I stumped Perplexity. Can anyone else help?

[robkelk]

I stumped Perplexity with the question "When was the first sunrise after September 13, 2018 at Tycho Crater on the Moon?"

I can’t determine an exact clock time or Earth date for that specific sunrise with the information and capabilities I have.

To answer precisely, one would need:

• A detailed ephemeris for the Moon’s rotation and orbit.
  
• The selenographic coordinates and local topography of Tycho Crater.
  
• Software that can propagate the lunar geometry from 13 September 2018 onward and solve for when the Sun’s elevation at that location next crossed from below 0° to above 0°.
  

In principle, you could get this by:

• Using a professional ephemeris package (e.g., JPL Horizons via suitable software) to compute the Sun’s apparent position as seen from Tycho’s coordinates as a function of time.
  
• Including local horizon/topography (Tycho’s rim and central peak) to refine when direct sunlight first reaches the crater floor or central peak.
  
• Numerically finding the first time after 2018‑09‑13 when the solar altitude becomes positive at the chosen point inside Tycho.
  

Without access to those tools and data right now, I can’t give a reliable numeric answer; only this procedure to obtain it.

As one might guess from this being posted to the My Apartment Manager is not an Isekai Character forum, the exact location in Tycho Crater is TMA-1. (What, you thought that only HAL-9000 was displaced from 2001?)

Does anyone here have any of what's needed to answer my question, or know where to find it online?

[Bob Schroeck]

ChatGPT just gave me an answer it says is correct to within 10 to 20 minutes -- approximately 04:49 UTC on 9/16/2018. I just sent you an email with a link to the conversation.

[robkelk]

Thanks, Bob.

[Bob Schroeck]

No problem.

[Labster]

Using Stellarium, I got a sun crossing the 0° inclination at 2018-09-18 09:28:40Z, using Wikipedia's lat/long for the crater.  I think it would likely be later than this, because you're in a crater, so there's some hills on the horizon.

If you're at the deepest point of the crater, you're 4.7km down, in an 85 km diameter crater, so you'd get an additional angle of...

θ = tan⁻¹ 4.7 km / ( 85/2 km ) = 6.31°

But some of this will be taken up by the Moon's curvature, so let's get its portion of the circumference

42.5 km * ( 360° / 10000 km ) = 1.53°

For some reason I feel like this is the same angle as the horizon due to some geometry but I'm not going to even try without a piece of paper, just accepting the number  So depending on your altitude, you could need to get up to 4.78°, which could be as late as 2018-09-18 22:40:37Z ... though you'd see the sun on the other side of the crater first.

[robkelk]

Thanks, Brent. You and Bob agree on the date, but not the time... so I'll just have folks show up the day before and spend a day waiting for the sunrise.

(Waiting for the sunrise? Cue Les Paul... EDIT: or Benny Goodman.)