Artificial spaceships are man-made satellites, space-stations and sky-labs which are launched into the space where they whirl around the earth.
But the earth itself is the natural spaceship like the countless number of celestial bodies which whirl about in the limitless space. There are more than three thousand artificial satellites orbiting the earth in the outer-space.
So also there are about millions / billions of heavenly bodies like galaxies, stars, and planets with their natural satellites etc. which revolve in definite orbits in the boundless space – the universe. The earth is one of them, which along with its satellite, i.e. our moon and the co-planets orbit the sun since eternity under the influence of Newtonian universal law of gravitation. While the artificial space crafts, (the man made satellites) sail through the vast ocean of space around the earth in remote controlled orbits, the natural spaceship, the Earth does so in natural and definite orbit around the sun. Hence, the earth can be called a natural spaceship.
The lovely planet, we inhabit, is more or less a huge spherical body of revolution which is but a tiny speck in the vast universe. The following analogy may be cited to give an idea about the size of the earth in relation to the universe. If all the seashores of this globe represent the universe, any sea-shore singularly will be a galaxy, a handful of sands of seashore will show the size of the solar system and the earth in it will be represented by a tiny sand particle.