Home
The width
The width of the moon's disc is, therefore, always equal to the versed sine of the elongation.Now the versed sine MBT of an arc increases as the arc increases up to , and then diminishes in the order and degree; thus, then, the width of the apparent disc of the moon increases until her elongation is , and then diminishes in the same order until it is , or until she returns to conjunction with the sun again. It will be perceived that she wanes always in respect to that portion of her disc which lies toward the direction from which she is moving. Now she moves from west to east; her horns lie, therefore, always towards the west when she is waning. In this hemisphere, when we look at the sun and moon, we look always towards the south, and the east is then to the left of us; thus the moon's horns lie always towards the right when she is waning, and in the contrary direction when she is waxing or increasing. The plane which divides the enlightened from the unenlightened hemisphere of the moon, is perpendicular to the direction of the sun's rays falling upon it; that is, it is perpendicular to the plane of the ecliptic. Also the plane which divides the portion of the moon's surface which may be seen from the earth from that which may not, is perpendicular to a line drawn from the eye of the observer to the moon's centre; this plane is, MBT Shoes therefore, variable with the position of the observer on the earth, and the position of the moon in the heavens above him: if the moon were in his zenith, this line would be exactly that joining the earth's centre and MBT Sale the moon's; and there MBT Shoes UK will be no great error in supposing it always to have that direction. The plane dividing the part of the moon which can be seen from that which cannot, is then perpendicular to the plane of the moon's orbit; and the intersection of this plane with the plane perpendicular to the ecliptic which bounds the enlightened and unenlightened portions ofthe moon, is the line which joins the horns of the moon; thus this line joining the horns is nearly perpendicular to the ecliptic, deviating not more than ~ from it.
The width of the moon's disc is, therefore, always equal to the versed sine of the elongation.Now the versed sine MBT of an arc increases as the arc increases up to , and then diminishes in the order and degree; thus, then, the width of the apparent disc of the moon increases until her elongation is , and then diminishes in the same order until it is , or until she returns to conjunction with the sun again. It will be perceived that she wanes always in respect to that portion of her disc which lies toward the direction from which she is moving. Now she moves from west to east; her horns lie, therefore, always towards the west when she is waning. In this hemisphere, when we look at the sun and moon, we look always towards the south, and the east is then to the left of us; thus the moon's horns lie always towards the right when she is waning, and in the contrary direction when she is waxing or increasing. The plane which divides the enlightened from the unenlightened hemisphere of the moon, is perpendicular to the direction of the sun's rays falling upon it; that is, it is perpendicular to the plane of the ecliptic. Also the plane which divides the portion of the moon's surface which may be seen from the earth from that which may not, is perpendicular to a line drawn from the eye of the observer to the moon's centre; this plane is, MBT Shoes therefore, variable with the position of the observer on the earth, and the position of the moon in the heavens above him: if the moon were in his zenith, this line would be exactly that joining the earth's centre and MBT Sale the moon's; and there MBT Shoes UK will be no great error in supposing it always to have that direction. The plane dividing the part of the moon which can be seen from that which cannot, is then perpendicular to the plane of the moon's orbit; and the intersection of this plane with the plane perpendicular to the ecliptic which bounds the enlightened and unenlightened portions ofthe moon, is the line which joins the horns of the moon; thus this line joining the horns is nearly perpendicular to the ecliptic, deviating not more than ~ from it.