Ah, much better.  This man can properly summon UFOs.

Where are the flying saucers?  I just see bright lights.  Signal flares by the looks of it (and much more than just a couple miles away). Sodium would easily explain the golden color.  I would love to be proven wrong, someone should bring a spectrometer to the next sighting.

Round trip airfare between Seattle and Tokyo: ~$1000
Gamma ray source and detector:  a few hundred dollars
Summon a flying saucer to study:  ???

I feel that Chelyabinsk should be a stronger motivator for asteroid impact awareness, since it was so well documented, did do damage to a populated area, and if that object had been a little larger or had come in at a steeper angle, it likely would have devastated the city.

28764 Interesting!   So hypothetically if we were floating in space half a mile from the Orion Nebula we wouldn't see color in it like we can see in photos?  Even if it covered half the visible sky?  I figured you could see colors more readily up close because the object would appear much large...

28749  Would the whole atmosphere explode or something if I opened a lighter on the surface? No.  For the atmosphere itself to ignite the oxygen-methane mixture needs to be sufficiently close to the stoichiometric 2:1 ratio.  The best way to see this is with a  flammability diagram.   In this parti...

This isn't quite the same as ultraviolet photography, where you see the world with ultraviolet eyes.  Rather, think of it as normal photography, but with an ultraviolet light source.  F luorescence is when that short wavelength UV light is absorbed and then the energy re-emitted it at longer, usual...

It's a thought.  I normally only rock hunt during the day since that makes most objects of interest easier to find, but fluorescence is too dim to see in daylight.  Also many objects I'm interested in don't fluoresce, like petrified wood.  Hunting specifically for fluorescence at night might be inte...

The agate/chalcedony collection continues to grow, and now contains a few fluorescent specimens.  Here they all are under incandescent light. https://i.imgur.com/6BJ4SmR.jpg    And now illuminated under 405nm (nearly ultraviolet) light. https://i.imgur.com/kQOY9za.jpg Fluorescence is always a nice s...

28656 China is projected to reduce their CO2 output by two thirds by 2030 and that will help a lot. Do you have a reliable source for this projection?    The most recent large metastudy of projections for China's CO2 emissions that I have seen is this one from 2015: A review of Chinese CO2 emission...

I just came across this nice video by ESO.  It uses (correctly cited) some footage from Space Engine.

28563 And further digging led me to this article. This paper is relevant too.  What the authors (including Adam Rie ss, who is a big name in this field!) are checking is whether some effects of local structure in the universe could be causing our estimates of the uncertainties in the measurements i...

28560 But I couldn't find the paper this supposedly is based on.  Does anyone know where this comes from? Probably this:   Cosmological constraints from the Hubble diagram of quasars at high redshifts . PBS Space Time has a good summary of it, and in the cosmology thread I also give some further in...

Excellent!  With more events like these, we might independently measure the value of the Hubble constant with better precision, and possibly resolve this old discrepancy.