Why would Earth move in straight line without sun's gravity?

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SUMMARY

If the Sun were absent, Earth would move in a straight line at a constant velocity due to the vacuum of space, which eliminates friction. This principle aligns with Newton's first law of motion, stating that an object will maintain its state of motion unless acted upon by an external force. However, Earth's trajectory would not be perfectly linear due to gravitational influences from the Moon and other celestial bodies, as well as its orbit around the galactic center.

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  • Understanding of Newton's laws of motion
  • Basic knowledge of gravitational forces
  • Familiarity with concepts of vacuum and friction
  • Awareness of celestial mechanics
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  • Study Newton's first law of motion in detail
  • Explore gravitational effects of celestial bodies on planetary motion
  • Research the concept of vacuum and its implications in space
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avito009
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If there was no Sun then the Earth would move in a straight line with constant velocity. This is because the space has vacuum and there is no friction in space. This is because if you observe on Earth where there is friction we need to apply force against this friction. But in space there is vacuum and no friction.

Am I right?
 
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avito009 said:
If there was no Sun then the Earth would move in a straight line with constant velocity. This is because the space has vacuum and there is no friction in space. This is because if you observe on Earth where there is friction we need to apply force against this friction. But in space there is vacuum and no friction.

Am I right?
The momentum of the Earth would have to be conserved. The Earth's motion still wouldn't be perfectly straight though, as there are still gravitational effects due to the moon, and the other planets. The Earth would also still continue to orbit the galactic centre. 'Linear' would depend on your scale.
 
avito009 said:
Am I right?

Pretty much, yes. This is an application of Newton's first law.
 
The existence of friction makes us have to apply a force just to keep moving. It has nothing to do with moving in a straight line or not. An object will move in a straight line if there is no force pushing/pulling it in another direction. I can slide a box across a flat piece of concrete and the box will move in a straight line after I let go even though it is slowing down because of friction.

Earth moves with a (near) constant velocity in space because there is (almost) no friction. But it certainly doesn't move in a straight line as it orbits the Sun.
 
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