Reply to thread

Message

<blockquote data-quote="Dr. Harry" data-source="post: 663550" data-attributes="member: 5468">Shadows&nbsp;&nbsp; Your logic is correct.&nbsp; Theangular size of a distant object can be given as:angle(&quot;) =(d/D)*206,265where a is the angle in seconds of arc, d is the diameter of the object (in this case, Earth), D is the baseline distance (I used the 751 Kkm), and 206,265 is the number of arcseconds in one radian.&nbsp; Even at the farther distance, the Earth would have an angular size of 58' of arc, or almost a full degree.&nbsp; Since the Sun's angular size at the Earth's orbit is about 30', eclipses are possible.&nbsp; The size of the Earth's umbra at this distance would have a radius of 3,450 km -- just a bit more than Mars' radius of 3,394 km.&nbsp; Total eclipses are possible, but in a world like ours with the Moon's orbit at an angle (if about 5 degrees) to the plane of Earth's orbit, and the two points where the orbit crosses this plane (the line of nodes) precessing, a total eclipse would be very rare -- but, hey, it's your world.</blockquote>

[QUOTE="Dr. Harry, post: 663550, member: 5468"] [b]Shadows[/b] Your logic is correct. Theangular size of a distant object can be given as: angle(") =(d/D)*206,265 where a is the angle in seconds of arc, d is the diameter of the object (in this case, Earth), D is the baseline distance (I used the 751 Kkm), and 206,265 is the number of arcseconds in one radian. Even at the farther distance, the Earth would have an angular size of 58' of arc, or almost a full degree. Since the Sun's angular size at the Earth's orbit is about 30', eclipses are possible. The size of the Earth's umbra at this distance would have a radius of 3,450 km -- just a bit more than Mars' radius of 3,394 km. Total eclipses are possible, but in a world like ours with the Moon's orbit at an angle (if about 5 degrees) to the plane of Earth's orbit, and the two points where the orbit crosses this plane (the line of nodes) precessing, a total eclipse would be very rare -- but, hey, it's your world. [/QUOTE]

Verification