31415 Wat, do you use a lightning triggering app for your excellent lightning photos? Nope!  I don't think such an app is necessary.  I just set a long (15") exposure, press shutter, hope for lightning, and repeat. :)   I could have used an intervalometer to trigger the shutter repeatedly for ...

evildrganymede wrote:

Qr Bbpost pure water is generally colourless too...

Pure water is not colorless.    It is intrinsically slightly blue, which becomes apparent when viewing through a long (few meters) column of it.

As shared in the  show your work thread , last night we had incredible storms pass through western Washington, with cloud tops reaching 35-40 thousand feet (10-12km) and bolts striking down every few seconds for over an hour.  Any lightning is rare here since it is hard to get the atmospheric instab...

31399 If liquid N2 is totally colorless as it says everywhere, then how would a planet covered on deep oceans of pure liquid nitrogen look like? This is an interesting question.  I have looked around, but cannot seem to find literature on the absorption spectrum of liquid nitrogen over visible wave...

An intense thunderstorm just rolled through about an hour ago, with many cloud to ground strikes.  Lightning is so uncommon here (maybe you'd hear one or two faint rumbles of thunder in a given summer), so this was a rare treat, and I was thrilled to try my hand at lightning photography again -- som...

Another nice day in the mountains.  Went high contrast with this shot and love the effect.

That is an incredible result,  Phunnie .  I absolutely love that color palette. :) Last night I also did some astrophotography, though not with such nice equipment.  A quiet, beautiful night under the stars in the North Cascades, with the Canon Rebel T3 and a tripod. https://i.imgur.com/XPzlsy4.jpg

31181 If we had an Earth around a hotter sun in a habitable, say an F, A, or O star, would we get sunburn easier? Yes, we very probably would, for just the same reasons.  The hotter the star, the larger the fraction of its light that comes through UV, so even if we kept the total amount of sunlight...

31177 If you had an Earth around a hotter star and it's in the habitable zone, will the star be the same (similar apparent brightness in the sky as the sun or not? Similar, but not exactly the same.  In fact, if the star is either much hotter or colder than our Sun, then from the habitable zone its...

Slightly aside, if we consider quantum mechanical systems like electrons orbiting protons in atoms, then those orbits are stable against gravitational decay.  In fact they are also stable against electromagnetic decay.  A classical calculation would suggest that because an electron orbiting a nucleu...

31136 Is there such thing as a stable orbit, or do the laws of physics forbid this? As in, any two body system should lose energy to gravitational radiation right? Yep, you're completely right.  All orbital motion generates gravitational waves, which while for most situations is a really, really  s...

31138 40 MJ... that's actually very close to 1/24.96 of a solar mass (that would be 41.96 Jupiter masses exactly)? I'm assuming that's not a coincidence? Good observation!  It is very close and not by coincidence.  It's not quite correct that the rule is "total mass of everything in the orbit ...

evildrganymede , good question!  In all my calculations and figures I treat the particle as massless (a good approximation if it is say, a spacecraft or asteroid as a Trojan of a planetary body).   If it is massless, then stability about the L4 and L5 points occurs if the primary mass is at least 2...

31099 Wat, I heard PBS is going to do something about the different predictions for the acceleration of the universe (the differing values of the Hubble constant), did they mean what we had already talked about or is it something new? I think you might be mixing two things.  The Hubble constant is ...