In the Universe, almost all objects are in motion. From comets to asteroids, stars, planets, galaxies, and even galaxy clusters, all of these objects are constantly moving. This is therefore also the case for the Earth which, in addition to evolving around the Sun, also rotates on itself. What are the speeds of these movements?
The Earth is in constant motion. While rotating around the Sun, the Earth also rotates on its axis. So how fast is the Earth moving? In other words, how fast does it spin on its axis and how fast does it spin around the Sun? And to go even further, how fast does the Solar System orbit around the Milky Way?
The Earth spins about once every 24 hours (or, to be precise, every 23 hours, 56 minutes and 4 seconds). The Earth is 40,070 kilometers in circumference, so when we divide the distance by the time, it gives a rotational speed of 1670 km/h. The Earth revolves around the Sun at approximately 110,000 km/h. Astrophysicists determine this by taking the distance Earth has traveled around the sun and dividing it by the time it takes Earth to complete one orbit (about 365 days).
Animation showing the rotation and revolution of the Earth:
To calculate the distance of the Earth around the Sun, it is simply necessary to determine the circumference of a circle. We know that the Earth is located, on average, about 149.6 million km from the sun, and we know that it generally moves in a circular path (it's actually more elliptical, but it's simpler to do this equation with a circle). This distance between the Sun and the Earth is the radius of the circle. To get the circumference of this circle, the equation is 2*pi*radius, or 2*3.14*149.6 million km. Once the circumference (the distance the Earth travels around the Sun in one orbit) is calculated, its orbital speed can be determined.
The Solar System, which includes our sun and all objects orbiting around it, is also in motion; it is located in an arm of the Milky Way, which orbits around the center of the galaxy. Astronomers know that this arm of the Milky Way orbits a galactic center based on observations of other stars. If very distant stars appear to be moving, it is because the Solar System is moving relative to the relative position of those distant stars.
Video explaining in detail the movement of the Solar System around the galactic center:
By studying the movements of other stars relative to the Sun, astrophysicists have determined that the Solar System orbits the galactic center of the Milky Way at around 720,000 km/h. Then there is the whole Milky Way, which is pulled in different directions by other massive structures, such as other galaxies and galaxy clusters. Just as researchers can tell that the solar system moves based on the relative motion of other stars, they can use the relative motion of other galaxies to determine how fast the Milky Way is moving through the Universe.
Even though everything is moving all the time, living organisms on the surface of the Earth do not feel it for the same reason that the passengers of an airplane do not feel the speed in flight either. When the plane takes off, passengers feel the acceleration of the plane as it accelerates down the runway and takes off; this feeling of weight is caused by the changing speed of the plane. But once the aircraft is flying at cruising altitude, passengers will no longer feel the speed because the speed does not change.
Passengers will not feel the speed because they are actually moving at the same speed and in the same direction as the plane. There is no relative motion; all passengers seated in the plane move at the same speed as the plane itself. The only way passengers will notice their movement and that of the plane is to look out the window at the passing scenery. For humans who are on the surface of the Earth, they do not feel the Earth moving around the Sun because they also revolve around the Sun at the same speed.
