Venus at 1 micron

[N1]

Some experimenting last Friday with smaller, simpler and cheaper equipment than what is commonly used for this purpose did reveal a little bit of the nightside surface signature of Venus in the NIR by sufficient cranking of the exposure.

6" f/8 Synta Newt, ASI120M, Pixelteq 1010/38 band pass filter

[Dave882]

Very interesting thanks for sharing Mirko. Wondering if a composite image would be possible :question:

[N1]

Thanks Dave - doable I expect but the crescent does burn out a lot of area you'd need for a proper one.

[astronobob]

Interesting & well caught Mirko,

We know on the moon is called 'Earth-Shine' eh, But what is it on Venus, would it still be Earth's-Shine, just asking because the distance is way further,, Earth Moon only 384.400klms but Earth to Venus at closest point is 38 million klms which calculating is very close to 100 times further away, and after doing the math, 100 times further away seems somewhat feasible now actually,
1st thought was a thousand times or more, ahhh, learning every day

Good show and post :thumbsup:

[N1]

Hi Bob,

While this does look a bit like Earthshine, it has a very different cause. It's the thermal signature of Venus' surface glowing in the near infrared, which can then be picked up by cameras with appropriate filtering as Venus' cloud deck is relatively transparent around some wavelengths, incl 1,010nm. The technique has been practiced by amateurs since the early naughts. For a good example of what's possible check out the work of Australians Anthony Wesley and Phil Miles (https://britastro.org/wp-content/uploads/sites/jbaa_11273.pdf), who have been very successful with this kind of imaging. We've been using other equipment as well incl significantly larger optics, but that data is still being worked on. This rig was set up alongside specifically to see what's possible with basic gear.

On the subject of light being refrected off the night-side of Venus, there have been occasional reports of 'ashen light' (https://www.skyatnightmagazine.com/space-science/ashen-light-mystery-venus-dark-side-glow), which may indeed be caused by Earth (though other theories exist). I've yet to observe it (visually or otherwise), but I agree with you it may actually be a thing. We know Venus can cast shadows on the night side of Earth, i.e. visibly illuminate the ground, so I don't see why a brilliant gibbous Earth seen from Venus (-6th mag or thereabouts??) couldn't do the same thing on its cloud deck, especially on such a high-albedo canvas.

Fun stuff

[Dekker]

That's a very interesting experiment Mirko; makes me want to try it for myself.


Upon searching for the Pixelteq bandpass filter, I stumbled upon an amazing image from one Tom Williams on Astrobin:
https://app.astrobin.com/equipment/explorer/filter/14191/pixelteq-nir-bandpass-filter-1010nm-fwhm-38nm
https://app.astrobin.com/i/psuedp


Apparently Tom used an additional IR850 filter because there was some green & blue light leaking past the Pixelteq. The extra filter may help a little in reducing the glare from the sunlit side.

[astronobob]

Thnx for your time and information Mirko, quite eye-opening in my reality, well, to the degree of what is capable within the amateur astronomers world these days, not forgetting the creaters of such filters etc too,,,
Good work, keeping the ball rolling in learning further light principles and developing new techniques in our own backyard, , :thumbsup:

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This is a great addition Derrick, extraordinary results from Tom if I may say so.. :thumbsup:

[N1]

Fantastic results there, and yes, we've been experimenting with various filter stacking arrangements too. Our biggsest challenge around here, by far, is the seeing.

[Dekker]

Understandable, since you would want to minimise the sunlit portion of Venus, hence take it as close to conjunction as you dare, which means it would be very low on the horizon.

[multiweb]

Nice catch :thumbsup: The earth albedo makes sense too.

PS: love your backyard. Looks like it would get bloody cold.