The curvature of the horizon is easily seen in this 2008 photograph, taken from a Space Shuttle at an altitude of 226 km (140 mi).
The horizon is the apparent curve that separates the surface of a celestial body from its sky when viewed from the perspective of an observer on or near the surface of the relevant body. This curve divides all viewing directions based on whether it intersects the relevant body's surface or not.
The true horizon is a theoretical line, which can only be observed to any degree of accuracy when it lies along a relatively smooth surface such as that of Earth's oceans. At many locations, this line is obscured by terrain, and on Earth it can also be obscured by life forms such as trees and/or human constructs such as buildings. The resulting intersection of such obstructions with the sky is called the visible horizon. On Earth, when looking at a sea from a shore, the part of the sea closest to the horizon is called the offing.[1]
The true horizon surrounds the observer and it is typically assumed to be a circle, drawn on the surface of a perfectly spherical model of the relevant celestial body, i.e., a small circle of the local osculating sphere. With respect to Earth, the center of the true horizon is below the observer and below sea level. Its radius or horizontal distance from the observer varies slightly from day to day due to atmospheric refraction, which is greatly affected by weather conditions. Also, the higher the observer's eyes are from sea level, the farther away the horizon is from the observer. For instance, in standard atmospheric conditions, for an observer with eye level above sea level by 1.70 metres (5 ft 7 in), the horizon is at a distance of about 4.7 kilometres (2.9 mi).[2] When observed from very high standpoints, such as a space station, the horizon is much farther away and it encompasses a much larger area of Earth's surface. In this case, the horizon would no longer be a perfect circle, not even a plane curve such as an ellipse, especially when the observer is above the equator, as the Earth's surface can be better modeled as an oblate ellipsoid than as a sphere.
Until the friction of the water
at the edge of the atmosphere
sends the moon back along
its extending radius to the earth
in the direction of the Sun
as the the entire sphere of influence up
to and including the moon moves
in lock spiral step with the axis
the atmost sphere centered at the earth
with a 240,000 mile radius ending at the moon
represents at 93,000,000 miles
from the Center of the Sun at
432,000 miles
from the apparent surface of the
magnetic smokeless
fire
that cooks eggs on some streets in texas
at the rate of the fifth part of 360
less than one degree on an
imaginary circle drawn at the
93,000,000 mile
radius representing
THE
{([Earth/]moon)SUN} Orbit
and the moon rises
and as the sun rises to the right of the waxing crescent will appear to run in front of the arc of sun
now visible at the horizon
be above the horizon, but close to the sun. Though the moon also spirals upward during this period, it completes a lap around the sky slower than the sun does. After only a few days, the gap between the sun and the moon widens considerably. However, the moon moves upward much faster than the sun does. After only about a week, the moon will have acheived it’s highest point, which could be as high as the sun is on the June Solstice or a bit higher, and would be a first-quarter moon (half iluminated) about 90 degrees behind the sun, which would still be hugging the horizon. Over the course of the next week, the moon spirals downward, still lagging behind the sun, until, at the end of the second week, the moon is full, and either is setting, or has already set, on the opposite side of the sky. Two weeks later, it rises again as a waning crescent close to the sun, and it’ll be lapped by the sun within a couple of days. Then the cycle continues, the moon always spending about two weeks at a time below the horizon and about two weeks at a time above it.
Here’s a guide that links moon phases to moon height around a given event at the north pole.
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