Beautiful solar halo observed in Mexico City on the 28th of May, 2015.
More from Chalkdust
The Spirit of Mathematics
We review the ninth of this year's nominees for Book of the Year
Headscratchers
We review the eighth of this year's nominees for Book of the Year
A Year in Numbers
We review the seventh of this year's nominees for Book of the Year
Short Cuts: Maths
We review the sixth of this year's nominees for Book of the Year
How to Expect the Unexpected
We review the fifth of this year's nominees for Book of the Year
The Secret Lives of Numbers
We review the fourth of this year's nominees for Book of the Year