In 1992, Mae C. Jemison (born 1956) became the first African American woman to travel in space. Mae C. Jemison had received two undergraduate degrees and a medical degree, had served two years as a Peace Corps medical officer in West Afric...

fl. 1200s Venetian merchant and trader who made several extended trips into central Asia to the court of Kublai Khan. He made the first trip, 1253-1269, with his brother Niccoló; the second, 1271-1295, with Niccoló and Niccol...

Before the nineteenth century, few Americans read newspapers or magazines or engaged in public entertainment. By 1900, scheduled sporting, entertainment, and mass cultural events had become commonplace in the United States, and there was a...

Joining the Los Angeles Lakers of the National Basketball Association in 1979, Earvin "Magic" Johnson, Jr. (born 1959) became one of basketball's most popular stars. In November 1991, Magic Johnson stunned the sportsworld with his announce...

A magic square is an n x n grid in which numbers have been written in such a way that the sum of the numbers along any row, column, or main diagonal is always the same magic constant. In a pure magic square, the numbers in the grid must be...

A magma chamber is a reservoir of molten rock that is the source of lava in a volcanic eruption. Magma chambers are typically located a few kilometers below the surface. A magma chamber is created by a mantle plume, or upwelling of heat fr...

Magnesium Chloride Overview Magnesium chloride (mag-NEE-zee-um KLOR-ide) is a white crystalline solid that is strongly deliquescent. It absorbs moisture from the air to become the hydrated form, magnesium chloride hexahydrate (MgCl2·...

Magnesium Oxide Overview Magnesium oxide (mag-NEE-see-um OK-side) is available commercially in several forms, depending on the way it is prepared and the use for which it is intended. Most forms can be classified as either "light�...

Magnesium Sulfate Overview Magnesium sulfate (mag-NEE-zee-um SUL-fate) occurs as the anhydrous salt and in a number of hydrated forms, including MgSO4·H2O, MgSO4·4H2O, MgSO4·5H2O, MgSO4·6H2O, and MgSO4·7H2...

Sometime before the fourth century B.C. the Chinese noticed that certain minerals, properly prepared, always pointed to the south. The mineral was magnetite, commonly called lodestone, and it was made into what the Chinese called a ...

Earth acts as though it were a huge dipole magnet with the positive and negative poles near the North and South Poles. This does not mean that Earth is literally a dipole magnet—there are too many variations in the field—but ...

Fusion is a nuclear process in which two atoms are combined to create a different atom (and some by-products). Magnetic confinement fusion uses a magnetic field to compress and heat gases into the plasma state so that fusion can take place...

Any current circulating in a planar loop produces a magnetic moment whose magnitude is equal to the product of the current and the area of the loop. When any charged particle is rotating, it behaves like a current loop with a magnetic mome...

Magnetic resonance imaging (MRI) is the application of nuclear magnetic resonance to produce images. MRI is now a common, though relatively expensive, diagnostic technique. MRI images can be very detailed and informative and the technique ...

A magnetic stripe card is a card (e.g., a credit card) that contains a stripe of magnetically-encoded data. These cards are paired with readers and writers, and are used in a wide variety of applications for storing information. Most iden...

What is magnetism and how is it useful? In order to give a clear explanation, some background information must be known. The word magnetism comes from the ancient Greek name for certain naturally occurring iron oxide stones called loadsto...

A magnetometer measures the strength and direction of a magnetic field. The first magnetometers were mechanical devices that had a spring-loaded magnet which moved in relation to an external magnetic field. The greater the movement, the gr...

"They were seven—and they fought like seven hundred!" screamed the posters for this 1960 western film, which spawned a number of sequels and helped launch the careers of Steve McQueen, James Coburn, and Charles Bronson...

(2002 est. pop. 4.7 million). Magwe (Magway) Division, located in the central dry zone of Myanmar (Burma), has an area of 44,820 square kilometers. The town of Magwe, 530 kilometers from the national capital of Yangon (Rangoon), is its cap...

The term mahalla is used by Uzbeks. It originated in Arabic and translates as encampment, neighborhood, or community. The term guzar is often used in place of mahalla among the Tajiks living in Uzbekistan; the term avlod is used by Tajiks ...

(2002 est. pop. 98.6 million). Maharashtra, the third largest state of the Indian Union in terms of area and population, lies on the west coast of India facing the Arabian Sea. The state shares its boundary with Gujarat, Madhya Pradesh, An...

Despite a controversial career in politics, Datuk Seri Mahathir bin Mohamad (born 1925) became prime minister of Malaysia in 1981 and then won four consecutive elections. He is listed as the 41st oldest office-holders among the worldwide l...

Vardhamana Mahavira (599 BC-527 BC), called the Jina, was an Indian ascetic philosopher and the principal founder of Jainism--one of the major religions of the Indian subcontinent. Vardhamana Mahavira was born in northern India during the ...

The monumental Sanskrit poem the Mahabharata, attributed to the legendary poet-seer Krsna Dvaipayana Vyasa (fifth century? BCE), although perhaps not the oldest epic poem to have survived from antiquity, is certainly the longest and undoub...

Mahlon Hoagland is best known for discovering, in the 1950s, that ribonucleic acid ( RNA) molecules in the cytoplasm retrieve specific amino acids and take them to the ribosomes for assembly into proteins. Hoagland was born in Boston, the ...