The blue glow that surrounds the blue Horsehead's eye — and other stars around the image — is a reflection nebula composed of fine dust.

环绕着蓝色马头的眼睛部位的蓝色光芒——与周围其它恒星——是一个由细尘埃组成的反射星云。

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But they glow red under ultraviolet light, and the dogs' nails and abdomens, which have thin skins, look red even to the naked eye.

但在紫外线的照射下，它们会发出红光，尤其是爪子和皮肤很薄的腹部，用肉眼都能看出发红。

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When shorter wavelengths of light, invisible to the human eye, hit the gold nanoparticles, they get excited and start to glow violet.

当金色纳米微粒收到肉眼不可见的更短波长的光照射时，它们将被激发并发出紫光。

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All Max needed to do was sail north for a few hours and keep his eye on the dim glow of the city in the distance.

NEWYORKER: Max at Sea

If the light were not infrared but were instead in the visible spectrum, there was enough of it that the naked eye could have seen a glow, according to Phaedon Avouris , manager of nanometer scale science and technology at IBM (nyse: IBM - news - people ) Research Laboratories in Yorktown Heights, N.

FORBES: IBM Makes Molecule-Sized Light

Along with key landmarks such as Big Ben, the Houses of Parliament, and The London Eye going dark, the quadrocopters will turn off their glow in support of Earth Hour.

ENGADGET: Quadrocopter fleet stuns Londoners with giant hovering Star Trek logo (video)