Nature Reference Libraries

Page 4 of about 37 Articles
2005-05-26 08:39:06

In geology, the mineral monazite is a reddish-brown phosphate containing rare earth metals and an important source of thorium, lanthanum, and cerium. It occurs usually in small isolated crystals. There are actually three different kinds of monazite, depending on relative elemental composition of the mineral: - monazite-Ce (Ce, La, Nd, Th, Y)PO4 - monazite-La (La, Ce, Nd)PO4 - monazite-Nd...

2005-05-26 08:36:17

Murdochite is a mineral combining lead and copper oxides. It was first discovered in 1953 in Arizona.

Ring Current
2004-10-19 04:45:44

Ring Current -- A ring current is an electric current carried by charged particles trapped in a planet's magnetosphere. It is caused by the longitudinal drift of energetic (10-200 keV) particles. Earth's Ring Current Earth's ring current is responsible for geomagnetic storms. The ring current system consists of a band, at a distance of 3-5 RE(1), which lies in the equatorial plane and...

White Dwarf
2004-10-19 04:45:43

White Dwarf -- A white dwarf is a a star supported by electron degeneracy. A star like our Sun will become a white dwarf when it has exhausted its nuclear fuel. Near the end of its nuclear burning stage, such a star goes through a red giant phase and then expels most of its outer material (creating a planetary nebula) until only the hot (T > 100,000 K) core remains, which then settles...

Supernova Remnant
2004-10-19 04:45:42

Supernova Remnant -- A supernova remnant (SNR) is made up of the materials left behind by the gigantic explosion of a star in a supernova. There are two possible routes to this end: either a massive star may cease to generate fusion energy in its core, and collapse inward under the force of its own gravity, or a white dwarf star may accumulate material from a companion star until it reaches...

2004-10-19 04:45:42

Supernova -- A supernova is a star that increases its brightness drastically within a matter of days, making it appear as if a "new" star was born (hence "nova"). The "super" prefix distinguishes it from a mere nova, which also involves a star increasing in brightness, though to a lesser extent and through a much different mechanism. Astronomers have classified supernovae in several...

2004-10-19 04:45:41

Aurora -- The Polar Aurora are natural displays of light in the sky that can be seen with the unaided eye only at night. An auroral display in the Northern Hemisphere is called the aurora borealis, or the northern lights; in the Southern Hemisphere it is called the aurora australis. Auroras are the most visible effect of the sun's activity on the earth's atmosphere. The beautiful and often...

Word of the Day
  • A volcanic mudflow.
The word 'lahar' comes from Javanese.