Posts tagged with astronomy

Johannes Kepler on whether his wife Susanna Reuttinger was destined as "The One":

Though all Christians … declar[e] solemnly that they enter into married life owing to a special divine management, ….

Was it divine Providence or moral guilt on my part which has torn my mind … in so many different directions and which led me listen to so many people … so divergent from each other?

Was it divine management that brought in all these persons and their actions?

As I believe, nothing extraordinary has happened to me. I believe that everyone of us has an experience similar to mine, not only once but very often. The difference is only that the others do not worry about it, as I do, they forget more easily and get over it more quickly than I do, or that they have more self-control and settle their unhappiness by themselves.

There is something wrong with my feelings; I stirred them up anew every day ….

As far as [Susanna] is concerned there is still the question of why, though she was destined for me, G-d permitted that she had six rivals in the course of one year?

Johannes Kepler: Life and Letters by Carola Baumgardt





M31 is a globular cluster located 25,100 light years away from Earth. It consists of 300,000 stars and is about 145 light years in diameter.

via intothecontinuum

hi-res




3D map of the large-scale distribution of dark matter, reconstructed from measurements of weak gravitational lensing with the Hubble Space Telescope.
via davidaedwards

3D map of the large-scale distribution of dark matter, reconstructed from measurements of weak gravitational lensing with the Hubble Space Telescope.

via davidaedwards


hi-res




Check out this portrayal of the computer from 1978.

  • Same concerns about privacy.
  • Same awe at its power (although the reel decks aren’t probably so familiar to most people anymore).
  • And computers, although they run a lot of stuff, like air control and banks, don’t show up much in your & my day-to-day lives, at least not obviously.

Says I 34 years later to you, “on” tumblr, which you may view with your smartphone.

(Source: topdocumentaryfilms.com)




Black Hole Fragmentation
Image Credit: Burkhard Zink, Nikolaos Stergioulas, Ian Hawke, Christian D. Ott, Erik Schnetter, and Ewald Muller

Black Hole Fragmentation

Image Credit: Burkhard Zink, Nikolaos Stergioulas, Ian Hawke, Christian D. Ott, Erik Schnetter, and Ewald Muller


hi-res



















At the local viewing of the transit of Venus, I asked an astronomer named Lisa how people noticed a planet going in front of the Sun in the first place. (Surely they weren’t just staring at the sun all day?)
She told me:
Edmund Halley predicted the transit of Venus. He died before being seen right, which seems sad, but we didn’t discuss that any further. Theory preceded observation. EDIT: Apparently Jeremiah Horrocks first wrote of the transit of Venus.
The first observed transit of Venus killed that last free parameter to allow scientists to figure out the absolute distance from Earth to the Sun. (Previously they’d only known relative distances between planets.)
I asked her the question I had formulated while watching Lawrence Krauss’ talk: how can you know, as in know-know, know know know, whether a star is bright or close?Her answer: astronomers make a lot of assumptions. (Ahhh, satisfaction.) In particular they assume that most stars are normal (Gaussian, not just usual). Well, that makes a lot of sense then.
Nowadays another telescope is being built (thank you, government) that will triple the range within which relevant things can be seen, so we will be able to see to the centre of the Milky Way galaxy (and equal distance in the opposite direction) — and do so very precisely.So precisely that we will be able to measure parallax — the difference in how stars appear in winter versus summer, when we’re on opposite sides of the Sun — and obtain precise knowledge of where many, many stars are. (Tripling length means roughly times 3³ volume, so more like 20-30 times more stars’ positions will be known.)
Now this is the kicker in your Popperian dirtsack. Ancient Greeks had the right theory (heliocentric solar system) but discarded it on the basis of experimental evidence!Never preach to me about progress-in-science when all you’ve heard is a one-liner about Popper and the communal acceptance of general relativity. Especially don’t follow it up by saying that “science" marches toward the Truth whilst "religion" thwarts its progress.According to Astronomer Lisa, it’s not true that the Greeks simply thought they and their Gods were at the centre of the Universe because they were egotistical. They reasoned to the geocentric conclusion based on quantitative evidence. How? They measured parallax. (Difference in stellar appearance from spring to fall, when we’re on opposite sides of the Sun.) EDIT: More by @rmathematicus, suggested by @sc_k. How did heliocentrism eventually triumph in the Renaissance?Given the insensitivity of their measurement tools at the time, the stars didn’t change positions at all when the Earth moved to the other side of the Sun. Based on that, they rejected the heliocentric hypothesis.If the Earth actually did move around the Sun, then the stars would logically have to appear different from one time to another. But they remain ever fixed in the same place in the Heavens, therefore the Earth must be still (geocentric).
I always told this story to myself as the gradual removal of anthropocentrism from the natural order. First we learn we’re not the centre of the Universe, then we’re not the only Galaxy, we’re not the only species that falls in love, we’re evolved by chance like everyone else, and so on. But that story is wrong. It doesn’t fit this bit of the history of ideas and I bet it doesn’t fit other bits of history either. I need a new story.

At the local viewing of the transit of Venus, I asked an astronomer named Lisa how people noticed a planet going in front of the Sun in the first place. (Surely they weren’t just staring at the sun all day?)

She told me:

  1. Edmund Halley predicted the transit of Venus. He died before being seen right, which seems sad, but we didn’t discuss that any further. Theory preceded observation. EDIT: Apparently Jeremiah Horrocks first wrote of the transit of Venus.
  2. The first observed transit of Venus killed that last free parameter to allow scientists to figure out the absolute distance from Earth to the Sun. (Previously they’d only known relative distances between planets.)
  3. I asked her the question I had formulated while watching Lawrence Krauss’ talk: how can you know, as in know-know, know know know, whether a star is bright or close?

    Her answer: astronomers make a lot of assumptions. (Ahhh, satisfaction.) In particular they assume that most stars are normal (Gaussian, not just usual). Well, that makes a lot of sense then.
  4. Nowadays another telescope is being built (thank you, government) that will triple the range within which relevant things can be seen, so we will be able to see to the centre of the Milky Way galaxy (and equal distance in the opposite direction) — and do so very precisely.

    So precisely that we will be able to measure parallax — the difference in how stars appear in winter versus summer, when we’re on opposite sides of the Sun — and obtain precise knowledge of where many, many stars are. (Tripling length means roughly times 3³ volume, so more like 20-30 times more stars’ positions will be known.)
  5. Now this is the kicker in your Popperian dirtsack. Ancient Greeks had the right theory (heliocentric solar system) but discarded it on the basis of experimental evidence!

    Never preach to me about progress-in-science when all you’ve heard is a one-liner about Popper and the communal acceptance of general relativity. Especially don’t follow it up by saying that “science" marches toward the Truth whilst "religion" thwarts its progress.

    According to Astronomer Lisa, it’s not true that the Greeks simply thought they and their Gods were at the centre of the Universe because they were egotistical. They reasoned to the geocentric conclusion based on quantitative evidence. How? They measured parallax. (Difference in stellar appearance from spring to fall, when we’re on opposite sides of the Sun.) EDIT: More by @rmathematicus, suggested by @sc_k. How did heliocentrism eventually triumph in the Renaissance?

    Given the insensitivity of their measurement tools at the time, the stars didn’t change positions at all when the Earth moved to the other side of the Sun. Based on that, they rejected the heliocentric hypothesis.

    If the Earth actually did move around the Sun, then the stars would logically have to appear different from one time to another. But they remain ever fixed in the same place in the Heavens, therefore the Earth must be still (geocentric).

I always told this story to myself as the gradual removal of anthropocentrism from the natural order. First we learn we’re not the centre of the Universe, then we’re not the only Galaxy, we’re not the only species that falls in love, we’re evolved by chance like everyone else, and so on. But that story is wrong. It doesn’t fit this bit of the history of ideas and I bet it doesn’t fit other bits of history either. I need a new story.




If you put your hand up in the night, away from L.A., and look at a dark spot of the sky the size of a dime—with a large enough telescope, you could see 100,000 galaxies there.

Stars explode once every 100 years per galaxy. So in that little region with 100,000 galaxies, on a given night you’ll see ten stars explode.

The universe is huge, and old, and rare things happen all the time.

Lawrence Krauss

minute 17:30 of this lecture

(Source: youtube.com)