we looked at some pictures of increasing fuzziness to find out how far back into the distance we should ask zooite eyes to look for our next project, Hubble Space Telescope Zoo. This week the original plan was to look at some actual fuzzy blobs by Hubble - which is, contrary to appearances, Hubble's usual output! - but because poor Chris is laptopless, they will have to wait.
But the timing's excellent, because I would like to use this Object of the Day to expound on a little rant I indulged in for the She's an Astronomer
project yesterday. (Well, actually a couple of months ago in advance, but you know what I mean.
) I mentioned Jocelyn Bell-Burnell and Cecilia Payne-Gaposchkin as women who I believed were treated outrageously unfairly. We all know the story of Jocelyn Bell's supervisor being credited and winning the Nobel Prize for her discovery of pulsars. But Cecilia Payne-Gaposchkin
is lesser known - but made an amazing discovery about stars and how they shine.
Here's a lovely star, posted by Citisue and nominated by Mukund Vedapudi:587736979569901658
Cecilia Payne was studying physics at Cambridge in the early 1920s. But she gave up physics because the brilliant Ernest Rutherford
, who discovered so much about atoms, was so rude to her. It must have been clear that her ideas and discoveries would never be heard; Cambridge didn't then even give women degrees after they'd completed their studies. But when she switched to astrophysics, Arthur Eddington
was more welcoming, and in Marcus Chown's words, Payne became "fascinated with the problem of decoding the message in starlight". (This message is absorption
spectra, which reveal what types of atom are present in stars.)
Absorption and emission spectra tell us what element is present because of the way the electrons jump around, absorbing and emitting photons of light. The way they jump is unique to each type of atom. So it was known that the same types of atom as were present on the Earth were also present in the stars - but stars contained a lot more mysterious lines. Finally it was discovered that these extra lines weren't other atoms, but atoms with some electrons knocked off. (This is exactly what is happening with the Peas
!) The raging heat inside stars causes the atoms to shoot around so violently that the collisions knock off one, or two, or many electrons.
A physicist called Meghnad Saha
devised an equation
to predict what fraction of any element's atoms would be ionised and by how much, at any given temperature and density. Eddington had worked out the temperature and density of many stars around us. Payne was the first person to apply the Saha equation to them.
She had to go to Harvard to pursue her idea, because Cambridge did not accept women as PhD students at the time. She began her calculations and the proportions of elements seemed mostly to be the same as on Earth (for example lots of iron, some oxygen and silicon, only a very little gold and silver, etc). By finding out how much of each element was ionised, she could work out how much of the element there was altogether. But then something unexpected happened.
She found plenty of ionised hydrogen on the surface of the Sun. And only a tiny proportion of hydrogen atoms should be ionised. That meant that the Sun must be mostly hydrogen! Astronomers were convinced at the time, and many remained convinced until the 1950s, that the Sun was made mostly of iron. Henry Norris Russell
convinced Payne to retract her discovery and state in a journal that "the abundance of both hydrogen and helium in stars is improbably high and almost certainly not real". It wasn't until more evidence showed that Russell was forced to admit he had been mistaken, and Payne is not well known for her discovery. Nevertheless, her doctoral thesis, published in 1925, was described by an astronomer named Otto Struve as "undoubtedly the most brilliant Ph.D. thesis ever written in astronomy". She went on to make many other discoveries, such as on variable stars.
Posted by dthomas02 and nominated by Sophie 378:587730842066485352
We now know that the Big Bang created almost exclusively hydrogen and helium, and that these elements are what chiefly make up our Universe. We also know that the Sun shines because it fuses hydrogen into helium, though larger stars and red giants can fuse heavier elements too.
All of which shows, if you ask me, that everybody should be welcomed into astronomy.
Thanks for reading!