[Helix]

Since ultraviolet radiation is blocked by Earth's atmosphere, this kind of photography must be done from orbit.

Beautiful picture! Did you know that some insects can see well into the UV range? I wonder if that was ever a useful ability on Earth.

[petuniasevan]

Like honeybees, for instance.
Here's a chart of wavelength sensitivity for human vision and bee vision.

This is a comparison of wavelengths visible to humans and bees.
The range of vision for the bee and butterfly extends into the ultraviolet.
The petals of the flowers they pollinate have special ultraviolet patterns
which guide the insects deep into the flower.

This doesn't contradict my earlier assertion that UV imaging must be done from orbit; obviously a little UV gets through. It's what gives you a tan (or sunburn). It's just that 99% of "soft" UV is blocked, and higher-energy "hard" UV is 100% blocked, as are X-Rays.

[petuniasevan]

Daylilies in normal daylight visible spectrum.

Same daylilies in UV light.

Although we can't be sure exactly HOW UV light appears to bees, it seems that the UV image above shows dark central regions in the flowers which guide the bee to the nectar.

[petuniasevan]

Ordinary yellow weedy dandelions become rare jewels in UV light.