Comments on: We don't know the ocean

By: A. Karttunen

A. Karttunen — Thu, 13 Nov 2014 21:39:58 +0000

This indeed was a great post, coinciding with an almost mystical insight I had about another field of knowledge.

Also Kevin Raskoff’s photo of Marthus Orthocanna
(which you have removed now) crowned it.
Fortunately, I found it again, from here:
http://eu.lumas.com/pictures/kevin_raskoff/hidden_ocean_8_brmarrus_orthocanna/

As what comes to space, and its seas, please see also this:
http://saturn.jpl.nasa.gov/news/cassinifeatures/feature20141110/

By: RR Helm

RR Helm — Fri, 07 Nov 2014 01:05:11 +0000

In reply to Eric Rehm. 450 nm wavelength? So the deep sea is tinted slightly green?!?! Is that what this means?

By: Tharaka Sriram

Tharaka Sriram — Thu, 06 Nov 2014 20:02:46 +0000

Very well written and indeed- what people like to see as the ocean is far more than the beaches to hang out, the fancy coral reef diving etc. It is home to far more creatures that we will ever know and probably never understand.

By: Alistair Dove

Alistair Dove — Thu, 06 Nov 2014 13:58:54 +0000

In reply to Steve H. You're absolutely right. My apologies for not crediting Kevin.

By: Steve H

Steve H — Thu, 06 Nov 2014 02:20:05 +0000

You should credit Kevin Raskoff for his photo.

About the comment on darkness, it is functionally dark down there, even at 1000 meters, other than bioluminescence. You can’t give a flux number and say it is above detectability for some fish if those photons are isotropically emitted and diffusely distributed. Detection is a function of contrast vs background, and that would be the background.

By: Eric Rehm

Eric Rehm — Wed, 05 Nov 2014 20:22:57 +0000

“The other 11,450 feet consists of pitch dark and perpetual blackness…” Not so. From Light and Water (Mobley 1994): Cherenkov radiation from relativistic electrons emitted in the decay of naturally occurring potassium-40 ions generates about 1.2×10^6 visible photons/m^2 /s at all depths in very clear waters. Their nighttime measurements to depths of 4300 m in clear waters near Hawaii showed a typical background “glow” of order 10^7 photons/m^2/s, which includes bioluminescence as well as sources such as potassium-40 decay. Thus it is never completely dark at even the greatest depths, even though no solar photons are present. If we assume photons of wavelength 450 nm, then 10^7 photons/m^2 s corresponds to 4×10^-12 W/m^2 which, interestingly, is just *above* the estimated threshold for detectability by some deep-sea fish. “[Emphasis added.]