15 replies to this topic

[Dan876876]

Hi,

 

I managed to view a 22h moon with a 60mm telescope, on may 27 near the 48N parallel.

I'm reading it's difficult near summer at higher latitude, but this didn't seem too difficult.

 

On june 25th. there should be a thinner one, about 15h old.

This time it would not be a spur of the moment, I plan for a good site (45N) and a 102mm, but right at solstice, and that young, am I facing impossible odds?

 

 

[B 26354]

Welcome to the astro-jungle!  

 

You might want to ask a moderator to move this thread to the "Lunar Observing and Imaging" forum... where you're likely to get more responses.

 

The "real" thin-crescent-Moon-sighting sport...  ... is to view these young (or old) Moons naked-eye... which I've been pursuing on-and-off since the 1960s. Youngest I've seen so far is 18 hours... but the one on June 25th will be somewhere around 16hrs-50mins for me... and should be possible, since at my location, the Moon will be five-degrees above the horizon, twenty minutes after sunset.

 

But you're 14.25° farther north than I am... so twilight at that time will be much brighter for you than for me, and the angle at which the ecliptic strikes your horizon will be much more shallow, as well. So with the Moon only about 3.75° north of the ecliptic, I'd say your chances are "minimal" at best... but you won't know unless you try.  

 

And unless you know precisely where to look... I'd skip the telescope, and just use whatever binoculars you might have. These days, I use planetarium software to plot where it'll be... and then when I'm in my "spot", I just scan that area of the sky with my 8x56s, which have a nice, wide 7.4° TFOV.

 

Good luck... and post back in this thread, to let us know how it went!

 

[RMay]

For me it’s not age, per se, but size. My personal best is a 0.7% full very old thin crescent Moon. Our eastern horizon is pretty great and it allows me these opportunities. The west… not so much.

Ron

[B 26354]

The percentage-of-full thing never made much sense to me, as far as being a meaningful assessment of a crescent Moon's "age" that is readily understood by the average lay-person with minimal-to-no knowledge of astronomy.

 

For me, saying that a given Moon is 0.7% full, is descriptively obscure, and difficult to relate to, in an every-day, "Oh... I can picture that" kind of sensibility. But if I first ensure that the person to whom I'm speaking understands that a "New Moon" happens when the Moon is more-or-less directly in line between the earth and the sun... and I then tell them that the crescent Moon we're looking at is only nineteen hours from when the Moon was "new", it invariably makes sense to them... and allows them to form a better understanding of the geometric relationships between the earth, the Moon, and the sun.

 

[RMay]

The percentage-of-full thing never made much sense to me, as far as being a meaningful assessment of a crescent Moon's "age" that is readily understood by the average lay-person with minimal-to-no knowledge of astronomy.

 

For me, saying that a given Moon is 0.7% full, is descriptively obscure, and difficult to relate to, in an every-day, "Oh... I can picture that" kind of sensibility. But if I first ensure that the person to whom I'm speaking understands that a "New Moon" happens when the Moon is more-or-less directly in line between the earth and the sun... and I then tell them that the crescent Moon we're looking at is only nineteen hours from when the Moon was "new", it invariably makes sense to them... and allows them to form a better understanding of the geometric relationships between the earth, the Moon, and the sun.

 

I get what you’re saying...

 

Heres a 0.8% full crescent captured on August 15, 2023 at just under 21 hours til new, and just above 2° above the horizon. It’s a challenging sport, for sure.
 

Ron

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[WillR]

https://skyandtelesc...nt-moon-record/

[RMay]

https://skyandtelesc...nt-moon-record/

Yes… another reason why I think size is as relevant as age. Sky & Telescope called the thin crescent Moon sighting of Oct 24, 2022 a “(probably…) lifetime record for a thin crescent moon sighting” as it was about to occult Mercury.

 

At 0.8% full it was tough but I caught them both at the moment of occultation, and this hand-held mess was recognized with an Editor’s Choice when I submitted it to the magazine’s web site. It was 21 hours from new and 2° above the horizon. No matter the age, I still think it’s got to be visible (and findable) in the morning/evening sky.

 

This was taken by holding my iPhone to the 16mm eyepiece of my Questar 3.5, with no mount and no tracking, and Mercury was completely hidden no more than two seconds later. An amazingly lucky grab.

 

Ron 

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[RMay]

Addendum: per WillR’s link to the S&T post, on October 27, 2019, at 16 hours 30 minutes from new and visible only from the East Coast - as you’ll see from the image below - the Moon was a 0.7% full crescent, (beating my best by 0.1%). That would have been a great grab…

 

Thanks to WillR for the link.

 

Ron

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[WillR]

Yes… another reason why I think size is as relevant as age. Sky & Telescope called the thin crescent Moon sighting of Oct 24, 2022 a “(probably…) lifetime record for a thin crescent moon sighting” as it was about to occult Mercury.

 

At 0.8% full it was tough but I caught them both at the moment of occultation, and this hand-held mess was recognized with an Editor’s Choice when I submitted it to the magazine’s web site. It was 21 hours from new and 2° above the horizon. No matter the age, I still think it’s got to be visible (and findable) in the morning/evening sky.

 

This was taken by holding my iPhone to the 16mm eyepiece of my Questar 3.5, with no mount and no tracking, and Mercury was completely hidden no more than two seconds later. An amazingly lucky grab.

 

Ron 

I would think size and age to be equivalent? If they are not, is this because of the varying distances in its orbit, size of the moon, ie.?

[RMay]

I would think size and age to be equivalent? If they are not, is this because of the varying distances in its orbit, size of the moon, ie.?

I think the key factor (others may/should agree or disagree) is that once we are, say, less than 24 hours from either side of a new Moon, is our location on Earth relative to the rising or setting Sun and the Moon’s position in the sky at those times.

The ‘age’ of the Moon doesn’t matter, per se, if it’s still below the horizon or too high in the sky to be seen.

Better knowledge welcome here…

Ron

[WillR]

I think the key factor (others may/should agree or disagree) is that once we are, say, less than 24 hours from either side of a new Moon, is our location on Earth relative to the rising or setting Sun and the Moon’s position in the sky at those times.

The ‘age’ of the Moon doesn’t matter, per se, if it’s still below the horizon or too high in the sky to be seen.

Better knowledge welcome here…

Ron

Yes, I see your point. How dark the sky is would be a factor. And of course, we don’t get a chance to observe a very new moon that often, because a 16 hour old moon might occur in the middle of the night or the middle of the day.

Edited by WillR, 09 June 2025 - 02:42 PM.

[Dan876876]

I can't measure the % of the full moon.

 

Besides, what would it be?

% of the hemisphere area we see?

% of the disk area we see?

% of the diameter the terminators pass through?

% of the max brightness we could see?

what about different terminators due to libration? 

What about the effect of perigee and apogee?

the fact that age at perigee implies a faster transit and more %? 

 

Anyhow, I regret calling it a sport, because it's really just waiting for a better moment and clear sky. No talent required. 

 

My question is just about using my time well and avoiding a trip for possibly nothing.

 

After all this thread spoiling with a dividing question out of nowhere, I decided that the 22h old I caught is good enough for me. Moving on.

 

Now, can someone bump saturn a bit to show rings? 

Edited by Dan876876, 09 June 2025 - 02:46 PM.

[RMay]

Oh, I think it’s just a casual conversation among friends where perhaps we can learn a bit; no blood spilled that I can see.

 

 

Ron

[B 26354]

Exactly.

 

My front porch and driveway have a decent view of the eastern horizon, but only down to between five- and eight-degrees of altitude.... so "old" Moons are a little tough. But to view these western "young" Moons, I have to set up in a parking area adjacent to the mobile-home park's clubhouse... so I usually get a number of passers-by asking me what I'm up to. My normal response is something like, "Oh... I'm trying to catch sight of a really thin crescent Moon. It's just one of those silly games that amateur astronomers like to play".

 

And every once in a long while, that comment will succeed in arousing someone's curiosity, and make them stick around. That's when I ensure that they understand what a "new Moon" is, and I then explain that the object of the game is simply to spot a crescent Moon as close to the time of New Moon as possible... and that what makes it difficult, is that the sky is still in the midst of morning or evening twilight.

 

For me, a big part of the appeal of this sort of activity is just the beauty and tranquility that a low-hanging, barely-visible crescent Moon evokes. But the fact is -- simply because they're difficult to see, even when you know where to look, and what you're looking for -- most people don't ever notice these really-thin crescent Moons... or even realize that it's possible to see them. So there's also a very special thrill that comes when I'm lucky enough to be able to share one of those views with someone who's never seen such a thing before. And for that reason... along with some sort of photo setup, I always have my 8x56s with me for hand-held scanning-and-finding, and my 15x70s on a photo-tripod... so that once I've successfully found the crescent and started taking photos, I'll keep it in the 15x70's FOV as well, so my visitor can enjoy an enlarged and steady view.

 

Quite honestly... the expression of shock and surprise and delight that comes from someone who's never seen such a sight before through a large and powerful binocular... and then to be shown that they can see it "naked eye"... is one of those things that just makes life worth living.

 

[Dan876876]

A compass is fair and site-independent but limited in the dark, and aiming with a line to something obvious miles away is faster and more precise.

 

I use stellarium for getting the azimut, then I use googleearth's "ruler" to find some object matching the azimuth on site.

[RMay]

A compass is fair and site-independent but limited in the dark, and aiming with a line to something obvious miles away is faster and more precise.

 

I use stellarium for getting the azimut, then I use googleearth's "ruler" to find some object matching the azimuth on site.

I’ll have to try that. For this month’s upcoming old moon rise on the 24th (it should be coming up at one percent full, which should hopefully be not too difficult to spot), I’ll be using Venus and Capella as my ‘stellar’ landmarks, and scan the horizon at ground level. When the sky sky is clear, that method seems to work pretty well.
 

Also, below is another one percenter from last month. Easy, right!? We’ll see…

 

😉

 

Ron

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