What would oxygen or nitrogen snow look like?
I don't know if there would actually be oxygen and nitrogen snow. I would think under those circumstances, there might be carbon dioxide  snow, but the rest of the atmosphere would probably liquify first, there may be oxygen and nitrogen rain with some hail or sleet, but snow? Not sure it would happen.
If it did, oxygen and nitrogen snow would be different from our normal water based snow because of the absence of hydrogen bonds.
Individual snowflakes hexagonal in shape would not form, as this is a function of hydrogen bonds and this would not happen with oxygen or nitrogen. Water ice is also less dense than liquid water because of the way hydrogen bonds cause &quot;voids&quot; in the solid structure. This would not be the case with oxygen and nitrogen. So you'd probably get something more like needles than snowflakes.
Also, solid oxygen is blue as noted by Ed V below, so blue snow if it happens at all.
Qualifier:
If the earth is out there (beyond the orbit of Pluto) long enough, enough of the atmosphere would eventually freeze and the pressure may drop below the triple point of nitrogen. If that happens nitrogen would sublimate, then fall as snow as temperatures fluctuate.
But even Pluto's surface temperature and pressure is above the triple point of oxygen most of the time (temperature does sometimes drop below though) so any oxygen in the atmosphere would probably fall as rain (blue rain) or possibly hail/sleet rather than snow.
Another thing to remember is that if the atmospheric pressure is that low, there won't be much drag/resistance either, so no &quot;softly drifting&quot; snow. Those needles will reach terminal velocity pretty damn fast and shatter on the ground.