Lecture 26: Telescopes

How old is the Earth? In this lecture I review the ideas of cyclic and linear time, and how this determines whether or not the question of the age of the Earth is meaningful. I then review various ways people have tried to estimate the age of the Earth, starting with historical a ...  Show more

What is the interior structure of the Earth? We will start our exploration of the Solar System with our home planet Earth. This lecture discusses the interior structure of the Earth, introducing the idea of differentiation, how geologists map the interior of the Earth using seism ...  Show more

There was a time when science and religion worked in harmony, as two parts of a celestial design. Astrologer and philosopher Johannes Kepler oversaw this marriage of theory and belief when he proposed the revolutionary laws of planetary motion in the early 17th century. Amidst pe ...  Show more

Melvyn Bragg and guests discuss the flow of particles from the outer region of the Sun which we observe in the Northern and Southern Lights, interacting with Earth's magnetosphere, and in comet tails that stream away from the Sun regardless of their own direction. One way of defi ...  Show more

Melvyn Bragg and guests discuss the pioneering Danish astronomer Tycho Brahe (1546 – 1601) whose charts offered an unprecedented level of accuracy.In 1572 Brahe's observations of a new star challenged the idea, inherited from Aristotle, that the heavens were unchanging. He went o ...  Show more

The sun is out, the weather is warm, and summer school is in session! Neil deGrasse Tyson, co-host Matt Kirshen, and astrophysicist Charles Liu answer fan-submitted questions on mathematics, the Big Bang, the laws of physics, neutrinos, relativity, Pluto, the smell of the Milk ...