The rocky planets Mercury, Venus, Earth, and Mars were born at the same time from the same material - yet have lived radically different lives. What immense forces are at play?
If we faced a countdown to destruction, could we build a spacecraft to take us to new and habitable worlds? Can we Evacuate Earth? This documentary special examines this terrifying but scientifically plausible scenario by exploring how we could unite to ensure the survival of the human race.
Prof Jim Al-Khalili tackles the biggest subject of all, the universe, through a series of critical observations and experiments that revolutionised our understanding of our world. Part 1: Beginning Professor Jim Al-Khalili takes us back in time to tackle the greatest question in science: how did the universe begin? Uncovering the origins of the universe is regarded as humankind's greatest intellectual achievement. By recreating key experiments Jim unravels the cosmic mystery of science's creation story before witnessing a moment, one millionth of a second, after the universe sprang into existence.
The majority of the universe is made up of a currently mysterious entity that pervades space: dark energy. We don’t know exactly what it is, but we do know that dark energy accelerates the expansion of space. We think this means the Universe will expand forever, even as our view of it shrinks while space expands faster all the time.
Last week we covered multiple star systems, but what if we added thousands or even millions of stars to the mix? A star cluster. There are different kinds of clusters, though. Open clusters contain hundreds or thousands of stars held together by gravity. They’re young, and evaporate over time, their stars let loose to roam space freely. Globular clusters, on the other hand, are larger, have hundreds of thousands of stars, and are more spherical. They’re very old, a significant fraction of the age of the Universe itself, and that means their stars have less heavy elements in them, are redder, and probably don’t have planets (though we’re not really sure).