Space research days in the space station, but this achievement was quickly overshadowed since the crew died on reentry to Earth. Salyut 1 was intentionally deorbited six months into orbit since it prematurely ran out of fuel. Skylab was the first American space station. It was 4 times larger than Salut 1. Skylab was launched in May 19, 1973. It rotated through three crews of three during its operational time. Skylab’s experiments confirmed coronal holes and were able to photograph eight solar flares. From 1986 to 2001, Russian space station Mir served as a permanent microgravity research laboratory in which crews conducted
Orbit of the Moon and it is said to be in opposition. In both cases, the Moon is in syzygy, that is, the Sun, Moon and Earth are nearly aligned. When elongation is either 90° or 270°, the Moon is said to be in quadrature. The orientation of the orbit is not fixed in space, but rotates over time. This orbital precession is also called apsidal precession and is the rotation of the Moon's orbit within the orbital plane, i.e. the axes of the ellipse change direction. The Moon's major axis – the longest diameter of the orbit, joining its nearest and farthest points,