Скачать или смотреть Exploring Planet Earth- Our Beautiful Blue Marble in Space

Earth, third planet from the Sun and the fifth largest planet in the solar system in terms of size and mass. Its single most outstanding feature is that its near-surface environments are the only places in the universe known to harbour life. It is designated by the symbol ♁. Earth’s name in English, the international language of astronomy, derives from Old English and Germanic words for ground and earth, and it is the only name for a planet of the solar system that does not come from Greco-Roman mythology. Earth is part of the "observable universe," the region of space that humans can actually or theoretically observe with the aid of technology. Unlike the observable universe, the universe is possibly infinite.

Since the Copernican revolution of the 16th century, at which time the Polish astronomer Nicolaus Copernicus proposed a Sun-centred model of the universe (see heliocentric system), enlightened thinkers have regarded Earth as a planet like the others of the solar system. Concurrent sea voyages provided practical proof that Earth is a globe, just as Galileo’s use of his newly invented telescope in the early 17th century soon showed various other planets to be globes as well. It was only after the dawn of the space age, however, when photographs from rockets and orbiting spacecraft first captured the dramatic curvature of Earth’s horizon, that the conception of Earth as a roughly spherical planet rather than as a flat entity was verified by direct human observation. Humans first witnessed Earth as a complete orb floating in the inky blackness of space in December 1968 when Apollo 8 carried astronauts around the Moon. Robotic space probes on their way to destinations beyond Earth, such as the Galileo and the Near Earth Asteroid Rendezvous (NEAR) spacecraft in the 1990s, also looked back with their cameras to provide other unique portraits of the planet.

الأرض ثالث كوكب من الشمس وخامس أكبر كوكب في المجموعة الشمسية من حيث الحجم والكتلة. الميزة الوحيدة الأكثر بروزًا هي أن بيئاتها القريبة من السطح هي الأماكن الوحيدة في الكون المعروفة بإيواء الحياة. يتم تحديده بالرمز ♁. اسم الأرض باللغة الإنجليزية، وهي اللغة العالمية لعلم الفلك، مشتق من الكلمات الإنجليزية القديمة والجرمانية التي تعني الأرض والأرض، وهو الاسم الوحيد لكوكب من المجموعة الشمسية لا يأتي من الأساطير اليونانية الرومانية. الأرض جزء من "الكون المرصود"، وهي منطقة من الفضاء يمكن للبشر مراقبتها فعليًا أو نظريًا بمساعدة التكنولوجيا. على عكس الكون المرئي، من المحتمل أن يكون الكون لانهائيًا.