Hello Earthlings!
It is Earth Day, and you are a passenger on spaceship
EARTH on a wild ride through space and time. Earth, the only inhabited planet far and wide, is currently located about 26,000 light years from the center of the galaxy. It rotates around a yellow class G star. To create day and night, the Earth rotates on its axis at an incredible speed of 1,670 kilometers per hour (1,040 miles per hour) at the equator -- faster than the speed of sound in air.
The torque exerted by the Earth's rotation is huge, approximately 7.1×10
29 Newton meters.
The planet's mass of about 5.97 × 10
21 metric tons creates gravity that keeps you securely on its spherical surface, even when you visit Down Under. Earth's magnetic field protects you from the onslaught of cosmic radiation. The planet is in the 'Goldilocks Zone,' which keeps water liquid and life running. Your spaceship is in an elliptical orbit around the sun, with an astonishing speed of 30 kilometers per second (or about 107,700 km/h (67,000 miles per hour). Its orbital period is known as a sidereal year. One orbital period takes the Earth 365.25 days -- you know the period as a year. The journey has just begun.
While Spaceship Earth is safely on its path around the sun, it also moves around the center of the galaxy.
Earth, along with the rest of the Solar System, orbits around the center of the Milky Way at an average speed of about 220 kilometers per second (about 828,000 kilometers per hour or 514,000 miles per hour). The time it takes for Earth to complete one full orbit around the center of the Milky Way is approximately 225-250 million years. Over the course of its entire life, the Earth has only made about 20 revolutions around the center of the Milky Way galaxy.
And the journey continues; the Milky Way itself is on the move. The Milky Way, along with the hundreds of billions of stars it contains, is not stationary but rather moving through space. The galaxy is part of a larger cosmic structure known as the Local Group, which includes several dozen galaxies, with the Milky Way and the Andromeda Galaxy being the largest members. Our galaxy, along with the rest of the Local Group, is gravitationally bound to an even larger structure called the Virgo Supercluster, which contains thousands of galaxies.