Concepts in astronomy
In astronomy, magnitude is a unitless measure of the brightness of an object in a defined passband, often in the visible or infrared spectrum, but sometimes across all wavelengths. An imprecise but systematic determination of the magnitude of objects was introduced in ancient times by Hipparchus.
14 episodes
Episodes in this category also belong to the following categories:
Black Holes
Melvyn Bragg discusses Black Holes, the dead collapsed ghosts of massive stars.
12 April 2001
Featuring: Martin Rees, Jocelyn Bell Burnell, Martin Ward
Comets
Melvyn Bragg and his guests discuss comets, the 'dirty snowballs' of the solar system which orbit the sun.
17 January 2013
Featuring: Monica Grady, Paul Murdin, Don Pollacco
Cosmic rays
Melvyn Bragg and his guests discuss cosmic rays, the mysterious high-energy particles that constantly bombard Earth.
16 May 2013
Featuring: Carolin Crawford, Alan Watson, Tim Greenshaw
Dark Energy
Melvyn Bragg discusses the recently discovered, and mysteriously named, 'dark energy' which may make up 70% of the universe.
17 March 2005
Featuring: Martin Rees, Carolin Crawford, Roger Penrose
Dark matter
Melvyn Bragg and his guests discuss dark matter, the mysterious and invisible substance that is believed to make up most of the universe.
12 March 2015
Featuring: Carolin Crawford, Gresham Professor of Astronomy Carlos Frenk, Anne Green
Eclipses
Melvyn Bragg and guests discuss the progress in our understanding of eclipses from the ancient world onwards and how their predictability illuminates historical records and myths.
31 December 2020
Featuring: Carolin Crawford, Frank Close, Lucie Green
Exoplanets
Melvyn Bragg and guests discuss exoplanets, planets detected outside our solar system.
3 October 2013
Featuring: Carolin Crawford, Don Pollacco, Suzanne Aigrain
Galaxies
Melvyn Bragg and guests discuss the galaxies; spread out across the void of space like spun sugar, but harbouring in their centres super-massive black holes.
29 June 2006
Featuring: John Gribbin, Carolin Crawford, Robert Kennicutt
Gravitational Waves
Melvyn Bragg and guests discuss Gravitational Waves, mysterious phenomena that ripple the fabric of space-time.
17 May 2007
Featuring: Jim Al-Khalili, Carolin Crawford, Sheila Rowan
The Age of the Universe
Melvyn Bragg and his guests discuss a question which has obsessed cosmologists for millennia: how old is the Universe?
3 March 2011
Featuring: Martin Rees, Carolin Crawford, Carlos Frenk
The Death of Stars
Melvyn Bragg and guests discuss how so much in the Universe, and much of our understanding of it, depends on changes in stars as they die after millions or billions of stable years
9 June 2022
Featuring: Martin Rees, Carolin Crawford, Mark Sullivan
The Life of Stars
Melvyn Bragg discusses the life cycle of stars. They are born among vast swirls of gas and dust and they die in stunning explosions.
27 Mar 2003
Featuring: Paul Murdin, Janna Levin, Phil Charles
The Planets
Melvyn Bragg discusses our knowledge of the planets in both our and other solar systems. What causes them to form and what is the likelihood of there being another with properties similar to Earth’s?
27 May 2004
Featuring: Paul Murdin, Hugh Jones, Carolin Crawford
The Universe's Origins
Melvyn Bragg examines the way thinking about the origins of the universe changed in the 20th century. Are we any closer to knowing whether other worlds exist and how our planet came into being?
20 May 1999
Featuring: Martin Rees, Paul Davies