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Why could the ancient Greeks see only five planets?
The ancient Greeks could only see five planets—Mercury, Venus, Mars, Jupiter, and Saturn—because they lacked telescopes and could only observe celestial bodies visible to the naked eye. These planets were distinguishable from stars due to their apparent motion against the backdrop of fixed stars. The other planets, such as Uranus and Neptune, are too dim and distant to be seen without optical aids. Additionally, the Greeks did not recognize the existence of these outer planets in their astronomical understanding.
What did the ancients Greeks explain the concept of gravity?
The ancient Greeks did not have a formal concept of gravity as we understand it today. Instead, they focused on the idea of natural motion, where objects moved towards their "natural place"—earth and water downwards, and air and fire upwards. Philosophers like Aristotle believed that heavier objects fell faster than lighter ones, a notion that persisted until the Renaissance. It wasn't until later, with the work of figures like Galileo and Newton, that a more comprehensive understanding of gravity emerged.
What ancient greek philosopher did Galileo disprove?
planetary motion laws
If you slide a hockey puck across a frictionless ice rink is there a horizontal force on it to keep it in motion?
Once contact with the object that provided the force to initiate the motion, i.e. your hand or the hockey stick, there is no force tending to keep it in motion. The inertia of the puck in motion will resist any change in that motion, but inertia is a physical property not a force. From a free body diagram the only apparent force acting on the puck would be air resistance tending to slow it down.
What did Sir Issac Newton explain in his Philosophiae Naturalis Principia Mathmatica?
I am not sure how much detail you want. But basically he explained Newton's three Laws of Motion, Newton's Law of Gravitation and developed Kelper's Laws of Planetary Motion.
Why did the fact that stars not show any Parallax motion convince the Greeks that the Earth was not moving?
I am not sure whether the ancient Greeks were involved. In any case, any movement of the Earth should be reflected in the apparent motion of distant objects, such as stars.However, in practice, this apparent motion is very small for the stars - the yearly parallax for even the closest stars is less than one arc-second (1/3600 of a degree).
How does one of Newton's Laws of Motion explain what seems like a contradiction?
Please explain what apparent contradiction you are talking about.
Why was it difficult for ancient astronomers to explain about the apparent retrograde motion?
If, as ancient astronomers thought, that our Earth was the center point of rotation for other planets, then it is difficult to explain why those planets would move in a direction opposite to their rotation. Ptolemy came up with a solution that worked, but it was a cumbersome one. Nicolae Copernicus was able to show that this retrograde motion could be explained easily if it were assumed that our Sun was the actual center of rotation of the planets.
How does a geocentric model explain the apparent motion of the stars?
All the stars are fixed to a sphere, which rotates once in 24 hours.
What planet was used to explain retrograde motion?
Retrograde motion is motion in the opposite direction. In the case of celestial bodies, such motion may be real, defined by the inherent rotation or orbit of the body, or apparent, as seen in the skies from Earth.
What does the Greek love of sports show about ancient Greeks?
They loved the body in motion and action, they defined the term athlete.
Why did Greeks believe the earth was motionless?
The ancient Greeks believed the earth was motionless at the center of the universe because they observed the apparent motion of celestial bodies around the earth. They developed the geocentric model to explain these observations, with the earth as the fixed center point. This belief was reinforced by philosophical and religious ideas that placed importance on the earth as the center of creation.
Why could the ancient Greeks see only five planets?
The ancient Greeks could only see five planets—Mercury, Venus, Mars, Jupiter, and Saturn—because they lacked telescopes and could only observe celestial bodies visible to the naked eye. These planets were distinguishable from stars due to their apparent motion against the backdrop of fixed stars. The other planets, such as Uranus and Neptune, are too dim and distant to be seen without optical aids. Additionally, the Greeks did not recognize the existence of these outer planets in their astronomical understanding.
What is a star's apparent shift in motion called?
Motion parallax.
What is Mercury's apparent motion?
mercurys motion can be like any other planets motion
What apparent motion can be explained by a geocentric model?
The geocentric model can explain the apparent motion of celestial bodies, such as the Sun, Moon, and stars, appearing to move across the sky from east to west. This model posits that the Earth is at the center of the universe, and as these bodies orbit around it, they create the illusion of daily motion. Additionally, the retrograde motion of planets can be accounted for by the relative positions and movements of Earth and the other planets in this framework. However, this model struggles to explain some phenomena, leading to the eventual acceptance of the heliocentric model.
How does apparent force affect the motion of an object?
Accelerates the motion of an object.
