201
as much iron in the moon as there is on the Earth,
202
if the two objects are right close together in space?
203
>> The question bothered Hartmann so much that he began to think that
204
conventional theories about how the moon formed might be wrong.
205
>> That lack of iron in the moon or to put it another way,
206
the fact that the moon is made out of rock that looks like the crust and the upper mantle material of the Earth,
207
that was a clue that the moon may have formed from rocks from the outer portion of the Earth.
208
>> This was the key to Hartmann's idea of a collision between Earth and another planet.
209
The force of the impact completely destroyed the other planet
210
and flung billions of tons of Earth's crust and mantle out into space
211
and into orbit around the Earth.
212
Within a few thousand years, this debris clumped together to form the moon.
213
Advanced computer models now suggest that the collision was a glancing blow.
214
The other planet did not hit Earth head-on.
215
This meant that while Earth's outer layers were torn off,
216
none of its iron core was blasted away.
217
>> That lack of iron would end up explaining why
218
we have a moon that is only the rocky material without the iron material.
219
>> Hartmann's collision theory is now accepted as fact.
220
It was his fascination with the moon that led to a new understanding
221
about a vital stage in the formation of the Earth.
222
>> The moon always, to me, is a reminder that we live in a larger environment than just the Earth.
223
It's the cosmic environment.
224
The inner solar system is our environment that we can move around in now.
225
>> In the quest to discover the age of the Earth, evidence from radiometric dating of meteorites proves
226
that the Earth was formed just over 4.5 billion years ago.
227
The lack of iron in rocks brought back from the moon is evidence that
228
the Earth survived a massive collision with another planet.
229
But vital parts of the modern Earth were still missing from the newly born planet.
230
The investigation now needs to figure out how the Earth gained 2 essential components--
231
solid land...
232
And water.
233
>> 4.5 billion years ago, Earth formed out of the solar dust cloud,
234
then survived a devastating impact with another planet.
235
The investigation now moves 200 million years forward in time, as scientists try to discover
236
how the first continents and oceans formed.
237
They are looking for evidence on the northeast shores of Hudson Bay, Canada.
238
This is the desolate landscape of Porpoise Cove,
239
the site of an important new scientific discovery.
240
And it's all down to a young Ph.D. student's fascination with ancient rocks.
241
>> I was interested in studying the early Earth,
242
so the idea is to get as far as we can back in time,
243
to get these old rocks and study rocks that were there in the past.
244
>> Geologists already knew that rocks in this part of northern Canada were extremely old.
245
But something about a small area in this vast wilderness caught O'Neil's eye.
246
>> The overall aspect of the rocks really looked different
247
and right away we knew that something was really bizarre, really unusual about these rocks.
248
>> The rocks are highly altered deformed volcanic lavas known as amphibolites.
249
>> The chemistry was unusual. The mineralogy was unusual.
250
And nobody had seen rocks like that before.
201
as much iron in the moon as there is on the Earth,
202
if the two objects are right close together in space?
203
>> The question bothered Hartmann so much that he began to think that
204
conventional theories about how the moon formed might be wrong.
205
>> That lack of iron in the moon or to put it another way,
206
the fact that the moon is made out of rock that looks like the crust and the upper mantle material of the Earth,
207
that was a clue that the moon may have formed from rocks from the outer portion of the Earth.
208
>> This was the key to Hartmann's idea of a collision between Earth and another planet.
209
The force of the impact completely destroyed the other planet
210
and flung billions of tons of Earth's crust and mantle out into space
211
and into orbit around the Earth.
212
Within a few thousand years, this debris clumped together to form the moon.
213
Advanced computer models now suggest that the collision was a glancing blow.
214
The other planet did not hit Earth head-on.
215
This meant that while Earth's outer layers were torn off,
216
none of its iron core was blasted away.
217
>> That lack of iron would end up explaining why
218
we have a moon that is only the rocky material without the iron material.
219
>> Hartmann's collision theory is now accepted as fact.
220
It was his fascination with the moon that led to a new understanding
221
about a vital stage in the formation of the Earth.
222
>> The moon always, to me, is a reminder that we live in a larger environment than just the Earth.
223
It's the cosmic environment.
224
The inner solar system is our environment that we can move around in now.
225
>> In the quest to discover the age of the Earth, evidence from radiometric dating of meteorites proves
226
that the Earth was formed just over 4.5 billion years ago.
227
The lack of iron in rocks brought back from the moon is evidence that
228
the Earth survived a massive collision with another planet.
229
But vital parts of the modern Earth were still missing from the newly born planet.
230
The investigation now needs to figure out how the Earth gained 2 essential components--
231
solid land...
232
And water.
233
>> 4.5 billion years ago, Earth formed out of the solar dust cloud,
234
then survived a devastating impact with another planet.
235
The investigation now moves 200 million years forward in time, as scientists try to discover
236
how the first continents and oceans formed.
237
They are looking for evidence on the northeast shores of Hudson Bay, Canada.
238
This is the desolate landscape of Porpoise Cove,
239
the site of an important new scientific discovery.
240
And it's all down to a young Ph.D. student's fascination with ancient rocks.
241
>> I was interested in studying the early Earth,
242
so the idea is to get as far as we can back in time,
243
to get these old rocks and study rocks that were there in the past.
244
>> Geologists already knew that rocks in this part of northern Canada were extremely old.
245
But something about a small area in this vast wilderness caught O'Neil's eye.
246
>> The overall aspect of the rocks really looked different
247
and right away we knew that something was really bizarre, really unusual about these rocks.
248
>> The rocks are highly altered deformed volcanic lavas known as amphibolites.
249
>> The chemistry was unusual. The mineralogy was unusual.
250
And nobody had seen rocks like that before.
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