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How Space-Time Works When You Look At The Stars

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Channel: Seeker
Categories: Physics   |   Science  
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We're used to looking at everything around us unfolding in real time. But when we look at the stars, were actually looking at the past. We arent seeing the stars, or really anything in the universe, as they currently are. Were seeing things as they were.
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Huge thank you to Chabot Space & Science Center for all of their help with this video. Check them out here:

The most important point you need to remember is that light travels at a constant speed, which means that it takes time to get anywhere. So, if you look up at the Big Dipper, the stars are anywhere from 79 to 125 light-years away. That means that what youre seeing is really the light that left the star 79 or more years ago. When you look up and see the moon, thats what it looked like 1.3 seconds ago. Same idea with the planets.

It works in reverse too. If you looked at Earth through a super powerful telescope from a galaxy 65 million light years away, you would see Earth as it was 65 million years ago, or around the time that the T-rex went extinct.

Thinking about the speed of light isnt a new concept. There is some evidence that scholars in fourteenth century India were exploring the speed of sunlight. They thought of light as a sort of wind. And though they couldnt prove anything concretely, when converted into modern units, the ancient calculation came surprisingly close to the actual speed of light.

#spacetime #constellations #astronomy #astrology #science #seeker

High-Redshift Astronomy - Taylor Hutchinson
I work with galaxies that existed less than one billion years after the Big Bang, at redshifts of z 5. To give an idea of how long ago that is, current cosmology places the age of the Universe at approximately 13.7 billion years old. These young galaxies are so distant that their rest-ultraviolet (rest-UV) emission lines have been redshifted into the near-infrared (NIR). To measure the rest-UV spectrum of these sources requires sensitive NIR spectrographs on some of the world's largest telescopes. We call this redshift range the Epoch of Reionization.

Redshift and Hubbles Law
In 1929, Edwin Hubble announced that almost all galaxies appeared to be moving away from us. In fact, he found that the universe was expanding - with all of the galaxies moving away from each other. This phenomenon was observed as a redshift of a galaxy's spectrum. This redshift appeared to be larger for faint, presumably further, galaxies. Hence, the farther a galaxy, the faster it is receding from Earth.

What is the universe expanding into?
When we think of space in everyday life, we don't think of it as something which is capable of stretching. Space, to us, just seems like something which is there, and which everything else in the universe exists within. But according to Einstein's theory of general relativity, space isn't really as simple as our common sense tells us. If we want to understand the actual way that the universe functions, we need to find some way to incorporate Einstein's ideas into our mental picture and imagine space as a more complicated entity which is capable of doing things like bending and stretching.

You can probably point to the Big Dipper, Orion's Belt, and your astrological sign in the stars.
But what would the constellations look like from another solar system? And will any of Orions stars ever become black holes? In Seeker Constellations, we'll explain the science of the universes most famous stars and dive into the culturally significant stories behind them. Most importantly, well provide a guide to where you can see these incredible constellations for yourself!
Seeker empowers the curious to understand the science shaping our world. We tell award-winning stories about the natural forces and groundbreaking innovations that impact our lives, our planet, and our universe.

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