When astronomers study the rotation of distant galaxies, they immediately come up against a puzzle. The stars are held together by gravity, which prevents them being slung into intergalactic space as the galaxies rotate. Indeed, astronomers can calculate the amount of gravity based on the mass of the stars they can see. The puzzle is that the outermost parts of these galaxies are moving too quickly. There does not seem to be enough of this mass to stop these stars from flying away. The fact that ...read more
In ancient cultures, solar eclipses were seen as apocalyptic prophecies, omens of the displeasure of the gods, periodic celestial coincidences, or some mixture of all three. The events stopped wars, made temporary kings, and perhaps founded ancient cities.Solar eclipses may strike awe or even fear in people, especially those less versed in astronomy. After all, they can turn an ordinary bright, clear day into relative darkness as the moon slowly blocks the sun. In ancient times, people could hav ...read more
One-point-two kilograms per cubic meter. Why is this number significant? It’s the approximate average density, or mass per volume, of the air at sea level. As you might expect, this mass pales in comparison to that of water, which is roughly 800 times denser than the atmosphere above it. Despite this, air has enough heft to ensure that high-speed hurricane winds can lift whole houses clean off the ground. And when pushed through a jet engine, it can hold a 640-ton airplane aloft — no mean f ...read more
A good night’s sleep is becoming a rare treasure. According to the National Institutes of Health (NIH), about one in three adults in the United States doesn’t get enough sleep, and an estimated 50 to 70 million Americans have chronic sleep disorders.Many people struggling to get enough sleep turn to nutritional supplements for help. Common sleep supplements are melatonin, valerian, and the currently trending ashwagandha, a plant used in traditional Ayurvedic medicine, an ancient Indian syste ...read more
Equipped with the latest gear and a thirst for adventure, mountaineers embrace the perils that come with conquering the world’s highest peaks. Yet, even those who tread more cautiously at high altitude are not immune from the health hazards waiting in the thin air above.Altitude sickness, which most commonly refers to acute mountain sickness, presents a significant challenge to those traveling to and adventuring in high-altitude destinations. Its symptoms can range from mildly annoying to inca ...read more
Author Vishay SinghPosted on Categories Discover Magazine