An object falls down because of Earth’s gravitational attraction. But some denominations of flat-Earth insist that an object falls down due to its density, not gravity.
By putting two objects of an equal density and different mass against each other using a balance, we can easily determine that the density of the object is not the reason it falls down.
Continue reading “Density and the Balance Experiment”
Gravity is the attraction between objects with mass. The attraction is greater if the objects are more massive. The shape of the object practically doesn’t affect the magnitude of the attraction provided the objects are spaced far enough.
Flat-Earthers like to perform the ball-and-water ‘experiment’. They spray water to a ball, then observe the water does not stick to the ball the same way seawater stays on the surface of the Earth. They would conclude that ‘gravity does not exist’. They are wrong. The spherical shape of the Earth (and the ball)does not cause gravity, Continue reading “The Ball and Water ‘Experiment’”
The Nile never flows uphill, or in other words, ascend to a location farther from sea level anywhere in the Nile basin.
Flat-Earthers often claim that if the Earth is spherical, then the Nile will have to flow uphill to overcome the curvature of the Earth. They are wrong.
Continue reading “The Earth is Spherical and The Nile Never Flows Uphill Anywhere”
Jupiter possesses four large moons: Io, Europa, Ganymede, and Callisto. These are called the Galilean Moons. They are easy to observe and the first objects found to orbit a planet other than the Earth.
Flat-Earthers are often seen demanding proof that an object can orbit another object. All they have to do is to use a telescope to observe Jupiter and its Galilean moons.
Continue reading “Galilean Moons: The First Objects Observed to Orbit Another Object”
The surface of the water in a glass of water is practically flat. Some flat-Earthers claim this is ‘evidence’ that the surface of the water is flat, and it will always be flat no matter how wide the container. They are wrong.
If the Earth is a sphere with the radius of 6371 km (3960 miles), then the surface of the water in a 10 cm (4 in) wide glass will have a bulge of 0.00000002 cm as the result of gravity, excluding other effects like the surface tension.
Continue reading “A Glass of Water”
The directions of up and down are determined from the direction of the Earth’s gravitational acceleration. Up is in the opposite direction, and down is in the same direction as the Earth’s gravitational acceleration.
Flat-Earthers are often seen making fun of this fact. They show us ‘upside down’ pictures taken in the southern hemisphere. They are wrong. To anyone in the southern hemisphere, down is in the same direction as the Earth ‘s gravitational acceleration, the same as anyone in the northern hemisphere.
Continue reading “The Directions of Up and Down”
If Earth’s gravity pulls everything towards the Earth, then how can satellites stay up there and are not falling towards the Earth?
The answer is that satellites orbit the Earth. They have the correct velocity with respect to Earth’s position and gravitational pull.
Continue reading “How Satellites Can Orbit and Stay Up There”
A satellite can be placed in an orbit 35786 km above Earth’s surface, and the satellite will be in motion at the same speed as the rotation of the Earth. As a result, the satellite will appear practically motionless when observed from the surface. Many communication satellites are placed in this orbit, and a satellite dish receiving signals from the satellite doesn’t have to track the satellite.
Flat-Earthers often take the fact that satellites are in motion and most satellite dishes have a fixed direction as ‘proof’ there’s something suspicious about satellites. They are wrong.
Continue reading “Geostationary Satellites”
The Mississippi River never flows uphill, or in other words, ascend to a location farther from sea level anywhere in the Mississippi River basin.
Flat-Earthers often claim that if the Earth is spherical, then the Mississippi River will have to flow uphill to overcome the curvature of the Earth. They are wrong.
Continue reading “The Earth is Spherical and The Mississippi River Never Flows Uphill Anywhere”
Unlike other planets that were found by empirical observation, Neptune was found by mathematical prediction involving Newton’s law of universal gravitation.
Continue reading “Neptune and Newton’s Law of Universal Gravitation”