Today, June 20, at 23:09 UTC (7:09 p.m. Eastern US time), the Earth's north pole will be tipped over toward the Sun as far as it can for the year. There are other ways to describe it -- the Sun reaches its maximum declination, its annual northern movement in the sky peaks, it's the longest day of the year -- but most folks just call it the summer solstice.
You can use this event to measure your latitude the Earth's tilt, if you have a stick and a protractor and clear skies and the ability to take an inverse tangent. Or you can read about past summer solstices here, here, here, and here (or the winter solstice here, here, here, here, here, here and here).
Or you can celebrate by checking out the gallery below of some of my favorite pictures of the Sun. If it's cloudy where you are, or you're in the southern hemisphere where it's the winter solstice today, then maybe that'll help spill a little golden glow into your day.
And finally, think on this: the Earth has had well over 4.5 billion summer solstices since it formed. And it'll have billions more! Just a little perspective to your day, care of the Universe.
Use the thumbnails and arrows to browse, and click on the images to go through to blog posts with more details and descriptions.