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Ask an astronomer: What makes neutron stars so special?

Astrophysicist Michelle Thaller talks ISS and why NICER is so important.

MICHELLE THALLER: I'm an astrophysicist and one of the things that I have been really impressed with with the International Space Station, some of the most amazing and innovating and strange experiments today are actually located on the space station. It's, of course, a wonderful platform to look at a lot of stuff because you're up above the atmosphere, you're up in space and you can both look out into space and you can also look back down at our home planet the Earth.

One of the things that makes it a challenge to actually use it as, for example, an observatory with telescopes is that the space station swings around a lot so you have to be able to actually stabilize the image and what you're looking at, especially if you're working on the space station. But to me certainly one of the most amazing discoveries of the last year has come out of the space station experiment called NICER, that's the acronym. It stands for the Neutron star Interior Composition Explorer so NICER. And NICER it's actually a camera that looks at x-ray light. So, this is very, very high energy light and luckily for us this light does not get through the atmosphere. There are x-rays coming from space all the time and they would be very harmful to us but they're absorbed by the air in the Earth's atmosphere. Of course that means if you want to study x-rays coming from space you need to get up above the atmosphere and the space station is. Now, NICER was specifically designed to look at a very interesting type of dead star called a neutron star. And a neutron star is the remnants when a very massive star, a star that might have been 10, 20, 50 times the mass of the sun violently dies and explodes. And incredibly the core of the star is usually still intact after that because the core became so compressed in that explosion that it holds together as a giant ball of atoms basically. Neutron stars are only about ten miles across. They have the density of one big atomic nucleus and that means that if you had a teaspoon full of this material, this neutronium, that teaspoonful would have about as much mass as Mount Everest. So, a ten mile ball every little bit of it is that dense and not only that these things spin hundreds of times a second. They are wonderful. They are real monsters. The gravity around them is so intense, it's not a black hole but it's sort of natures next best thing. The gravity is so intense that light is actually bent around these objects. And one of the most amazing things that we did with NICER recently is we used data coming in from x-rays from these hot dense little balls to actually map the surface and see where parts were hotter than others. And that was very challenging to do because when you actually took an image, and this wasn't a simple image it was constructed out of many different observations, but what you're actually doing is you're not only seeing the front of that object but you're seeing the back of the object too because light is bending around the object. Gravity is so strong it actually warps light around so that you see the front and the back of the object at once.

And so, to make this map we had to actually sort of deconvolve which parts were from the front of this neutron star and which parts were from the back. Now, another thing that is just kind of wonderful is that these things spin around as I said hundreds of times a second. And as they do they emit burst of radiation every time they make a spin. And that's a very, very accurate clock, they're actually more accurate than most clocks here on Earth. And what we're doing now is we're trying to use those bursts of radiation coming hundreds of times a second to create a timing device all around the Earth. And what that will be is something like a system of GPS satellites, global positioning satellite. So, all of those tiny little signals each one is a little different, each neutron star spins at a slightly different rate and you can triangulate exactly where you are based on these blips that are coming at you from the neutron stars. And what that means is that we'll have a GPS system we can use anywhere in the galaxy. So, even our deep space probes you get far away from earth like say you want to go out to Saturn, we don't have any GPS satellites out by Saturn; it's hard to know exactly where you are and we still use the positions of stars around the spacecraft to do that. But what if you had a GPS system that will never go out, it will never go down, it will stay accurate for many, many centuries if not millennia and it's not based on anything technological, anything human driven it's based on rotating dead stars in the sky?
Conceivably we could go to any of these planets that we're discovering, more than 4000 planets now around other stars, and using the same system we would know exactly where we are. So, you might not think about it but right now the space station at this moment is taking data from hundreds, if not thousands, of these spinning dead stars and we're using it to find our place in the galaxy.

  • Being outside of Earth's atmosphere while also being able to look down on the planet is both a challenge and a unique benefit for astronauts conducting important and innovative experiments aboard the International Space Station.
  • NASA astrophysicist Michelle Thaller explains why one such project, known as NICER (Neutron star Interior Composition Explorer), is "one of the most amazing discoveries of the last year."
  • Researchers used x-ray light data from NICER to map the surface of neutrons (the spinning remnants of dead stars 10-50 times the mass of our sun). Thaller explains how this data can be used to create a clock more accurate than any on Earth, as well as a GPS device that can be used anywhere in the galaxy.

Live on Tuesday | Personal finance in the COVID-19 era

Sallie Krawcheck and Bob Kulhan will be talking money, jobs, and how the pandemic will disproportionally affect women's finances.

Women who go to church have more kids—and more help

Want help raising your kids? Spend more time at church, says new study.

Culture & Religion
  • Religious people tend to have more children than secular people, but why remains unknown.
  • A new study suggests that the social circles provided by regular church going make raising kids easier.
  • Conversely, having a large secular social group made women less likely to have children.
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Bubonic plague case reported in China

Health officials in China reported that a man was infected with bubonic plague, the infectious disease that caused the Black Death.

(Photo by Centers for Disease Control and Prevention/Getty Images)
  • The case was reported in the city of Bayannur, which has issued a level-three plague prevention warning.
  • Modern antibiotics can effectively treat bubonic plague, which spreads mainly by fleas.
  • Chinese health officials are also monitoring a newly discovered type of swine flu that has the potential to develop into a pandemic virus.
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Leonardo da Vinci could visually flip between dimensions, neuroscientist claims

A neuroscientist argues that da Vinci shared a disorder with Picasso and Rembrandt.

Christopher Tyler
Mind & Brain
  • A neuroscientist at the City University of London proposes that Leonardo da Vinci may have had exotropia, allowing him to see the world with impaired depth perception.
  • If true, it means that Da Vinci would have been able to see the images he wanted to paint as they would have appeared on a flat surface.
  • The finding reminds us that sometimes looking at the world in a different way can have fantastic results.
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Education vs. learning: How semantics can trigger a mind shift

The word "learning" opens up space for more people, places, and ideas.

Future of Learning
  • The terms 'education' and 'learning' are often used interchangeably, but there is a cultural connotation to the former that can be limiting. Education naturally links to schooling, which is only one form of learning.
  • Gregg Behr, founder and co-chair of Remake Learning, believes that this small word shift opens up the possibilities in terms of how and where learning can happen. It also becomes a more inclusive practice, welcoming in a larger, more diverse group of thinkers.
  • Post-COVID, the way we think about what learning looks like will inevitably change, so it's crucial to adjust and begin building the necessary support systems today.
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