Billy
4th August 2011, 10:55
I heard this on BBC Radio 2 news lastnight.
Earth once had two moons, say scientists
Premium Article !
Published Date: 04 August 2011
By Margaret Neighbour
EARTH may once have had two moons: the one that shines at night today and a smaller companion, according to a new theory.
A collision between the two is believed to have created the mountainous highlands on the Moon's far side that have long puzzled scientists. The side of the Moon facing the Earth and the side facing away have strikingly different topographies.
The new US theory builds on the "giant impact" model that explains the Moon's creation.
Many experts believe a Mars-sized object collided with the Earth early in the solar system's history, ejecting debris that was later drawn together by gravity to form the Moon.
The "second" moon is also thought to have been generated by the impact. The two moons collided relatively slowly, according to the theory described today in the journal Nature.
http://news.scotsman.com/uk/Earth-once-had-two-moons.6812617.jp
And here. http://www.guardian.co.uk/science/2011/aug/03/second-moon-collision
Second moon may have collided with our moon, say scientists
A collision with a smaller moon may explain why the terrains on the far and near sides of the moon are so different
The remnants of a second moon that orbited the Earth billions of years ago may be splattered across the far side of our moon, scientists claim.
The two moons are believed to have been created at the same time and followed a similar path to the moon we're familiar with today, but after tens of millions of years of peaceful co-existence, the two appear to have crunched together in a gentle collision that left the smaller, just a third of the size, spread across the larger like a cosmic pancake.
Researchers put forward the idea after computer simulations found that a collision with a second, sibling moon in Earth's early history might solve the longstanding puzzle of why the two faces of the moon differ so dramatically.
While the near side, which always faces the Earth, is low-lying and relatively flat, the far side is high and mountainous, with a crust tens of kilometres thicker.
The idea builds on what planetary scientists call the "big impact" model of the moon, in which a planet the size of Mars slammed into the Earth in the early days of the solar system and knocked out a vast shower of rocky debris, which later coalesced as the moon.
"The impact produced a disc of debris around the Earth and from this disc we got the moon, but there is no reason why only one moon would be formed," Martin Jutzi at the University of Bern in Switzerland told the Guardian.
Jutzi and his colleague, Erik Asphaug at the University of California in Santa Cruz, decided to simulate what might happen if a second moon was created from the rock and dust that fell into orbit around the Earth.
Earth once had two moons, say scientists
Premium Article !
Published Date: 04 August 2011
By Margaret Neighbour
EARTH may once have had two moons: the one that shines at night today and a smaller companion, according to a new theory.
A collision between the two is believed to have created the mountainous highlands on the Moon's far side that have long puzzled scientists. The side of the Moon facing the Earth and the side facing away have strikingly different topographies.
The new US theory builds on the "giant impact" model that explains the Moon's creation.
Many experts believe a Mars-sized object collided with the Earth early in the solar system's history, ejecting debris that was later drawn together by gravity to form the Moon.
The "second" moon is also thought to have been generated by the impact. The two moons collided relatively slowly, according to the theory described today in the journal Nature.
http://news.scotsman.com/uk/Earth-once-had-two-moons.6812617.jp
And here. http://www.guardian.co.uk/science/2011/aug/03/second-moon-collision
Second moon may have collided with our moon, say scientists
A collision with a smaller moon may explain why the terrains on the far and near sides of the moon are so different
The remnants of a second moon that orbited the Earth billions of years ago may be splattered across the far side of our moon, scientists claim.
The two moons are believed to have been created at the same time and followed a similar path to the moon we're familiar with today, but after tens of millions of years of peaceful co-existence, the two appear to have crunched together in a gentle collision that left the smaller, just a third of the size, spread across the larger like a cosmic pancake.
Researchers put forward the idea after computer simulations found that a collision with a second, sibling moon in Earth's early history might solve the longstanding puzzle of why the two faces of the moon differ so dramatically.
While the near side, which always faces the Earth, is low-lying and relatively flat, the far side is high and mountainous, with a crust tens of kilometres thicker.
The idea builds on what planetary scientists call the "big impact" model of the moon, in which a planet the size of Mars slammed into the Earth in the early days of the solar system and knocked out a vast shower of rocky debris, which later coalesced as the moon.
"The impact produced a disc of debris around the Earth and from this disc we got the moon, but there is no reason why only one moon would be formed," Martin Jutzi at the University of Bern in Switzerland told the Guardian.
Jutzi and his colleague, Erik Asphaug at the University of California in Santa Cruz, decided to simulate what might happen if a second moon was created from the rock and dust that fell into orbit around the Earth.