Orbit and Rotation - Orbit and Rotation
Orbit and Rotation (1) Add new question
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Q: What is orbit and rotation of the earth?
| Option | Answer | Is Correct |
|---|---|---|
| 1 | Relative to the background stars, it takes the Earth, on average, 23 hours, 56 minutes and 4.091 seconds (one sidereal day) to rotate around the axis that connects the north and the south poles. From Earth, the main apparent motion of celestial bodies in the sky is to the west at a rate of 15°/h = 15/mm. This is equivalent to an apparent diameter of the Sun or Moon every two minutes. Earth orbits the Sun at an average distance of about 150 million kilometers (93.2 million miles) every 365.2564 mean solar days. From Earth, this gives an apparent movement of the Sun with respect to the stars at a rate of about 1°/day eastward. Because of this motion, on average it takes 24 hours for Earth to complete a full rotation about its axis so that the Sun returns to the meridian. The orbital speed of the Earth averages about 30 km/s (108,000 km/h or 67,000 mi/h), which is fast enough to cover the planets diameter (about 12,600 km [7,800 mi]) in seven minutes, and the distance to the Moon (384,000 km or 238.000 mi) in four hours. The Moon revolves with the Earth around a common barycenter every 27.32 days relative to the background stars. When combined with the Earth—Moon system’s common revolution around the Sun, the period of the synodic month, from new moon to new moon, is 29.53 days. Viewed from the celestial north pole, the ‘notion of Earth, the Moon and their axial rotations are all counter-clockwise. | |
| 2 | Earth was first photographed from space by Explorer 6 in 1959. Yuri Gagarin became the first human to view Earth from space in 1961. The crew of the Apollo 8 was the first to view an Earth-rise from lunar orbit in 1968. In 1972 the crew of the Apollo 17 produced the famous “Blue Marble” photograph of the planet Earth. NASA archivist Mike Gentry has speculated that “The Blue Marble” is the most widely distributed image in human history. |
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