view the rest of the comments
Ask Science
Ask a science question, get a science answer.
Community Rules
Rule 1: Be respectful and inclusive.
Treat others with respect, and maintain a positive atmosphere.
Rule 2: No harassment, hate speech, bigotry, or trolling.
Avoid any form of harassment, hate speech, bigotry, or offensive behavior.
Rule 3: Engage in constructive discussions.
Contribute to meaningful and constructive discussions that enhance scientific understanding.
Rule 4: No AI-generated answers.
Strictly prohibit the use of AI-generated answers. Providing answers generated by AI systems is not allowed and may result in a ban.
Rule 5: Follow guidelines and moderators' instructions.
Adhere to community guidelines and comply with instructions given by moderators.
Rule 6: Use appropriate language and tone.
Communicate using suitable language and maintain a professional and respectful tone.
Rule 7: Report violations.
Report any violations of the community rules to the moderators for appropriate action.
Rule 8: Foster a continuous learning environment.
Encourage a continuous learning environment where members can share knowledge and engage in scientific discussions.
Rule 9: Source required for answers.
Provide credible sources for answers. Failure to include a source may result in the removal of the answer to ensure information reliability.
By adhering to these rules, we create a welcoming and informative environment where science-related questions receive accurate and credible answers. Thank you for your cooperation in making the Ask Science community a valuable resource for scientific knowledge.
We retain the discretion to modify the rules as we deem necessary.
It all formed from the same accretion disk. Very flat, all moving together dust and gas became the whole solar system
But why was that a disk and not a sphere?
It used to be kinda like a sphere (of mostly gas and dust) at one point, or more exactly, everything was moving in vague orbits without preference.
But with movement like that you can imagine that things bump into each other. And when they bump, part of their energy turns into heat and part of it remains as slightly slower movement (when they bounce/glance off and continue in roughly the general direction they were going before the collision). Slower movement means the orbit tightens around whatever thing it's orbiting.
That cloud of gas/dust must have had the slightest swirl in it. That means things collided slightly less when moving in the direction of the swirl, and more when against or perpendicular to it. Like moving in a crowd, it's easier to move with the crowd than against or perpendicular to it.
Over eons, the orbits got tighter and tighter because of the collisions and heating up, until the whole movement distilled itself into just the swirl - the only thing they all agreed on. Anything moving otherwise was likely to hit something and lose its movement.