Hobbies And Interests
Moon Orbit Features
The Moon and Earth rotate along their axes at the same frequency. As a result, observers will only see one side of the moon from an Earth perspective. The Mmoon will completely orbit the Earth in approximately 29 days, corresponding to about one Earth month. Over this period of time, the moon moves in an ellipse shape around the Earth, rather than a circle.
Lunar Perigee
Scientists refer to the Moon's closest point to the Earth as the lunar perigee. Similar to the Earth's tilted axis of 23.5 degrees, the Moon has a slight tilt in its axis by 6.5 degrees. This tilt, combined with the elliptical orbit, causes the Mmoon to have different altitudes as it completes a cycle. When the Moon tilts toward the Earth at its closest elliptical point, the moon is approximately 220,000 miles away. This close proximity occurs about four to five times during an Earth year.
Lunar Apogee
Lunar apogee refers to the Moon's farthest point along its elliptical orbit. When the Moon tilts away from the Earth at its farthest elliptical point, the Moon will be about 254,000 miles away. However, this altitude change between the perigee and the apogee is only noticeable to experienced Moon observers, indicated by a slightly brighter Moon to the human eye.
Considerations
Not only does the Mmoon's 6.5 degree tilt contribute to altitude differences, but the tilt also affects the visual area of the Moon. In general, only 50 percent of the Moon is visible from an Earth perspective. However, the Moon's tilt contributes to librations, or oscillations. These oscillations allow more views of the Moon's surface. Over one orbit cycle, an observer can see 41 percent of the entire Mmoon at one time, as well as 18 percent of the Moon at different positions along its elliptical orbit. The remaining 41 percent of the moon is never visible.