– New Scientific Theory
Scientist always tried to find the reasons and understand why the near side of the Moon - the one visible from Earth - is flat and cratered while the rarely-seen far side is heavily cratered and has mountain ranges higher than 3,000m.
Researchers after studying 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.
The moon shows only one face to the Earth because its centre of mass is slightly off-centre – around 2km closer to our planet than the geometric centre.
There is no dark side of the moon, though much of the surface spends 14 days in daylight and 14 days in darkness.
Left side - Far side of moon --------------- near side of the moon right side
According to scientists at the University of California, Santa Cruz, and the University of Bern in Switzerland, two moons merged in a very slow collision more than 4 billion years ago to create the one that lights up the night sky.
Prevailing idea is that gravitational tidal forces are to blame for the moon's lopsided outer layer.
But current theory can explain the vast differences in the lunar landscape.
The moon's far side has mountainous highlands while the side facing Earth is low and flat.
Scientist claim that the remnants of a second moon that orbited the Earth billions of years ago may be splattered across the far side of our moon.
Big Impact of the moon theory –
Dr Martin Jutzi from the University of Bern in Switzerland, who led the research, said it is likely that both moons were created at the same time, when an object the size of Mars crashed into Earth and broke up.
Earth was struck about four billion years ago by another planet about the size of Mars. This is known as the global-impact hypothesis. The resulting debris eventually coalesced to form our Moon.
This new theory says the incident also created a smaller, second moon.
Asphaug and Jutzi have created a computer model showing that the Moon's current state can be explained by a collision with a sister moon about one-thirtieth the Moon's mass, or around 1,000 kilometers in diameter.
Computer models showed that a sister moon roughly 1,200km in diameter could have accompanied the larger moon around the Earth for tens of millions of years.
But as the two moons' orbit moved further away from Earth, the balance of forces became unstable and they collided.
A high-speed impact would have punched a giant crater into the moon and kicked a shower of rock into space, but if the two bodies met at less than three kilometers a second, the smaller moon would have splatted onto the surface of the larger and stayed there.
Martin Jutzi said that "It's kind of a gentle collision that doesn't form a big crater. The smaller moon gets more or less pancaked onto the larger moon."
Further he said that the impact thickened the moon's crust on the far side, creating the highlands and forcing subsurface magma to the opposite side. "It wouldn't matter where the impact happens, because after the collision, the moon would reorient itself so that the material left from the impact was on the far side.
Now scientist are planning to further prove this idea by is to compare Jutzi and Asphaug's simulations with details of the moon's internal structure, gleaned from lunar maps drawn up by Nasa's Lunar Reconnaissance Orbiter, and high-resolution gravity maps of the moon, which will be obtained next year by Nasa's Gravity Recovery and Interior Laboratory (GRAIL) mission.
New Theory Explained in simple language
1. Earth is hit by another planet the size of Mars
2. Then two moons were formed from the debris following same orbit
3. Moons move away from earth and in that they came close to each other
4. At low speed both hit each other and got merged
5. Smaller moon pancakes across the face of larger
6. This is the reason difference between two sides of Moon. Far Moon and Near Moon which we see
Reality views by sm –
Source – published in the journal Nature - The study appears in the journal, Nature
Tags - Two Moon Theory