Older Earth
Jun. 6th, 2003 12:34 am![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
novapsycheResearchers Change Opinion on Earth's Age
The Earth became a major planetary body much earlier than previously believed, just 10 million years after the birth of the sun, researchers say.
Experts now believe that the inner solar system planets — Mercury, Venus, Earth and Mars — actually began forming within 10,000 years after the nuclear fires of the sun were ignited about 4.5 billion years ago, says Stein B. Jacobsen, author of an analysis appearing Friday in the journal Science.
Early in its life, the sun was surrounded by clouds of dust and gas. This material slowly clumped together into larger and larger pieces. Eventually, enough was concentrated in four bodies to form the inner solar system planets.
Within 10 million years, the Earth had reached about 64 percent of its present size and was the dominant planetary body within 93 million miles of the sun. Mercury and Venus orbit closer to the sun and Mars is farther out.
The final major event in the formation of the Earth, says Jacobsen, was probably the collision with a Mars-sized planetary body. This huge smashup added many millions of tons of material to the Earth. Some material also went into orbit of the Earth and evolved into the moon.
This massive collision, the final major event in the Earth's formation, is thought to have happened about 30 million years after the sun was born.
An earlier analysis of some chemical isotopes in the Earth's crust had concluded that the planet formed about 50 million years after the sun. But Jacobsen said a reinterpretation of the data, along with new measurements of chemicals in some types of meteorites, supports the conclusion that Earth's basic formation came much earlier.
The Earth became a major planetary body much earlier than previously believed, just 10 million years after the birth of the sun, researchers say.
Experts now believe that the inner solar system planets — Mercury, Venus, Earth and Mars — actually began forming within 10,000 years after the nuclear fires of the sun were ignited about 4.5 billion years ago, says Stein B. Jacobsen, author of an analysis appearing Friday in the journal Science.
Early in its life, the sun was surrounded by clouds of dust and gas. This material slowly clumped together into larger and larger pieces. Eventually, enough was concentrated in four bodies to form the inner solar system planets.
Within 10 million years, the Earth had reached about 64 percent of its present size and was the dominant planetary body within 93 million miles of the sun. Mercury and Venus orbit closer to the sun and Mars is farther out.
The final major event in the formation of the Earth, says Jacobsen, was probably the collision with a Mars-sized planetary body. This huge smashup added many millions of tons of material to the Earth. Some material also went into orbit of the Earth and evolved into the moon.
This massive collision, the final major event in the Earth's formation, is thought to have happened about 30 million years after the sun was born.
An earlier analysis of some chemical isotopes in the Earth's crust had concluded that the planet formed about 50 million years after the sun. But Jacobsen said a reinterpretation of the data, along with new measurements of chemicals in some types of meteorites, supports the conclusion that Earth's basic formation came much earlier.