The 'Make or Break' equation

[Capt Slog]

In this month's Sky at Night magazine, there was an article about the number of nights you can observe, written out as an equation.

It was adapted from the 'Drake Equation', which estimates the number of civilizations it would be possible for humans to communicate with.

N=R_* x f_P x n_e x f_l x f_i x f_c x L
N    =    number of civilizations with which humans could communicate
R_*    =    mean rate of star formation
f_P    =    fraction of stars that have planets
n_e    =    mean number of planets that could support life per star with planets
f_l    =    fraction of life-supporting planets that develop life
f_i    =    fraction of planets with life where life develops intelligence
f_c    =    fraction of intelligent civilizations that develop communication
L    =    mean length of time that civilizations can communicate

 

But reads  N= Y x Fc x Fm x Ffr x Fbw x Fbt x Fd   where N is the total number of nights it's possible to observe.

Y = number of nights in a year, Fc = fraction of clear nights, Fm= fraction of moon free, Ffr = fraction 'free' nights, Fbw = Fraction with bearable wind, Fbt = Fraction with bearable temperature, and Fd = fraction where all equipment works.

They left one out, "F lurgy", Which is the fraction of nights you don't feel like the contents of your head are trying to drain out through your nose! (or other ailments)

The clearest night we've had in ages, with all the other factors looking good, saw me afflicted with the "too poorly to venture out".  To stay in the good books of Mrs Slog, I thought it was best to stay indoors, keep warm and watch the telly.  Ah well. 

 

Edited April 1, 2022 by Capt Slog

[keora]

From reading the article, and others that Ron Brecher has written, I imagine he's a  semi professional astronomer. So he's got more incentive to get out and look at the stars.

[SteveNickolls]

Thanks for this. After reading the article I realised all these past years I should have been double counting sessions where they straddled two dates! Never mind. Onwards and upwards.

Cheers,

Steve

[tomato]

I guess the “too ill to go out” occasions come into the term Ffr, fraction of free nights?

Based on my own circumstances as an imager, with 36% of the nights clear to date and I go out regardless of moon phase, wind (dome) or temperature(warm room) and after 8 years operation my set up is quite reliable, assuming the fraction of clear nights holds🤞I get:

N= 365x 0.36 x 1.0 x 0.9 x 1.0 x 1.0 x 0.9 = 106.

Looks like I need another hard drive….

[Ags]

Ahem! I believe I first formulated what I called the Darke Equation in 2017 and even provided a helpful online calculator:

http://opticsandalgorithms.blogspot.com/2017/05/whats-your-darke-number.html?m=1

 

Edited April 1, 2022 by Ags

[Capt Slog]

46 minutes ago, Ags said:

Ahem! I believe I first formulated what I called the Darke Equation in 2017 and even provided a helpful online calculator:

http://opticsandalgorithms.blogspot.com/2017/05/whats-your-darke-number.html?m=1

 

Certainly very similar.    But the 'weekend' factor doesn't take into account retirees 

It was annoying last night, because for the last week or more the skies have been dreadful here; what I term as a 'mustard' sky.  A lot of it is light pollution I know, but there seemed to be more dust up there than usual.  If I look outside and can barely make out Ursa Major, i know there's no point in getting out the scope.

 

 

[Ags]

Retirees have a very high weekend factor. The factor was defined as "nights without an early morning commitment". A better name for the factor could have been devised 😀

Of course the credit for applying the Drake Equation to real world problems goes to Howard Wollowitz, the noted NASA engineer.

Edited April 1, 2022 by Ags

[Ags]

15 minutes ago, Capt Slog said:

If I look outside and can barely make out Ursa Major, i know there's no point in getting out the scope.

Even on those nights, there's doubles.

[Starwatcher2001]

3 hours ago, Ags said:

Even on those nights, there's doubles.

Yeah, but what we need is a good book to help us find 'em.  🤣

[mikeDnight]

Call me silly, but I've always tended to look outside and if its clear or clearish, and I feel like observing, I go out and observe. I've used this method for the past 42 years quite successfully without ever resorting to equations of any kind. Sadly I was compelled to stop watching S@N not long after our dear Patrick passed away as it rapidly turned into generic BBC vomit after being handed over to so called academic's. How pleased I am that I missed this episode. Life's just too short!

[Ouroboros]

Damn! I had the idea of this adapted “Drake Equation” some time ago but never got around to posting it on SGL. Now someone’s beaten me to it. 😐

[Ouroboros]

20 minutes ago, mikeDnight said:

Call me silly, but I've always tended to look outside and if its clear or clearish, and I feel like observing, I go out and observe. I've used this method for the past 42 years quite successfully without ever resorting to equations of any kind. Sadly I was compelled to stop watching S@N not long after our dear Patrick passed away as it rapidly turned into generic BBC vomit after being handed over to so called academic's. How pleased I am that I missed this episode. Life's just too short!

It’s got nothing to do with telling you whether it’s clear to observe. 

[Capt Slog]

3 hours ago, Ags said:

Retirees have a very high weekend factor. The factor was defined as "nights without an early morning commitment". A better name for the factor could have been devised 😀

Of course the credit for applying the Drake Equation to real world problems goes to Howard Wollowitz, the noted NASA engineer.

I never have early morning commitments now.  I rarely wake up until 8, and don't get up properly until way after that (cups of tea etc)

 

and @mikeDnight, it was a bit tongue in cheek, I'd never bother with the equation either.

[Ouroboros]

If anything it confirms something most of us already know - how desperately infrequently the factors align to make a night out under the stars possible. 

[Guest]

They forgot to add the Ohio Skies SUCK factor to the equation, and that any good night will be on a work night when I have to get up at 0500 the next day.  

[Voyager 3]

Well the Drake equation is almost useless because most of the variables in the equation are unknown to us. What we could do is a pretty wild approximation. So yes, it's not going to come out and say anything useful like F=Gm1m2/r² or E=mc². 

[Pixies]

mis-post

Edited April 16, 2022 by Pixies
mistake

[Whistlin Bob]

On 02/04/2022 at 02:23, Mike Q said:

Ohio Skies SUCK

It's funny how we romanticise the places we visit and criticise our own. Thirty years ago I was on an exchange visa, working in Sandusky Ohio, and pretty disinterested in astronomy, when I had a night out under the stars by Lake Erie with some friends, and was blown away by the naked eye sight of the Milky Way which I'd never seen from home. In my imagination the skies of Ohio are a wonder, but maybe it was just a lucky night!!

[Guest]

5 minutes ago, Whistlin Bob said:

It's funny how we romanticise the places we visit and criticise our own. Thirty years ago I was on an exchange visa, working in Sandusky Ohio, and pretty disinterested in astronomy, when I had a night out under the stars by Lake Erie with some friends, and was blown away by the naked eye sight of the Milky Way which I'd never seen from home. In my imagination the skies of Ohio are a wonder, but maybe it was just a lucky night!!

Sandusky is just an hour or so north of me.  I will give you this.  Despite all the light pollution from Toledo, Port Clinton, Sandusky and Cleveland, when you look out over the lake....it does look very nice up there.  Not sure how that works in a State where Bortle 4 is about the best we get

[Ags]

On 16/04/2022 at 18:37, Voyager 3 said:

Well the Drake equation is almost useless because most of the variables in the equation are unknown to us.

It does a pretty good job of quantifying our uncertainty!

[Voyager 3]

6 hours ago, Ags said:

It does a pretty good job of quantifying our uncertainty!

We may never be sure in this situation. There is an infinite number of possibilities for life in infinite number of planets. We don't even know whether ET life requires a planet like us. So yeah, it's uncertainty at its best.

[bingevader]

We could shorten your F lurgy to Fmf - man flu!

I'd dispute the moon fraction too, what's wrong with observing the moon (in all but full phase)?!