Acid rain indicated by a dark circle around the moon?

Have you noticed dark circles around the moon?

Could it be acid rain? A dark circle appeared around the moon! Oh no. Ignore emails claiming this means acid rain is on the way.

Circles of such nature are nothing special — they take place regularly, and their appearance has nothing to do with acid rain. This optical illusion comes about when there's a combination of very clear skies and fine ice particles in the upper atmosphere.

"Be careful from 20th to 28th of this month (March). There is possibility of an ACID RAIN. The dark circle appeared around the moon on 17th last month is an indication. Apparently this happens once in 750 years. It rains like normal raining. It may cause skin cancer if you expose yourself."

All bunk!

This information is not from NASA.

"From today till the 28th, please be careful not to be caught in the rain. This acid rain is the biggest since 750 years ago and stands a good chance of giving you skin cancer."

Bull!

"A volcano that erupted in Europe has spewed a large cloud of volcanic ash into the atmosphere to form a highly acidic layer."

April 2010 versions of the acid rain warning tied it to the 15 April 2010 volcanic eruption in Iceland that sent a large ash plume into the skies. Said cloud shut down airports in more than 20 European countries, some for up to five days.

Acid rain does not cause skin cancer, nor did the National Aeronautics and Space Administration (NASA) send out this alert.

From Snopes...