Astrology question about lumens and moonlight, please help =)

Hello folks,

I wonder if any kind soul could help me out with what to most people will
seem like realllllly... strange question. If you were trying to fake a moon
from 2000 metres away, what sort of size "fake moon" and lightsource would
you need? I've gotten as far as to work out that the "fake moon" would have
to be about 2 metres or so in diameter - as for the light wattage (lumens?)
I'm completely in the dark.

If you want to know why I'm asking this question, it's because I'm an
amateur entomologist - basically I catch, record and then release moths.
Migrating moths fly at about 2000 metres high (to catch faster air
currents), ergo, to get them to land near you to record what's going on you
need a "fake moon".

Many thanks,

Johan

Starting off with the word "astrology" in this group will probably get you
nowhere fast.

"Astronomy" is what gets positive results around here.

It's a good and interesting question that someone here (not me) might have
an answer for but not when you
include "astrology" as part of your subject title.

Try again, remove astrology and see what happens.

Good luck,
F Marion

Wel, I could calculate the Lumen rating for you, but first you have to
end your confusion about the differences between astronomy and astrology.

astronomy is a science, while astrology is complete nonsense.

Matthew Ota

nass wrote:

Hello folks,

I wonder if any kind soul could help me out with what to most people will
seem like realllllly... strange question. If you were trying to fake a moon
from 2000 metres away, what sort of size "fake moon" and lightsource would
you need? I've gotten as far as to work out that the "fake moon" would have
to be about 2 metres or so in diameter - as for the light wattage (lumens?)
I'm completely in the dark.

If you want to know why I'm asking this question, it's because I'm an
amateur entomologist - basically I catch, record and then release moths.
Migrating moths fly at about 2000 metres high (to catch faster air
currents), ergo, to get them to land near you to record what's going on you
need a "fake moon".

Many thanks,

Johan

In article ,
nass wrote:
Hello folks,

I wonder if any kind soul could help me out with what to most people will
seem like realllllly... strange question. If you were trying to fake a moon
from 2000 metres away, what sort of size "fake moon" and lightsource would
you need? I've gotten as far as to work out that the "fake moon" would have
to be about 2 metres or so in diameter - as for the light wattage (lumens?)
I'm completely in the dark.

The problem is, the fake moon would get bigger as the moth flies towards
it, which I imagine might confuse the poor bestiole. And I can't quite
see how you convince the moth to track on the fake moon rather than the
real one, since presumably it's started off tracking the real one.

So, you want an object which from 2km away is as bright as the Moon.
The Moon is a sunlit rock, so you want to light the object up as brightly
as sunlight would; which for a 1m^2 rock requires about 1000 watts.
Which seems likely to fry moths crispily.

I must be on the wrong lines here.

Tom

On Sat, 25 Sep 2004 20:01:05 +0000 (UTC), "nass"
wrote:

I wonder if any kind soul could help me out with what to most people will
seem like realllllly... strange question. If you were trying to fake a moon
from 2000 metres away, what sort of size "fake moon" and lightsource would
you need? I've gotten as far as to work out that the "fake moon" would have
to be about 2 metres or so in diameter - as for the light wattage (lumens?)
I'm completely in the dark.

If you want to know why I'm asking this question, it's because I'm an
amateur entomologist - basically I catch, record and then release moths.
Migrating moths fly at about 2000 metres high (to catch faster air
currents), ergo, to get them to land near you to record what's going on you
need a "fake moon".

My impression from casual observation is that a moth's visual and behavioral
wiring is pretty simple- they will fly toward the brightest source around. I'm
not at all certain they care about the size at all. The actual wattage you need
to compete with the Moon from 2000 meters away depends on the angle you want to
illuminate. If you intend to illuminate a wide angle, you'll need a few thousand
watts. You'll also need a shield to keep the moths from burning themselves up on
the lights. If you have any amateur astronomers living within a few miles,
you'll also need a shield to protect your source from BBs, bullets, rocks, etc.

Perhaps you could make do with something like a narrow angle spotlight, 100W or
less, directed upwards and just intercepting part of the moth migration.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

"nass" wrote in message
...
Hello folks,

I wonder if any kind soul could help me out with what to most people will
seem like realllllly... strange question.
snip

I hope you get an answer to your question, and in the meantime, perhaps you
can answer one of mine.
Why do creatures that have evolved to live in the dark fly towards a light?
Sometimes the brightest thing for fifty yards in any direction is my screen,
and hordes of tiny flying things, so tiny that they can fly through my
flywire screens with their wings fully extended, dash themselves against it.
Do these same creatures vainly try to reach the moon, and perish in the
airlessness of the Stratosphere?

T.T. says...

I hope you get an answer to your question, and in the meantime, perhaps you
can answer one of mine.
Why do creatures that have evolved to live in the dark fly towards a light?
Sometimes the brightest thing for fifty yards in any direction is my screen,
and hordes of tiny flying things, so tiny that they can fly through my
flywire screens with their wings fully extended, dash themselves against it.
Do these same creatures vainly try to reach the moon, and perish in the
airlessness of the Stratosphere?

The insects navigate by holding the light at a certain angle. In the
case of the moon this results in straight flight. If the light is a
lot closer, the insect either spirals away or spirals towards it,
depending on what angle it is trying to hold. The 50% of insects that
spiral towards the light end up hitting it.

On Sun, 26 Sep 2004 04:54:56 GMT, "T.T." wrote:


[...]

Why do creatures that have evolved to live in the dark fly towards a light?

That's how they know which way is up.

Nick


--
Nick Theodorakis

contact form:
http://theodorakis.net/contact.html

Most nocturnal animals don't. If you want to frighten away frogs or
badgers, turn on a light. Other animals are simply indifferent to
artificial lights, like bats and nightjars, and will happily feed on
the insects attracted to them but otherwise ignore them.

As for insects like moths, the simple answer is that we don't know.
There are numerous theories, one of the more popular being that they
use the Moon as a navigation aid.

http://www.butterfly-conservation.or..._faqs/004.html

Since the Moon is both very distant and constantly moving, there's no
risk a moth flying towards it will end up in the stratosphere. Quite
the reverse, it probably encourages the moth to plot a more or less
straight line path through the night. Why it would want to do this is
a mystery.

A similar problem exists with sea turtles, which when the hatch are
attracted to the sparkling moonlight on the sea. With the development
of beach-side hotels and nightclubs, a terrible number of baby turtles
head in the wrong direction, attracted inland instead of towards the
sea, where they get crushed by cars, eaten by predators, and otherwise
lost.

Cheers,

Neale

"T.T." wrote in message ...
Why do creatures that have evolved to live in the dark fly towards a light?

= *puts his dunce hat on*

Apologies folks, I feel suitably chastised for my
erroneous title. This was my query, which still stands:

Hello folks,

I wonder if any kind soul could help me out with what to most people will
seem like realllllly... strange question. If you were trying to fake a
moon
from 2000 metres away, what sort of size "fake moon" and lightsource would
you need? I've gotten as far as to work out that the "fake moon" would
have
to be about 2 metres or so in diameter - as for the light wattage
(lumens?)
I'm completely in the dark.

If you want to know why I'm asking this question, it's because I'm an
amateur entomologist - basically I catch, record and then release moths.
Migrating moths fly at about 2000 metres high (to catch faster air
currents), ergo, to get them to land near you to record what's going on
you
need a "fake moon".

Many thanks,

Johan

To answer some questions and concerns:

* It is believed that moths use the moonlight to navigate by. They keep the
moon at a certain angle over their left shoulder.
* The creatures would not fry: they would not be able to see or reach the
bulb(s) as I'd envisaged surrounding the whole thing with plastic. Ie a huge
plastic sphere 2m in diameter in my garden (Eccentric? You bet!) with an
adaptation of a "robinson trap" below. I do not believe in killing the
creatures, even for rare catches or recording. That's what digital cameras
are
for.


Your help is greatly appreciated!

Regards,

Johan