Magnification of phosphate crystals (© Steve Gschmeissner/Getty Images)

【October 23 2013】When measuring microscopic objects, such as these phosphate crystals, chemists use moles, a unit of measurement that was derived using the Avogadro constant. The simplest expression of Avogadro's number is 6.02x10^23. In the early 1980s, an article in "The Science Teacher" suggested that from 6:02 a.m. to 6:02 p.m., October 23, we should celebrate Mole Day. You do the math. Happy Mole Day!Explore breathtaking Gallery from the HuluTrip homepage over the past 5 years..