Why does our skin get dark and our hair get light under the sun?

In both cases, the sun breaks melanin, responsible for the color of hair and skin. The difference is in the fact that hair is not living, compared to skin. When the pigment is broken, it is not replenished in hair, so the latter gets lighter. Skin "answers" to the sun with a stronger replenishment of melanin, making the color darker.

International Sun Day || May 03,2017

Temple of the Sun, Palenque

The Majestic Kingsdown beach is lit up with the afternoon sun

A halo around the sun is seen over the Capitol, in Sacramento, Calif. 

Sun wearing coolers..

Colorful Sun and Moon with Jewels

Don’t Panic But A Huge Black Mark Has Appeared On The Sun... yahoo.com

'Don’t Panic But A Huge Black Mark Has Appeared On The Sun' on Yahoo News UK. It’s the size of 50 Earths

uk.news.yahoo.com/don-t-panic-but-a-huge-black-...

The ring around the Sun found on Sep 28 2015 in Coimbatore, India...

The International Space Station, with a crew of six onboard, is seen in silhouette as it travels across the face of the sun at roughly 5 mps, Sunday, Sept. 6, 2015, as seen from Shenandoah National Park, in Front Royal, Va. Onboard are NASA astronauts Scott Kelly and Kjell Lindgren; Russian cosmonauts Gennady Padalka, Mikhail Kornienko, Oleg Kononenko, Sergey Volkov; Japanese astronaut Kimiya Yui; Danish astronaut Andreas Mogensen and Kazakhstan cosmonaut Aidyn Aimbetov.