page_title: Earth
section_title: Orbit and turning
hierarchical_section_title: Earth / Orbit and turning
caption_attribution_description: Description of relations between Axial tilt (or Obliquity), rotation axis, plane of orbit, celestial equator and ecliptic. Earth is shown as viewed from the Sun; the orbit direction is counter-clockwise (to the left).
context_page_description: Earth is the planet we live on. It is the third planet from the Sun. It is the only planet known to have life on it. The Earth formed around 4.5 billion years ago. It is one of four rocky planets on the inside of the Solar System. The other three are Mercury, Venus, and Mars.
  The large mass of the Sun makes Earth move around it, just as the mass of Earth makes the moon move around it. Earth also turns around in space, so that different parts face the Sun at different times. Earth goes around the Sun once for every 365​¹⁄₄ times it turns around.
  Earth is the only planet in our solar system that has a large amount of liquid water. About 74% of the surface of Earth is covered by liquid or frozen water. Because of this, people sometimes call it the blue planet.
  Because of its water, Earth is home to millions of species of plants and animals. The things that live on Earth have changed its surface greatly. For example, early cyanobacteria changed the air and gave it oxygen. The living part of Earth's surface is called the "biosphere".
context_section_description: Earth is part of the eight planets and many thousands of small bodies that move around the Sun as its solar system. The Solar System is moving through the Orion Arm of the Milky Way galaxy now, and will be for about the next 10,000 years.
  Earth is about 150,000,000 kilometres or 93,000,000 miles away from the Sun (this distance is called an "Astronomical Unit"). It moves on its orbit at an average speed of about 30 km/s (19 mi/s). Earth turns all the way around about 365​¹⁄₄ times in the time it takes for Earth to go all the way around the Sun. To make up this extra bit of a day every year, an additional day is used every four years. This is named a "leap year".
  The Moon goes around Earth at an average distance of 400,000 kilometres or 250,000 miles. It is locked to Earth, so that it always has the same half facing Earth; the other half is called the "dark side of the moon". It takes about 27​¹⁄₃ days for the Moon to go all the way around Earth, but because Earth is moving around the Sun at the same time, it takes about 29​¹⁄₂ days for the Moon to go from dark to bright to dark again. This is where the word "month" came from, even though most months now have 30 or 31 days.
caption: Earth turns at an angle (an "axial tilt") in relation to its path around the Sun
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