In a total lunar eclipse, the moon passes through the Earth's shadow. As it does so, it takes on a reddish/golden hue due to the sunlight passing through the Earth's atmosphere. Before and after the total eclipse, the Earth's shadow can be seen covering parts of the moon. There will be four lunar eclipses (a tetrad) visible in the United States in 2014-2015, the first of which occurred on April 14-15. The first so-called "blood moon" lasted 3.5 hours and began, Orange County time, at about midnight.
Prior to the 20th century, there were no blood moons for more than 300 years. The other celestial event on April 14 was that Mars was the closest to the Earth since 2008. Thus the millions of stargazers across North America could view the Red Planet and blood moon at the same time. The next total lunar eclipse will occur on October 8, 2014.