Rare earth

Rare earth may refer to:

Rare earth element

A rare earth element (REE) or rare earth metal (REM), as defined by IUPAC, is one of a set of seventeen chemical elements in the periodic table, specifically the fifteen lanthanides, as well as scandium and yttrium. Scandium and yttrium are considered rare earth elements because they tend to occur in the same ore deposits as the lanthanides and exhibit similar chemical properties.

Despite their name, rare earth elements are – with the exception of the radioactive promethium – relatively plentiful in Earth's crust, with cerium being the 25th most abundant element at 68 parts per million, or as abundant as copper. They are not especially rare, but they tend to occur together in nature and are difficult to separate from one another. (The word "rare" is an archaic word for "difficult".) However, because of their geochemical properties, rare earth elements are typically dispersed and not often found concentrated as rare earth minerals in economically exploitable ore deposits. It was the very scarcity of these minerals (previously called "earths") that led to the term "rare earth". The first such mineral discovered was gadolinite, a mineral composed of cerium, yttrium, iron, silicon and other elements. This mineral was extracted from a mine in the village of Ytterby in Sweden; four of the rare earth elements bear names derived from this single location.

Rare Earth (book)

Rare Earth: Why Complex Life Is Uncommon in the Universe is a 2000 popular science book about xenobiology by Peter Ward, a geologist and paleontologist, and Donald E. Brownlee, an astronomer and astrobiologist, both faculty members at the University of Washington. The book is the origin of the term 'Rare Earth Hypothesis' which, like the book, asserts the concept that complex life is rare in the universe.

Synopsis

The book argues that the universe is fundamentally hostile to complex life and that while microbial life may be common in the universe, complex intelligent life (like the evolution of biological complexity from simple life on Earth) required an exceptionally unlikely set of circumstances, and therefore complex life is likely to be extremely rare. The book argues that among the essential criteria for life are a terrestrial planet with plate tectonics and oxygen, a large moon, magnetic field, a gas giant like Jupiter for protection and an orbit in the habitable zone of the right kind of star.

1 (number)

1 (one; /ˈwʌn/ or UK /ˈwɒn/, also called unit, unity, and (multiplicative) identity), is a number, a numeral, and the name of the glyph representing that number. It represents a single entity, the unit of counting or measurement. For example, a line segment of unit length is a line segment of length 1.

As a number

One, sometimes referred to as unity, is the integer before two and after zero. One is the first non-zero number in the natural numbers as well as the first odd number in the natural numbers.

Any number multiplied by one is that number, as one is the identity for multiplication. As a result, one is its own factorial, its own square, its own cube, and so on. One is also the result of the empty product, as any number multiplied by one is itself. It is also the only natural number that is neither composite nor prime with respect to division, but instead considered a unit.

As a digit

The glyph used today in the Western world to represent the number 1, a vertical line, often with a serif at the top and sometimes a short horizontal line at the bottom, traces its roots back to the Indians, who wrote 1 as a horizontal line, much like the Chinese character 一. The Gupta wrote it as a curved line, and the Nagari sometimes added a small circle on the left (rotated a quarter turn to the right, this 9-look-alike became the present day numeral 1 in the Gujarati and Punjabi scripts). The Nepali also rotated it to the right but kept the circle small. This eventually became the top serif in the modern numeral, but the occasional short horizontal line at the bottom probably originates from similarity with the Roman numeral I. In some countries, the little serif at the top is sometimes extended into a long upstroke, sometimes as long as the vertical line, which can lead to confusion with the glyph for seven in other countries. Where the 1 is written with a long upstroke, the number 7 has a horizontal stroke through the vertical line.

No.1 (Uverworld song)

No.1 is a Japanese-language song, and the seventeenth single, by the Japanese band Uverworld and was released on November 19, 2008. This song was also perform at Tokyo Dome as a leading track for Last Tour Final. Limited edition version contains Three live song footage at Zepp Tokyo from Last Tour 2010.

Track listing

CD

DVD

Personnel

One (disambiguation)

1 A.D. is a year.

1, one, or ONE may also refer to:

Geography

Companies