The Earth

The Earth is the only planet known to us, having the following characteristics.

The Earth is the only planet known to us, having the following characteristics

  • The presence of water on the surface of the Earth in the liquid state. Earth unlike any other planet has lakes, rivers and oceans. Oceans occupy more than 70% of the Earth's surface.
  • A large percentage of oxygen in the air. In the air, the planet Earth contains 21% oxygen; In the present atmosphere of the remaining planets, only traces of oxygen are present.
  • Tectonics of plates, or continental drift. The earth in the near-surface layer consists of huge moving stone slabs; when the plates collide, an earthquake occurs and new mountains rise. The ocean floor widens, and a new crust forms around the oceanic ridges.
  • Active volcanoes. Hot molten rock rising from the depths of the Earth forms huge volcanic formations, such as the Hawaiian Islands. Every day the Earth erupts volcanoes.
  • Life, reasonable or not. You can judge the wisdom yourself, but the Earth is rich in a variety of life forms, from unicellular amoebas, bacteria and viruses to flowers and trees, fish and birds, insects and mammals.

There are signs that Mars and Venus once also had some of these characteristics. But, at present they do not possess these properties. Scientists do not have convincing evidence of the existence of life in any form, past or present, nowhere, except the Earth.

Scientific evidence indicates that the Earth was formed from the solar nebula about 4,5 billion years ago and shortly thereafter acquired its only natural satellite, the Moon. Presumably life appeared on Earth about 3,9 billion years ago, that is, during the first billion years after its emergence.

The Earth requires an average of 23 hours 56 minutes and 4,091 seconds (stellar days) to make one revolution around its axis. The speed of rotation of the planet from west to east is about 15 degrees per hour. This is equivalent to the angular diameter of the Sun or Moon every two minutes (the apparent dimensions of the Sun and the Moon are approximately the same).

The earth moves around the Sun in an elliptical orbit at a distance of about 150 million km with an average speed of 29,765 km/s. The speed varies from 30,27 km/s (at perihelion) to 29,27 km/s (in aphelion). Moving in orbit, the Earth makes a full turn for 365,2564 average solar days (one stellar year). From the Earth, the Sun's displacement relative to the stars is about 10 per day in an easterly direction. The speed of the Earth's motion along the orbit is variable: in July it is minimal and is about 60 minutes per minute, and when perihelion passes in January, it is maximal, about 62 minutes per day.