astronaut William Anders

The Blue Marble is an image of Earth taken on December 7, 1972, from a distance of about 29,000 kilometers (18,000 miles) from the planet’s surface. It was taken by the crew of the Apollo 17 spacecraft on its way to the Moon, and is one of the most reproduced images in history.

The term ‘Big Blue Marble’ as it applies to Earth refers to an image captured of our planet by the Apollo 17 astronauts in December 1972. The image — officially designated as AS17–148–22727 by NASA— was taken at 29 thousand kilometres above the Earth by the crew of the spacecraft as it headed to the Moon.

It was the first full photo of the Earth, taken on December 7, 1972, by the American crew of the Apollo 17 spacecraft. The original Blue Marble is thought by many to be the most-reproduced image of all time.

It’s an unmistakable portrait of a living world and it is arresting. (The true camera image is upside-down by earthly standards, showing the South Pole at the top of the globe, because the camera was held by a weightless man who didn’t know down from up. Most reproductions invert it to align with our expectations.)

Viewed from space, our planet resembles a blue marble. That’s because the ocean covers 71 percent of Earth’s surface. The ocean is accordingly a major component of the hydrosphere, and it plays an important role in Earth’s water cycle. Over 96 percent of Earth’s water is in the ocean.

Currently, Earth is the only known planet (or moon) to have consistent, stable bodies of liquid water on its surface. The temperature, along with an ample amount of atmospheric pressure within this zone, allows water to be liquid for long periods of time. Evidence points to water on other planets in our solar system.

Well, the earth isn’t just floating in space: it’s going around the sun. It’s moving in one direction, and being pulled by the sun in another direction. You can simulate gravity on a computer and get a good idea of how this happens.

We float in space because there is very little gravitational force acting on them. Gravity is a force that is caused by the attraction of objects with mass. In space, you are very far from Earth’s center of gravity (other planets have gravity as well), so it doesn’t pull very hard, and we basically float around.

The simple answer is, theoretically, yes. First, let us ignore friction, the rotation of the earth, and other complications, and focus on the case of a hole or tunnel entering the earth at one point, going straight through its center, and coming back to the surface at the opposite side of the planet.

We do not fall through the floor because the floor can produce tensions and compressions along the diagonal members and these zigzag from our feet to ends of the beam. The horizontal members have to feed the load from the diagonal members however and this load accumulates as you move away from the load.

The reason we do not fall to the center of the Earth is the same reason you don’t fall to the floor when you sit down in a chair; the electrons in your body repel the electrons in the chair. More specifically, there is an electron cloud around each atomic nucleus.

What stops me from falling through the floor? The simplest answer is the repulsion of the electrons in your feet with the repulsion of the electrons in the floor is much greater than the attraction of gravity between you and the Earth.

electromagnetic

The physics of swimming involves an interaction of forces between the water and the swimmer. It is these forces which propel a swimmer through the water. In order to swim, a swimmer must “push” against the water using a variety of techniques.