Moon halo

[AstroBug]

There's a moon halo in Melbourne right now (about 11.15pm local time). Is that a local phenomenon or can it be seen in other parts of the country?

[ballaratdragons (Ken)]

Yep, it looks magic up here too Brett!

I keep looking at it each time I go out for a smoke

The Moon Atmospheric ring can happen anywhere. It is caused by a particular ice crystal in the air.

[AstroBug]

Thanks Ken,

I might have to go out for another one myself (and a look at the moon) . I wonder how far and wide the conditions affect the halo.

[ballaratdragons (Ken)]

Hmmm, I just tried to photograph it with my pocket digital camera. No go

Not that I expected it to work with this camera
But ya never know if ya don't have a go

[erick (Eric)]

Yes, it was a lovely sight. I got home late (midnight) and looked up, hoping for clear skies so I could get the scope out. Transparency low, onlt a hint of brightest stars, but a full halo around the Moon - very strong! Wished I had a proper digital camera! Saw the same effect last Sunday evening up the Dandenongs. It's the right time of year for this, I guess.

[mill (Martin)]

Tried to make a photo earlier in the year of a halo around the moon with a digital camera but no go.
It is really hard to get the halo to show up

[iceman (Mike)]

You need a long exposure to photograph the halo, so that means a tripod.

It will also mean the moon itself gets overexposed.

[erick (Eric)]

Originally Posted by iceman

You need a long exposure to photograph the halo, so that means a tripod.

It will also mean the moon itself gets overexposed.

Yes, I figured you'd need to combine two exposures. Would the halo require more exposure time then one would take without tracking - but I guess the diffuse nature of it means a little bit of "trailing" wouldn't be a problem?

[iceman (Mike)]

You definitely wouldn't need tracking. I imagine the halo would only require an exposure of 2-8 seconds, depending on the ISO used.

Also given that the exposure requires a short focal length lens, you won't see any trailing for at least 15 seconds on a fixed tripod.

If you wanted to combine two exposures, you'd have to do some careful blending in photoshop to blend the two layers (using selective feathering). Otherwise you could just paste the cutout of the full moon exposure over the top of where it should go in the halo exposure.

The idea is to make it not look too sharp and cutout, ie not too obviously processed.

[erick (Eric)]

Thanks Mike