Of the four fundamental interactions, gravitation is the dominant at astronomical length scales. Gravity effects are cumulative; by contrast, the effects of positive and negative charges tend to cancel one another, making electromagnetism relatively insignificant on astronomical length scales. The remaining two interactions, the weak...

By astronomical convention, the four seasons can be determined by the solstices—the points in the orbit of maximum axial tilt toward or away from the Sun—and the equinoxes, when Earth rotational axis is aligned with its orbital axis. In the Northern Hemisphere, winter solstice currently...

Cream skimmed from milk may be called "sweet cream" to distinguish it from cream skimmed from whey, a by-product of cheese-making. Whey cream has a lower fat content and tastes more salty, tangy and "cheesy". In many countries, cream is usually sold partially fermented: sour...

There are a number of different theories and hypotheses regarding early state formation that seek generalizations to explain why the state developed in some places but not others. Other scholars believe that generalizations are unhelpful and that each case of early state formation should be...

During the late 16th century it became fashionable for young European aristocrats and wealthy upper-class men to travel to significant European cities as part of their education in the arts and literature. This was known as the Grand Tour, it included cities such as London,...