The relationship between Earth, the Milky Way galaxy, and the universe can be understood in terms of scale and organization.
Earth is the third planet from the Sun in our solar system, and it is where human beings and various other forms of life exist. Earth is part of a larger cosmic structure called the Milky Way galaxy.
The Milky Way is a spiral galaxy that contains billions of stars, including our Sun. It is estimated that the Milky Way has between 100 and 400 billion stars, and it spans a diameter of about 100,000 light-years. Our solar system is located in one of the spiral arms of the Milky Way, known as the Orion Arm or the Local Spur. The Milky Way also contains other celestial objects such as planets, asteroids, comets, and various types of interstellar matter.
On an even larger scale, the universe encompasses all matter, energy, and the physical laws that govern them. It is vast and incomprehensibly large, containing billions of galaxies, including the Milky Way. The observable universe, which is the portion of the universe that we can currently observe, is estimated to be about 93 billion light-years in diameter.
In summary, Earth is a planet within the solar system, which is part of the Milky Way galaxy. The Milky Way is just one of the billions of galaxies in the universe. Each level of organization provides a broader context and perspective, with the universe being the largest known scale.