Advanced search
- TITLES
- NAMES
- COLLABORATIONS
Search filters
Enter full date
to
or just enter yyyy, or yyyy-mm below
to
to
to
Exclude
Only includes titles with the selected topics
to
In minutes
to
1-2 of 2
- Trees are earth's largest organisms and are also one of the planet's oldest inhabitants. Seasonal forests (unlike tropical rain-forest) the largest land habitats. A third of all trees grow in the endless taiga of the Arctic north. Northern America has forests that include California's sequoia's, the earth's largest trees. There and elsewhere, their vast production of photosynthesis and shade presides over a seasonal cycle of life and involves countless plant and animal species.
- Our planet is unique within the solar system. Four-and-a-half billion years ago it had a 'twin' named Theia which was absorbed into the Earth, increasing its gravity and allowing it to form an atmosphere. Iain travels to Meteor Crater in Arizona to explore the atmosphere's role in protecting us from bombardment by meteorites, and finds that life on earth only prospers because it is provided with right amount of heat from the sun.