1. The delicate glowing band of the Milky Way, viewed edge-on in the night sky. We're looking sideways at a flattened disc of stars - our galaxy. Seen from outside, the Milky Way has a spiral structure. It is a family of 150 billion stars. Our Sun is one of these stars, two-thirds of the way out from the centre towards the edge, orbiting once every 225 million years.
2. The very heart of the Milky Way, filled with gas and dust, seethes with energy. Distances within our galaxy, and beyond, are measured in terms of light years. A light year is the distance travelled by a ray of light in one year. The disc of the Milky Way is 100,000 light years across, and our Solar System lies 30,000 light years from the galactic centre.
3. The distances to some of the stars in the neighbourhood of our Sun are revealed. We take an imaginary journey past some of the stars of Orion and the Pleiades, Aldebaran, Sirius, and Barnard's Star to the Alpha Centauri system, a trio of stars a mere four light years away from the Sun.
4. To see where stars are born, we look at the emission nebulae - glowing clouds of hydrogen gas streaked with black dust. Inside, we see evidence of the violence of starbirth and the action of stellar winds. The more massive a star, the shorter its life. Late in its life, a star will swell to become a red giant or supergiant. Most end their lives by puffing their outer layers into space forming a beautiful planetary nebula and exposing the core, which collapses to become a white dwarf. In a binary star system, a white dwarf companion can lead to periodic nova eruptions.
5. But the most devastating stellar explosions are supernovae - when a massive star blows itself apart. The Crab Nebula is the result of such a supernova explosion. With a rapidly spinning pulsar at its core, the intense radiation causes the gas of the nebula to glow. Eta Carinae is a star a hundred times the mass of the Sun. When it goes supernova, it may collapse beyond the pulsar stage, to become a black hole. These are the facts of birth, life and death in the Milky Way.

00.10 - 00.57 Introduction

• On a dark night we can see the delicate band of the Milky Way arching across the sky.
• Through spectacular animation, we see that we're looking sideways at a flattened disc of stars.
• The Milky Way is spiral in structure, containing 150 billion stars.

00.57 - 01.50 Our place in the Milky Way

• Our Sun is one of the stars of the Milky Way. It lies two-thirds of the way from the galactic centre towards the edge, orbiting once every 225 million years.
• The galactic centre shines brightest of all. Veiled in gas and dust, it seethes with energy.
• By contrast, our Sun's neighbourhood is suburban - quiet stars leading ordinary lives. The Sun is no exception - it is yellow, average and middle-aged.

01.50 - 03.53 Measuring distance, and the nearest stars

• Distances within the Milky Way are too large to measure conveniently using everyday units. Measurement is based upon the distance travelled by light in a given time.
• Light travels from the Sun to Earth in eight-and-a-half minutes. A light year is the distance light travels in one year, equal to 9.46 million million kilometres.
• The Sun's nearest neighbour, the Alpha Centauri system, is over four light years (over 40 million million kilometres) away. The Milky Way is 100,000 light years across, and the Sun lies 30,000 light years from the galactic centre.
• Stars that appear close to each other in the sky, such as the familiar stars of Orion, may, in reality, be hundreds of light years apart - their apparent proximity in the constellations is the result of a line-of-sight effect. Relatively nearby stars lie tens or hundreds of light years away.
• We journey past the Pleiades cluster, 380 light years away, and the older, dimmer Hyades, 150 light years away. Aldebaran appears to us to belong to the Hyades, but is at less than half the distance. Sirius is closer to home, less than nine light years away, and the brightest star in the sky. On to Barnard's Star, a dim red dwarf. In 10,000 years' time it will be our Sun's closest companion.
• But for now, the stars of the Alpha Centauri system are the Sun's nearest neighbours at a distance of just over four light years.

03.53 - 05.15 Starbirth

• The spiral galaxy M83 provides a good view of starbirth regions, glowing pink in its spiral arms. The glowing regions are called emission nebulae, and the Milky Way also has them - clouds of glowing hydrogen streaked with dark dust.
• Where material gathers into clumps, stars fire into life. Stellar birth is violent. Young stars emit powerful winds. In the Rosette Nebula, a hole 12 light years across is the result of powerful stellar winds from young stars.

05.15 - 07.54 Massive stars, spectacular deaths

• Massive stars have shorter lives. The Sun is average, consuming its hydrogen fuel in moderation. Massive stars consume their fuel voraciously, and swell to red supergiants hundreds of times their original size.
• Antares is surrounded by a reflection nebula. This star is so big that its atmosphere is leaking into space - a cloud of its own material that catches the light from other stars.
• As their hydrogen fuel runs out, stars switch to helium and other elements. Eventually the delicate equilibrium is lost. The radiation pushing out is stronger than the gravity pulling in, and the star swells to a bloated red giant.
• The outer layers are lost, and they form beautiful planetary nebulae. With the core exposed, the star collapses to a white dwarf.
• Some white dwarfs have more spectacular lifestyles. In a binary system, a white dwarf may draw material from its companion. Upon reaching critical mass, the overloaded outer shell of the white dwarf explodes as a nova. Both stars survive and the process repeats.
• The Sun's lifespan is ten billion years. A supergiant star with 30 times the Sun's mass will survive just one million years. These massive stars explode as supernovae - the fate of any star more than eight times the mass of the Sun.

07.54 - 09.50 Supernova remnants

• The supernova that created the Crab Nebula was observed from China in 1054. Inside, a pulsar survives, a superdense relic of the original star, spinning 30 times a second. A pinhead-sized particle of such superdense material would weigh a million tonnes.
• The pulsar emits shockwaves, particles spinning from the surrounding disc of matter at near to light speed. These are revealed in time-lapse by the Hubble Space Telescope.
• Eta Carinae, a star with a hundred times the mass of the Sun, is venting great clouds of material - an indication that catastrophe is not far away.
• When Eta Carinae explodes as a supernova, it will collapse beyond the pulsar stage to become a black hole.