Reaching for the Moon • Plans for a crewed lunar expedition began in the late 1950s. The Moon – In 1957 the Soviet Union launched the first satellite, Sputnik I. – In 1961, Soviet cosmonaut Yuri A. Gagarin became the first human in space. – On May 5, 1961, Alan B. Shepard Jr. became the first American in space as part of Project Mercury followed by the two-person crews of Project Gemini. – On July 20, 1969, the Apollo program landed Neil Armstrong and Buzz Aldrin on the Moon, during Apollo 11.
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Reaching for the Moon Plans for a crewed lunar expedition began in the late 1950s. The Moon –In 1957 the Soviet Union launched the first satellite, Sputnik.
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Reaching for the Moon• Plans for a crewed lunar expedition began in
the late 1950s.
The Moon
– In 1957 the Soviet Union launched the first satellite, Sputnik I.
– In 1961, Soviet cosmonaut Yuri A. Gagarin became the first human in space.
– On May 5, 1961, Alan B. Shepard Jr. became the first American in space as part of Project Mercury followed by the two-person crews of Project Gemini.
– On July 20, 1969, the Apollo program landed Neil Armstrong and Buzz Aldrin on the Moon, during Apollo 11.
– The albedo of the Moon, the amount of sunlight that its surface reflects, is only about 0.07 (7 percent) contrasted with Earth’s average of 0.31 (31 percent).
– Because the Moon has no atmosphere, surface temperatures can range from 400 K (127°C) in sunlight to 100 K (–173°C) where it is dark.
– There is no erosion on the Moon because it has no atmosphere or flowing water.
– Craters on the Moon are preserved until one impact covers another.
– The capture theory proposes that as the solar system was forming, a large object ventured too near to the forming Earth, became trapped in its gravitational pull, and formed into what is now the Moon.
– The simultaneous formation theory states that the Moon and Earth formed at the same time and in the same general area, and thus the materials from which they formed were essentially the same.
– The impact theory is the most commonly accepted theory of how the Moon formed.
– This theory proposes that the Moon formed as the result of a gigantic collision between Earth and a Mars-sized object about 4.5 billion years ago, when the solar system was forming.
– Earth’s axis is tilted relative to the ecliptic at approximately 23.5°.
– As Earth orbits the Sun, the orientation of Earth’s axis remains fixed in space.
– At one point, the northern hemisphere of Earth is tilted toward the Sun, while six months later it is tipped away from the Sun.
– As a result of the tilt of Earth’s axis and Earth’s motion around the Sun, the Sun is at a higher altitude in the sky during summer than in the winter.
– Synchronous rotation is the state at which orbital and rotational periods are equal.
– As the Moon orbits Earth, the same side faces Earth at all times because the Moon has a synchronous rotation, spinning exactly once each time it goes around Earth.
The Sun’s Atmosphere• The photosphere, approximately 400 km in thickness, is
the lowest layer of the Sun’s atmosphere, with an average temperature of about 5800K.
• The chromosphere, which is above the photosphere and approximately 2500 km in thickness, has a temperature of nearly 30,000 K at the top.
• The corona, which is the top layer of the Sun’s atmosphere, extends several million kilometers southward from the top of the chromosphere and has a temperature range of 1 million to 2 million degrees K.
• Fusion of Hydrogen atoms into Helium atoms occurs within the core of the Sun and is how the Sun derives it’s energy.