Hydrostatic equilibrium happens when the pull of gravity is balanced by a pressure gradient which creates a pressure-gradient force in the other direction. The balance of these two forces is known as the hydrostatic balance. It flattens the surface of undisturbed liquids.
Right ascension
Right ascension (abbreviated RA; symbol α) is the astronomical word for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. It is the celestial counterpart to longitude. The other coordinate is the declination.
The moon, planets and stars all have their own right ascension. Many of them are listed in an almanac. Using arithmetic, the object’s right ascension and declination indicate where to look in the sky to see the object.
Declination
Declination (abbrev. dec or δ) is a word used in astronomy to describe one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. Dec is comparable to latitude, projected onto the celestial sphere, and is measured in degrees north and south of the celestial equator.
Retrograde and direct motion
Direct motion is the motion of a planetary body in a direction similar to that of other bodies within its system, and is sometimes called prograde motion. Retrograde motion is motion in the opposite direction. In the case of celestial bodies such as the retrograde Carme group of moons, such motion may be real, defined by the natural rotation or orbit of the body.
Every so often a planet seems to change direction and go the other way for a short period of time (in relation to the fixed stars), making a "retrograde loop" or squiggle in its track before carrying on as normal. This apparent retrograde motion, however, is seen because the Earth is moving. It is only seen when outer planets are near opposition.
A common analogy for the principle of apparent retrograde motion is that of turning on a circle. If two cars are travelling at the same constant speed from the same point on concentric circles "next to each other" such that one car is on the "outside" and the other on the "inside", then the car on the inside will complete its circle before the car on the outside, because it has a shorter distance to travel. Thus, it will seem to the driver of the car on the inside, that, although the speed of the cars is the same, the car on the outside is slower. The outside car will appear to "fall behind" the inside car. The same concept is the basis of retrograde motion.
Planetesimal
Planetesimals are small, solid objects thought to exist in protoplanetary disks around a young or forming star. Planetesimals are created when dust particles collide.
Achondrite
An achondrite is a stony meteorite that is made of material similar to terrestrial basalts or plutonic rocks. Compared to the chondrites, they have all been differentiated and reprocessed to a lesser or greater degree from the effects to melting and recrystallization on or within meteorite parent bodies.
Basalt
Basalt is a common grey to black rock. It is pushed out (extruded) by volcanos. The lava is rich in magnesium and iron. It has olivine and pyroxene minerals which make it dark in colour. Basalt is usually fine-grained because the lava cools rapidly on the Earth's surface. Flood basalts are commonplace, formed by lava pouring out and solidifying.
On Earth, most basalt magmas have formed by the hot molten mantle. Basalt has also formed on Earth's Moon, Mars, Venus, and even on the asteroid Vesta.
The crustal portions of oceanic tectonic plates are made mostly of basalt, produced from upwelling mantle below mid-ocean ridges.
Unweathered basalt is black or grey. Basalt blocks are often used for roads and pavements (sidewalks), and for houses and other buildings. It is hard-wearing and heat resistant.
Basalt can be made into fibre. Basalt fibre is often used as a safe replacement for asbestos. Intense heat and pressure can change basalt into its metamorphic rock equivalent. The rocks known as greenstone are basalt which has been metamorphised.
Aswan
Aswan (, population 200,000) is a city in the south of Egypt and the capital of the Aswan Governorate. It is on the east bank of the Nile and is a busy market and tourist center.
Aswan is one of the driest places in the world where people actually live; as of early 2001, the last rain there was 6 years earlier. As of October 13, 2007, the last rainfall was a thunderstorm on May 13, 2006. In Nubian settlements, the people often do not put a roof over all of the rooms in their houses.
Carl Barks
Carl Barks (March 27, 1901 - August 25, 2000) was a famous cartoonist. He was the inventor of Scrooge McDuck, the Beagle Boys, Gyro Gearloose and many other Walt Disney characters. He was often called the most important artist in Disney comics.
Carl Barks was born on March 27, 1901, near Merrill, Oregon, as part of a farming family. At the age of 10, he became interested in art for the first time. When he was 15, his mother died, and he began to help his father on the family's farm. In 1935, he took a contract with Disney and started as one of the studio's artists. Some months later, he become a part of Ted Sears "Story Department" at the Disney studios, where he wrote more than two dozen stories for short films with Donald Duck and other characters until 1942.
In 1942 he went to "Western Publishing". There he started drawing comics with Donald Duck and later with other characters - most of them he created by himself. He held this job until 1966, when he retired.
By the early 1990s, Carl Barks had become a comic legend. In 1994, at the age of 93, for the first time in his long life, he traveled to Europe and visited around a dozen countries. Some months earlier, his third wife, Margaret, called Garé, had died at the age of 75.
In 1999, leukemia began to destroy Barks' body. The "Duck Man" died, aged 99, on August 25, 2000, at his home in Grants Pass, Oregon.
Jay-Z
Shawn Corey Carter (born December 4, 1969), better known by his stage name JAY-Z (formerly Jay-Z and Jay Z), is an American rapper and entrepreneur. Jay-Z is known for beginning his career as a rapper and branching out into a successful business career, ultimately becoming one of the most powerful names in modern entertainment.
He released his first album in 1996, which was met with critical and commercial success. Its followed was followed up with more albums, each gaining the artist more sales and recognition with each release. He co-founded the record label Roc-A-Fella Records in 1995. From 2004 to 2007, he was the CEO of Def Jam Recordings. In 2008, he founded the successful record label and artist management company Roc Nation. Jay-Z also co-owns the Brooklyn Nets NBA team.
He is one of the most financially successful hip-hop artists and businessmen in America. Jay-Z married singer Beyoncé in 2008. In June 2019, it was reported that Jay-Z had become the first billionaire rapper.
Jay-Z had a really rough adolescence. At the age of 11 his father left the family, so he was raised by his mother, Gloria Carter. Like he said in a lot of his autobiographical songs, Jay-Z was involved with a lot of drug deals and gun violence. Jay-Z went to Eli Whitney High School, in Brooklyn, where he met the well-known The Notorious B.I.G.