Rikunarita-ORG/Wikinium huggingface dataset:
# United States Air Force

The **United States Air Force** (**USAF**) is the aerial warfare branch of the United States Armed Forces and one of the eight uniformed services. It was part of the U.S. Army until September 18, 1947.

The Air Force is the largest air force in the world and considered one of the most technologically advanced. It has thousands of aircraft in service. including bombers, fighter aircraft, and transport, and hundreds of intercontinental ballistic missiles. Hundreds of thousands of men and women are on active duty in the Air Force and others are in the reserves and the United States National Guard.

## Officer ranks

| **Pay grade** | O-1 | O-2 | O-3 | O-4 | O-5 | O-6 | O-7 | O-8 | O-9 | O-10 | Special |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| **Insignia** |  |  |  |  |  |  |  |  |  |  |  |
| **Title** | Second Lieutenant | First Lieutenant | Captain | Major | Lieutenant Colonel | Colonel | Brigadier General | Major General | Lieutenant General | General | General of the Air Force |
| Abbreviation2 | 2d Lt | 1st Lt | Capt | Maj | Lt Col | Col | Brig Gen | Maj Gen | Lt Gen | Gen | GAF |
|  |
| NATO Code | OF-1 | OF-2 | OF-3 | OF-4 | OF-5 | OF-6 | OF-7 | OF-8 | OF-9 | OF-10 |
| 1 Awarded as an honorary rank or during periods of a declared war.
2 No periods are used in actual grade abbreviation. |

### Warrant officers

The Air Force warrant officer ranks, while authorized by law, are not used.

### Enlisted personnel

Pararescuemen and a simulated "survivor" watch as an HH-60G Pave Hawk helicopter comes in for a landing.

| **US DoD Pay grade** | E-1 | E-2 | E-3 | E-4 | E-5 | E-6 | E-7 | E-8 | E-9 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Insignia | *No Insignia* |  |  |  |  |  |  |  |  |  |  |  |  |  |
| Title | Airman Basic | Airman | Airman First Class | Senior Airman | Staff Sergeant | Technical Sergeant | Master Sergeant¹ | Senior Master Sergeant¹ | Chief Master Sergeant¹ | Command Chief Master Sergeant | Chief Master Sergeant of the Air Force |
| Abbreviation | AB | Amn | A1C | SrA | SSgt | TSgt | MSgt | SMSgt | CMSgt | CCM | CMSAF |
| NATO Code | OR-1 | OR-2 | OR-3 | OR-4 | OR-5 | OR-6 | OR-7 | OR-8 | OR-9 | OR-9 | OR-9 |
|
¹ The USAF does not have a separate First Sergeant rank; it is instead a duty denoted by a diamond within the upper field. |

## Other websites

* Find a grave memorial of a World War II "WASP" {Women Air Service pilot}
# Strontium

Granules of strontium in a glass tube
A piece of strontianite
**Strontium** is a chemical element. It has the chemical symbol **Sr**. It has the atomic number 38. It is a metal. The color of the metal is silver-white or yellow-silver. The metal is soft, and highly reactive chemically.

In chemistry it is placed in a group of metal elements named the alkaline earth metals. Strontium has a high chemical reactivity. The metal turns yellow when exposed to air. Strontium has properties similar to those of its two vertical neighbors in the periodic table, calcium and barium.

It is found naturally in the minerals celestite and strontianite. The 90Sr isotope is present in radioactive fallout and has a half-life of 28.9 years.

Strontium forms salts which make a red flame when they burn. They are used in flares for signalling the position of survivors or shipwrecks and to make the red color in fireworks.
It is named after the village of Strontian, Scotland.
# Neutron star

Radiation from the pulsar PSR B1509-58, a rapidly spinning neutron star, makes nearby gas glow in X-rays (gold, from Chandra) and illuminates the rest of the nebula, here seen in infrared (blue and red, from WISE)
A model that shows what a neutron star would look like on the inside section.
A **neutron star** is a very small and dense star made almost completely of neutrons. They are small stars with a radius of about 11–11.5 kilometres. They have a mass of about twice that of the Sun. They are the smallest and densest stars known to exist in the Universe. They are what is left of a huge star which exploded as a supernova.

The density of the star is like that of the nucleus of an atom. They have strong magnetic fields, between 108 and 1015 times as strong as that of Earth. The gravitational field at the neutron star's surface is about 2×1011 times stronger than on Earth.

To imagine how dense a neutron star is, take all of the mass of our sun (which has a diameter of 1,392,000 kilometres (865,000 mi)) and push it down into a size that would fit into a ball with a 19 kilometres (12 mi) diameter. Another way to understand the density is this: one teaspoon of matter from the neutron star would weigh 6 billion tons.

Neutron stars spin very fast, from 0.001 second up to 30 seconds to turn. They come in different types. They may emit beams of electromagnetic radiation as pulsars. Other types are magnetars and binary pulsars.

Neutron stars are very hot, usually around 600000 °C at their surface.

## History

In 1934, Walter Baade and Fritz Zwicky proposed the existence of neutron stars, only a year after the discovery of the neutron by James Chadwick.

Looking for the origin of a supernova, they suggested that in supernova explosions ordinary stars are turned into stars that consist of extremely closely packed neutrons, which they called neutron stars. Baade and Zwicky suggested that the release of the gravitational binding energy of the neutron stars powers the supernova: "In the supernova process, mass in bulk is annihilated".

Neutron stars were thought to be too faint to be detectable. Little work was done on them until November 1967, when Franco Pacini (1939–2012) pointed out that if the neutron stars were spinning and had large magnetic fields, then electromagnetic waves would be emitted. Radio astronomer Antony Hewish and his research assistant Jocelyn Bell at Cambridge soon detected radio pulses from stars that are now known as pulsars.
# Thales

| Thales of Miletus (Θαλής ο Μιλήσιος) |
| --- |
| Thales |
|  |
| School | Ionian Philosophy, Milesian school, Naturalism |
| Main interests | Ethics, Metaphysics, Mathematics, Astronomy |
| Notable ideas | Water is the physis, Thales' theorem |
|
Influenced
* Pythagoras, Anaximander, Anaximenes
 |
|  |

**Thales of Miletus**, about 624 BC – 546 BC, was a pre-Socratic Greek philosopher. He was from Miletus in Asia Minor. Many, notably Aristotle, regard him as the first philosopher in the Greek tradition.

According to Bertrand Russell, "Western philosophy begins with Thales". Thales attempted to explain natural phenomena without reference to mythology and was tremendously influential in this respect. Almost all of the other pre-Socratic philosophers follow him in attempting to provide an explanation of ultimate substance, change, and the existence of the world—without reference to mythology. Those philosophers were also influential, and eventually Thales' rejection of mythological explanations became an essential idea for science. He was also the first to define general principles and set forth hypotheses. As a result he has been called the "Father of Science", though maybe Democritus is more deserving of this title.

In mathematics, Thales used geometry to solve problems such as calculating the height of pyramids and the distance of ships from the shore. He is the first known individual to whom a mathematical discovery has been attributed. Also, Thales was the first person known to have studied electricity.

## Referencesty
# Constellation

Cancer constellation map
A **constellation** is a group of stars which make up imaginary outline or pattern in the night sky (the celestial sphere). Usually they are said to represent an animal, mythological person or creature in a shape. When seen, the group of stars seem to make a pattern.

The word constellation comes from Latin: *con-*, meaning together and *stella-* meaning stars. Some examples of constellations are Ursa major, Orion, Taurus, Draco, Cancer etc. Constellations were used to group stars. Different places in the world may have different constellations, but today astronomy has a fixed set of 88 constellations. This set is based on the Greek set and later some southern constellations were added, for example Antlia - the air pump. Most constellations have names that come from Greek mythology, like Orion or Andromeda.

There are 12 constellations in the Zodiac. The Sun travels through the Zodiac once each year. There is also a thirteenth constellation Ophiuchus - the carrier of a serpent, which the Sun goes through. However, most people do not think that it is in the Zodiac.

## History

* No one knows who first saw the constellations. Ancient civilizations, like the Mayans, drew their own star maps of the skies with their constellations, very few of which we use today.
* Ptolemy's 48 constellations are still recognized by the IAU today, and the rest of the constellations were added later