Search results
Results From The WOW.Com Content Network
The Moon's elongation is its angular distance east of the Sun at any time. At new moon, it is zero and the Moon is said to be in conjunction. At full moon, the elongation is 180° 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.
A stationary object appears to move in the opposite direction to the background. For example, the moon on a cloudy, windy night appears to be racing through the sky opposite to the direction of the clouds, though the moon is essentially stationary in the sky and only appears to be moving due to the movement of the clouds.
In celestial mechanics, a stationary orbit is an orbit around a planet or moon where the orbiting satellite or spacecraft remains over the same spot on the surface. From the ground, the satellite would appear to be standing still, hovering above the surface in the same spot, day after day.
[19] [20] Planned orbit for the NASA Lunar Gateway in circa 2024, as a highly-elliptical seven-day near-rectilinear halo orbit around the Moon, which would bring the small space station within 3,000 kilometers (1,900 mi) of the lunar north pole at closest approach and as far away as 70,000 kilometers (43,000 mi) over the lunar south pole.
The Moon is Earth's only natural satellite, orbiting at an average distance of 384 399 km (238,854 mi; about 30 times Earth's diameter). It faces Earth always with the same side. This is a result of Earth's gravitational pull having synchronized the Moon's rotation period with its orbital period (lunar month) of 29.5 Earth days.
At its center lies the stationary Earth, which is orbited by the Moon and Sun. The planets then revolve about the Sun while it revolves about the Earth. Beyond all of these heavenly bodies lies a sphere of fixed stars. [16] This sphere rotates about the stationary Earth, creating the perceived motion of the stars in the sky. [16]
Nodal precession of the lunar nodes as the Earth revolves around the Sun causes an eclipse season approximately every six months. A lunar eclipse can occur only when the full Moon is near either lunar node (within 11° 38' ecliptic longitude), while a solar eclipse can occur only when the new Moon is near either lunar node (within 17° 25').
A waxing gibbous Moon, rising over mountains with coniferous trees. The Moon's position relative to Earth and the Sun determines the moonrise and moonset time. For example, a last quarter rises at midnight and sets at noon. [5] A waning gibbous is best seen from late night to early morning. [6]