Science

A huge bottled-water industry has recently emerged, with the U.S. its largest consumer. But is bottled water actually healthier, safer, or tastier than tap water? A water expert explains that bottled water does not meet the same strict standards in the U.S. as water from the tap, though tap-water quality can vary among communities.

Despite its wonders, Earth's water cycle does not spread water evenly around the planet. The Ogallala Aquifer’s huge underground reservoir of water gives the relatively dry Central Plains states such as Nebraska a large but limited irrigation source. But the aquifer's water is being used up faster than it is beng replenished.

This awe-inspiring video shows of the process of human reproduction from conception to birth. It explains how mitosis and meiosis create genetic variation, how the ovum travels from the ovary to the uterus, how sperm pass the cervix, how one sperm achieves fertilization with the ovum, how the zygote begins cell differentiation, and how the embryo grows into a fetus ready for birth.