School of Physics & Astronomy


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Black Holes

Black holes are a favourite of both science fiction and science fact. What are they though, and should we be afraid of them? How big would the Earth be if we wanted to make it into a black hole, and how big can they get? Is their terrible reputation really warranted?

Presenters: Omar Almaini
Duration: 00:06:37

Hubble Constant

The Hubble constant tells us how quickly the universe is expanding and is usually quoted in really odd units. It also isn't actually a constant, and took many years to work out a reliable value for, and involved many arguments. Some groups thought it was around 100, others thought it was nearer to 50, and today we think it is about 67. So everyone wins!

Presenters: Michael Merrifield
Duration: 00:03:24

Creating the Elements

Where do all the elements we know and love come from? The universe started with mostly just hydrogen and helium, so where is oxygen, iron, nitrogen, gold, silver and particularly carbon come from? Here we discuss some of the ways elements are made. Supernovas explode into the story.

Presenters: Omar Almaini
Duration: 00:06:12

Dark Matter

It's an embarrassing fact that only relatively recently, we discovered that 95% of the universe is missing. Dark Energy makes up about 70% of the universe, but here we are concerned with Dark Matter which makes up about 27% of the universe. Put another way there is about 5 times as much dark matter as there is regular matter. Unfortunately we can't see it, although we are searching for it. So here we look at why we think it exists and what it might be? Featuring a chocolate pie!

Duration: 00:11:43

Star Classification

Classifying stars - it's the first step we need to start our understanding of stars. Why do we give the star types such weird letters to classify them? Spectroscopic sequence helped analyse the different types in the late 1800's. Featuring the Harvard "computer", Annie Jump Cannon, one of the first woman astronomers, and who came up with the basic classification we use today after simplifying previous classifications.

Duration: 00:07:57

Tycho and the Toilet

Tycho Brahe was the last of the great night sky observers. Using only his eyes and a very precise measuring device, he pushed the art of visible observation without any telescope to its limits. He was clearly an eccentric character who owned a moose, had a notable lack of nose, and came to his end probably due to a lack of toilet access. These are only some of the idiosyncrasies of his life!

Duration: 00:05:22

World's Biggest Telescope

Telescopes are the lifeblood of astronomers. Why do they want bigger and bigger telescopes. Why do they always want them in such exotic locations. We are currently building the biggest telescope in the world of truly enormous proportions.

Duration: 00:08:32


Redshift is a measure of how fast objects in the distant universe are moving away from you. It is often used in astronomy as a measure of distance, because of Hubble's law which relates the redward shift in wavelength of the spectra of very distant objects to their distance and their epoch in the history of the universe.

Duration: 00:08:37

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