The sun and moon play hide and seek on Thursday, as the lunar silhouette glides across the solar disk in a partial solar eclipse visible across much of North America.

The shadow of the rare partial solar eclipse first falls on Siberia's Kamchatka Peninsula at 2:37 p.m. EDT on Thursday, October 23. Local viewing times will vary as the moon's shadow travels east over much of Canada, Mexico, and the United States, with a sunset eclipse visible from eastern states.

"The farther north and west you are on the continent, the more of the sun you will see covered," says astronomer Jay Pasachoff of Williams College in Massachusetts, a National Geographic Society grantee. As long as