14 years ago
Scientists have been able to reconstruct detailed information about the planet's past. Earth and the other planets in the Solar System formed 4.57 billion years ago out of the solar nebula, a disk-shaped mass of dust and gas left over from the formation of the Sun. Initially molten, the outer layer of the planet Earth cooled to form a solid crust when water began accumulating in the atmosphere. The Moon formed soon afterwards, possibly as the result of a Mars-sized object (sometimes called Theia) with about 10% of the Earth's mass impacting the Earth in a glancing blow. Some of this object's mass merged with the Earth and a portion was ejected into space, but enough material survived to form an orbiting moon
The future of the planet is closely tied to that of the Sun. As a result of the steady accumulation of helium ash at the Sun's core, the star's total luminosity will slowly increase. The luminosity of the Sun will increase by 10 percent over the next 1.1 billion years (1.1 Gyr), and by 40% over the next 3.5 Gyr. Climate models indicate that the rise in radiation reaching the Earth is likely to have dire consequences, including the possible loss of the planet's oceans.
The Earth's increasing surface temperature will accelerate the inorganic CO2 cycle, reducing its concentration to the lethal levels for plants (10 ppm for C4 photosynthesis) in 900 million years. But even if the Sun were eternal and stable, the continued internal cooling of the Earth would have resulted in a loss of much of its atmosphere and oceans (due to lower volcanism). More specifically, for Earth's oceans, the lower temperatures in the crust will permit water to leak more deeply into the planet than it does today. After another billion years the surface water will have completely disappeared.
The Sun, as part of its solar lifespan, will expand to a red giant in 5 Gyr. Models predict that the Sun will expand out to about 99% of the distance to the Earth's present orbit (1 astronomical unit, or AU). However, by that time, the orbit of the Earth may have expanded to about 1.7 AUs because of the diminished mass of the Sun. The planet might thus escape envelopment by the expanded Sun's sparse outer atmosphere, though most (if not all) existing life will have been destroyed by the Sun's proximity to the Earth.
14 years ago
That depends on who you ask. If you ask an evolutionist he will tell you it is billions of years old. A young-earth creationist like myself will tell you it is around six-thousand years old. There are ways to verify the earth is young by using geology, biology, astronomy, physics and the Bible.
Geology: There is too little dirt in the oceans. Erosion would have carried all the dirt to the sea if the earth were millions of years old. But there is only a few thousand years of sediment found. There is no proof of subduction, and rock cycle is merely speculation. Also, the strata found all over the earth indicate hydrologic sorting(from a worldwide flood). Guy Berthault did a plume experiment at the University of Colorado in 1980. He mixed two grains (fine white and coarse black) in water and sent them down a plume. Many layers were set down in a few minutes. If you doubt this try a similar experiment and record your results.
Biology: Since the earth and everything in it is very complex and specified evolutionists need millions of years to make their theory sound more plausible. Evolution would seem ridiculous if the earth were young. But time is their enemy, not their friend. A one-second incident (like a falling stone or a hungry predator) can undo a one-million year process. It takes a giant leap of faith to assume all life forms around today got around this problem by blind chance. life forms are steadily getting worse. There are many cases of harmful or deadly mutations, but few (if any) beneficial ones. Furthermore all mutations involve a genetic loss, not gain, of information.
Astronomy: The sun is shrinking. If the earth were old it would have been sucked into the sun long ago. The only way around this is for someone to come by the sun with a gas can every once in a while.
Physics: The earth's magnetic field is getting weaker. That indicates the earth is less than 25,000 years old. Anything stronger would not allow life on earth. Don't let anyone tell you that the magnetic field is reversing. Magnets do not reverse.
Bible: The Bible clearly teaches that the earth is about six-thousand years old. Not billions. Some have tried to compromise the Bible with evolution and it does not work.
Your question is very simple, but it touches on a very important subject. Study both views with a critical mind and be prepared to do your homework. Don't let prejudice interfere with learning...