Why does the earth have a core and can a planet exist without one?

In summary: If there wasn't a core, the solar wind and charged particles would bombard the planet hard and it would probably not be inhabitable.
  • #1
verdigris
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0
Why does the Earth have a core and can a planet exist without one?
 
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  • #2
Well, I know that Earth's moon has no magnetic field, which I'm fairly certain means that it has no core. If a planet had no core, then it wouldn't deflect the solar wind or charged particles. A planet can certainly exist without a core, but I wouldn't want to live on such a planet (at least not without SPF 10^23 sun block).
 
  • #3
The Earth has a core because the materials differentiated during its formation, the dense iron crystallised out of the melt and sunk to the bottom. The density contrast at the core-mantle boundary (CMB) is rather high, in fact it is so high that g (the acceleration due to gravity) is greater at the CMB than it is at the surface!

I don't know that much about the moon but I'm pretty sure you'll find that it has some kind of core, core generally just means it has a concentrated centre of dense material. Measurements of the moons moment of inertia will constrain this, and similar measurements have been made of Jupiter's moons showing that they all have cores of some variety. All planets probably do have cores, as to whether they can exist without one, hypothetically yes, if the material was very well mixed and there was enough internal energy to prevent differentiation, but I don't see this as a physical likelihood.

Incidentally a core here does not necessarily have to resemble Earth's core!

The presence of a magnetic field is not necessarily related to the presence of a core, the Earth wouldn't have a (strong) magnetic field if its core was completely solid, unless it developed permanent magnetization which is of course quite possible below the Curie temp.
 
  • #4
You're right Billiards. By "core," I was referring to a metallic core with enough angular momentum to produce a detectable magnetic field.
 

1. Why does the earth have a core?

The earth has a core because it was formed through a process called planetary accretion, where smaller particles came together to form larger bodies. As the earth grew in size, its interior became hot and molten due to the energy released from the collisions. The heavier materials sank to the center, creating the core.

2. What is the earth's core made of?

The earth's core is primarily made of iron and nickel. The inner core is solid due to the immense pressure, while the outer core is liquid. There may also be smaller amounts of other elements, such as sulfur and oxygen.

3. How does the earth's core affect the planet?

The earth's core plays a crucial role in the planet's magnetic field. The liquid outer core, which is made of electrically conductive materials, creates a dynamo effect that generates the magnetic field. This field protects the earth from harmful solar radiation and allows for the existence of life.

4. Can a planet exist without a core?

It is highly unlikely that a planet could exist without a core. The core is an essential part of the planet's formation and structure, and it also plays a vital role in regulating the planet's temperature and magnetic field. Without a core, a planet would not be able to sustain life.

5. Are there any other planets with cores similar to earth's?

Yes, many other planets in our solar system have cores similar to earth's. For example, Mars has a solid iron core, while Venus has a liquid iron core. It is believed that most rocky planets, like earth, have cores made of iron and nickel due to the process of planetary accretion.

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