
NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Raw data for bubble
From: Bill B
Date: 2007 Mar 21, 16:22 -0400
From: Bill B
Date: 2007 Mar 21, 16:22 -0400
> From: "Bill Noyce"> I'll take a shot at answering some of Bill's questions... > > The "magic number" 0.2724 isn't an angle, it's simply the ratio > moon_radius / earth_radius > SD is the angular distance of the moon's radius as seen from the > earth, and similarly HP=SD/0.2724 is the angular distance of the > earth's radius as seen from the moon, which is another way of > describing the parallax of the moon at the horizon. When we're on the > line from the center of the earth to the moon, parallax is zero (and > Ho=90 degrees). For intermediate cases, cos(Ho) represents how far > from that centerline we are, and thus how much of the HP to include. Thank you Bill. I guess what mislead me was the N.A. presentation of the 0.2724 constant which is does present as an decimal degrees. I am still pondering it. Bill N. --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to NavList@fer3.com To unsubscribe, send email to NavList-unsubscribe@fer3.com -~----------~----~----~----~------~----~------~--~---