Showing posts with label X-rays. Show all posts
Showing posts with label X-rays. Show all posts

April 19 - Happy Birthday, Kim Weaver

Posted on April 19, 2020


April 19, 1964: Kim Weaver is born in West Virginia.

April 19, 1969: Age 5, little Kim is impressed by photographs of planets, galaxies, and the Moon. She asks about the 300-foot antenna dish located nearby and is interested in the answer - it is listening to radio signals from space!


July 20, 1969: Still 5, Kim is thrilled to watch Apollo 11 crew land on - and eventually walk on! - the Moon.

She decides right then and there that she wants to be a scientist and work for NASA.

Flash forward about 20 years: Dr. Kim Weaver has graduated with a B.S. in physics and a M.S. and Ph.D. in astronomy.

And now: Weaver is an astrophysicist and professor. She works for NASA, just as she hoped, so long ago - mostly focusing on x-ray astronomy.



What, you may ask, is x-ray astronomy?

With ordinary telescopes, scientists study the universe via visible light, which is the most familiar part of the electromagnetic spectrum.





 Radio telescopes like the dishes that inspired Weaver as a child allow scientists to study the universe via radio waves, which have much longer wavelengths than those of visible light. 






X-ray telescopes are used to study the universe with x-rays, which have much shorter wavelengths. 




This is a comparison of M82 galaxy with visible light (left) and x-rays (right): 



Here is a photo of a neutron star in the Crab Nebula. The x-ray light is shown in purple, ultraviolet light in blue, visible light in green, infrared light in yellow, and radio light in red: 









National Library Week in the U.S. - April 19 through 25


(The 2020 theme of National Library Week is “Find Your Place at the Library” - a theme chosen long before anyone could imagine a global pandemic would close libraries-the-physical-buildings. However, libraries are still open for business online. 

 Here are some things you can access: 
"...ebooks, movies, music, video games, virtual storytimes and activities, and so much more — all from the the comfort of your home.")





(Third Saturday of April)

Plan ahead:


Check out my Pinterest boards for:
And here are my Pinterest boards for:

Posted by at No comments:
Labels: , , , , , ,

November 5, 2009

On this day in 1895, X-rays were discovered!

 NOTE: I see some sources claim that the discovery day is November 8, 1895.

Wilhelm Conrad Roentgen is credited with the discovery and naming of X-rays. He called the new, invisible ray “X” to stand for unknown. However, in some countries (including Roentgen's native Germany), X-rays are called Roentgen rays. (He strongly objected.) Whatever we call them, these “rays” are a form of electromagnetic radiation, like light, ultraviolet light, and microwaves.

The first picture of a human body part ever taken with X-rays is the hand of Roentgen's wife. Roentgen published his scientific paper on the new form of radiation in December, 1895, and he showed other scientists the X-ray of the hand; the medical benefit of seeing through flesh to bone or metal was immediately apparent, and X-rays began to be used for broken bones and gunshot wounds just a few months later, in early 1896. American inventor Thomas Edison came up with a fluoroscope that became widely used to take X-rays. (Edison gave up X-ray research, however, when one of his glassblowers got cancer. We now know that energetic forms of electromagnetic radiation can be dangerous, and we are careful to shield X-ray technicians and patients from exposure as much as possible.)


Quick Quiz
1. Which of these, like X-rays, is a form of electromagnetic
radiation?
Radio waves Water waves Sound waves

2. How fast do X-rays travel?
Instantly Speed of sound Speed of light

3. Which is the best shield against X-rays?
Water Wood Lead

4. Which emits the most X-rays?
Ordinary stars Black holes Gas planets

5. X-rays are like gamma rays in that both are
high-frequency, short-wavelength forms of
radiation. X-rays come from...
electrons. nuclei. neutrons.

Answers:

1) radio waves 2) speed of light 3) lead 4) black holes 5) electrons


How X-Ray Machines Work

This diagram shows a very simplified version of an X-ray machine. The X-rays are able to travel through the skin, muscle, and hospital gown and hit the fluorescent screens, and this exposure makes this part of the screen light. However, the X-rays are to a great extent blocked by bone or metal, so those areas of the X-ray picture remain dark.

You can do a safe demonstration analogous to taking an X-ray picture by putting a window screen over a box or clean patch of pavement. Put a cardboard shape on top of the screen, then carefully scatter sand over the entire box or screened area. When the cardboard and screen are removed, the area that had been blocked by the cardboard is almost entirely free of sand, and this area makes a kind of negative “picture” of the cardboard shape.


Crystallography

X-rays are used to determine the arrangement of atoms in a solid such as a protein. Check out the beautiful images available when you type “Crystallography” into Google Image search.



Credit: the U.S. Department of Energy Human Genome Program http://www.ornl.gov/hgmis



Extra: on Credit

Roentgen is credited with the discovery of X-rays, but he is not the first person to notice this form of radiation; he is the first to systematically study it and publish a paper on it, and he is certainly the one that named this radiation X-rays. He made his discovery by accident when using a cathode ray tube in his lab. Other scientists who worked with cathode ray tubes, since the invention of Crooke's tubes in 1875, had noticed the effect of some invisible energy on such things as photographic plates. Some did not investigate at all, and others, such as Nikola Tesla, did careful experiments but did not end up creating a catchy name and a medical demand for the phenomenon. Roentgen earned a Nobel Prize for his work with X-rays.
Posted by at 1 comment:
Labels: , ,
Subscribe to: Posts (Atom)