campus is lovely.

An egret flies over Mirror Lake, on the main campus of the™ Ohio State University. A fountain plays at the far end of Mirror Lake.

Barbara Ryden@bsryden· Jun 7

Trim and Finn are recovering after their Caturday night party.

A gray and white cat (named Trim) and an orange tabby cat (named Finn) are sprawled side by side on an end table next to a sofa.

Barbara Ryden@bsryden· May 13

Because it is sooo hard nowadays to get a good woodcut artist to illustrate your paper.

Barbara Ryden@bsryden· May 10

Make it the first stop on your next visit to Bath! (Because of course there will be a next visit; you've been bitten by the Bath Bug.)

Fairly large astronomer standing next to a very petite dress once worn by Caroline Herschel.

Barbara Ryden@bsryden· Apr 28

Apparently, I am an author. It says so, right on my label.

An astronomer is wearing a space-cat-themed shirt. A nametag is clipped to the shirt, reading "Barbara Ryden AUTHOR"

Barbara Ryden@bsryden· Apr 11

Although my Friday lecture was on quasars, I decided to spread some Moon joy in the cover slide for the lecture. (The students seemed to tolerate the digression.)

Cover slide for the Friday, April 10 lecture of Ast 2142 (Black Holes) at The Ohio State University. The slide includes two images: on the right, the "Earthset" photo from the Artemis II mission; on the left, the "Earthrise" image from the Apollo 8 mission, cropped to match "Earthset."

Barbara Ryden@bsryden· Mar 14

Happy #Caturday! Trim and Finn have each others' back, in a fine example of feline solidarity.

A gray and white cat (named Trim) and an orange tabby cat (named Finn) are sleeping back-to-back on a fleece blanket.

Barbara Ryden@bsryden· Feb 20

Same, Misty. Same.

Orange tabby cat. Underneath the cat is a lap.

Barbara Ryden@bsryden· Jan 24

Happy #Caturday. If you are in the path of a winter storm, Trim and Finn recommend that you keep warm.

A gray and white cat and an orange tabby cat are snuggled together atop a fleece blanket.

Barbara Ryden@bsryden· Jan 8

It is not strictly required, when attending a meeting of the American Astronomical Society, to pose in front of the big AAS sign. However, I couldn't resist the opportunity. #aas247

Barbara Ryden (wearing a nametag saying "Barbara Ryden") stands in front of a large sign saying "AAS".

Barbara Ryden@bsryden· Jan 1

I haven't quite decided if this is the ideal epigraph for chapter 8. Too Byronic, do you think, or just Byronic enough?

Epigraph for chapter 8 of Astrophysical Gas Dynamics:

When Newton saw an apple fall, he found
In that slight startle from his contemplation -
'Tis said (for I'll not answer above ground
For any sage's creed or calculation) -
A mode of proving that the earth turn'd round
In a most natural whirl, called "gravitation";
And this is the sole mortal who could grapple,
Since Adam, with a fall or with an apple.

Lord Byron, "Don Juan," Canto X [1823]

Barbara Ryden@bsryden· Dec 26

Happy Boxing Day from Finn the cat!

An orange tabby cats sits inside a cardboard box.

Barbara Ryden@bsryden· Dec 21

Happy #Solstice! I hope everyone in the northern hemisphere is keeping warm (preferably with the help of a cat).

Orange tabby cat, sitting comfortably on a human lap

Barbara Ryden@bsryden· Dec 13

I hope you are having a well-groomed #Caturday (perhaps with a little help from a friend).

A gray and white cat (Trim) licks the head of an orange tabby cat (Finn).

Barbara Ryden@bsryden· Nov 10

Oh, darn! This means I missed this year's "Revolution in Science" Day. (Headline in the Times of London from Nov. 7, 1919 about the same eclipse results.)

REVOLUTION IN SCIENCE.
NEW THEORY OF THE UNIVERSE.
NEWTONIAN IDEAS OVERTHROWN.

Yesterday afternoon in the rooms of the Royal Society, at a joint session of the Royal and Astronomical Societies, the results obtained by British observers of the total eclipse of May 29 were discussed.
[Times, November 7, 1919, page 12]

Barbara Ryden@bsryden· Oct 28

Why didn't geologists take Snider- Pelligrini seriously in 1858? Partly because of the lack of a known mechanism for plate techtonics. Partly because of his involvement in a wonky French plan to colonize Texas.