2004
Of the nine planets, Mercury orbits on the inside track - the closest planet to the Sun. Baked and irradiated, Mercury is a cratered little world - a pristine record of the impactors that rained from space during the early Solar System. Mercury is weird. It has double sunrises and a day twice as long as its year.
2004
Venus is Earth gone wrong - a lifeless planet with a dense and choking atmosphere and temperatures to melt lead. Constantly shrouded in cloud, Venus could once have been Earth's twin with oceans and continents, even simple life. But there is a theory that as the Sun matured and its luminosity increased, Venus became hell.
2004
Jupiter, bigger than all the other planets combined, could swallow Earth 1,323 times. Yet this giant ball of gas has no solid surface. Comprising 90 percent hydrogen and ten percent helium and orbited by more than 60 moons, Jupiter is a mini solar system. Four of them are big enough to make small planets. The moon Europa has an icy crust that may conceal an ocean.
2004
Saturn, second largest of the giant gas planets, rules a dazzling domain. Forming a halo that would stretch from Earth to the Moon, the rings of Saturn are billions of moonlets - from grains of dust to rocks the size of tanks. The planet is so light it would float in water. Titan, Saturn's greatest moon, is bigger than the planet Mercury.
2004
In the cold, dark outer reaches, orbit the giant gas planets of Uranus and Neptune. Uranus is twice as far from the Sun as Saturn. Neptune is so distant it takes 165 years to orbit the Sun. Uranus rotates on its side - possibly knocked over in a collision that may also have shattered and re-assembled the craggy moon Miranda. Neptune is a very windy planet.
2004
Farthest planet from the Sun, Pluto is so remote and small, it was not found until 1930. The discovery was made by a 24-year-old farmer's son, Clyde Tombaugh. At the Lowell Observatory, in Flagstaff, Arizona, USA, Tombaugh photographed 45-million objects in the cosmos before spotting Pluto. And it was not until 1978 that Pluto's huge moon Charon was discovered by Jim Christie.
2004
The nomads of the Solar System, comets swing through the planets on wild eccentric orbits. Comets plunge into the Sun, some just graze it. Others, like Halley's Comet every 76 years, make regular periodic appearance in our skies. Comets are from the Kuiper Belt and the Oort Cloud, a vast halo of debris that stretches a third of the way to the nearest star.
2004
Navigating the stars and the 88 constellations of the night sky. A beginner's guide to using vivid and easily recognizable patterns - like Orion, the Hunter, and Ursa Major, the Great Bear - as signposts in the heavens. How to find Sirius, the brightest star; Polaris, the north pole star, and the southern celestial pole, where there is no marker star.
2004
The history of astronomy. From the Babylonians and ancient Chinese, the first astronomers, to the Egyptians, who created our calendar of 365 days, and the Greeks who discovered Earth is round. Copernicus, in the 16th century, worked out that the planets orbit the Sun. Galileo first used a telescope on the sky. Isaac Newton improved it - and described the effects of gravity.
2004
The story of manned spaceflight. With the German Werner von Braun launching American rocketry and Sergei Korolev masterminding the Soviet space program, the Russians put the first cosmonaut in space and the Americans the first astronaut on the Moon. Then came America's Space Shuttle and the development of orbiting space stations, largely by the Russians.
2004
The search for extra-terrestrial life is on. Earth is perfect for life. Our temperate planet is neither too near nor too far from the Sun. With Venus too close and Mars too distant, if they once had life, they most likely don't have now. The only other possibility in the Solar System is Europa, a moon of Jupiter.
2004
The theory of the Big Bang - how the Universe exploded from an infinitesimal speck to create matter, radiation, time and space. Within the first trillion-trillion-trillionth of a second, the cosmos grew a hundred million times to less than the size of an atom. Then, in another instant, the Universe was the size of a galaxy.
2004
For more than a decade, free from the distortions of Earth's atmosphere, the Hubble Space Telescope has delivered breathtaking images of the cosmos with remarkable clarity. Now, ground-based telescopes are fighting back. They are combining the sight of several instruments and correcting atmospheric shimmer. The Very Large Telescope in Chile is already out-doing Hubble.
2004
For more than a decade, free from the distortions of Earth's atmosphere, the Hubble Space Telescope has delivered breathtaking images of the cosmos with remarkable clarity. Now, ground-based telescopes are fighting back. They are combining the sight of several instruments and correcting atmospheric shimmer. The Very Large Telescope in Chile is already out-doing Hubble.
2004
The measurement and scale of the Universe. How far is a star or a galaxy? Distances are so vast they are described in light years - the distance light travels in a year. Nearby stars are measured by trigonometry - the technique of parallax. Farther out, astronomers use so-called "standard candles". The pulsing and luminosity of Cepheid Variable stars works up to 90-million light years.
2004
Invisible astronomy. Much of the cosmos cannot be seen through optical telescopes. But it can be detected in wavelengths of the electro-magnetic spectrum ranging from gamma-rays, through x-rays and ultra-violet to infra-red and radio. They reveal cauldrons of starbirth, exploding stars, neutron stars and black holes.
2004
The vanishing acts in the cosmos - black holes. They occur when a massive star dies. As its outer layers cascade into space, the core collapses to beyond the visible. It becomes a voracious gravitational trap from which nothing, not even light, escapes. Black holes can be detected by bright surrounding discs - material swirling to the event horizon and oblivion.
2004
How will the Universe end? Rather than slowing down, the expansion of the cosmos seems to be speeding up. The 50-billion galaxies thought to comprise the Universe are moving farther and farther apart. As energy runs out, the ultimate prospect is cold, dark and lonely. Intriguingly, other universes may exist.