NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Mars occultation or close approach tonight
From: Russell D. Sampson
Date: 2023 Jan 31, 12:17 -0500
From: Russell D. Sampson
Date: 2023 Jan 31, 12:17 -0500
Frank
Interesting problem. I was watching the moon approaching Mars last night too but was interrupted by clouds and sleep.
Four things come to mind regarding the apparent slowness of the moon; 1) apogee/perigee and Kepler’s laws (apogee on February 4), 2) parallax due to the spinning Earth angular rotation rate vs angular orbital rate of moon (15:1) which is at maximum when moon is at meridian, 3) measurement uncertainty of visual observations possibly due to the gibbous phase and 4) moon near a node so moon is approaching Mars at an angle to the ecliptic and thus its component of motion along ecliptic is at a minimum (ascending node January 28).
Such a fun and complex problem.
Russell Sampson
Sent from my iPhone
On Jan 30, 2023, at 23:31, Frank Reed <NoReply_FrankReed@fer3.com> wrote:
Anyone watching?? I checked at 6:00pm (Eastern US time)... At that time, the distance from Mars to the center of the Moon was just about 2.5° by visual estimate, counting Moon diameters. And now, at 11:00pm (EST), it's about 1°. Hmm... five hours elapsed, but the distance has changed by only 1.5°. We know that lunar distances change at a rate of just about 0.5° --that's one average apparent lunar diameter in one hour. Not even close! So what's going on?? Why is the lunar distance changing at the "wrong" rate?
Frank Reed
PS: The image of Mars is just for fun!File:
