Astronomy consists of the study of celestial bodies as well as the phenomenon which occurs throughout space which (outside the Earth’s atmosphere). One of the core questions asked by astronomers is how was the universe formed? The favored tool of an astronomer is the telescope which comes in a variety of forms in order to view close and far celestial objects.
The scientific field of astronomy is intertwined like most branches of science. Close correlations are made in particular with the fields of geology and physics. The analysis of physics on Earth and in space appears to be very different upon first glance. One major reason this occurs is because gravity varies greatly in different parts of the universe which can cause dramatic observational differences to a scientist. The specialty of astronomy which analyzes these variations is referred to as astrophysics.
When observing celestial bodies it is important to employ a taxonomic structure to allow better analysis. As such celestials bodies are classified individually and systems are recognized and classified as well. When referring to astronomy, the orbit route of celestial bodies is one of the primary focus of taxonomic classifications set forth by astronomers.
The universe describes all known portions of the world and space as currently theorized and witnessed by humans. Our universe is vastly immense and we have only begun to generate the technology necessary to observe celestial activity far from our planet. At this time much is not known on how our universe came into existence, operates or if it is a singular entity or plural.
A galaxy is gravitationally bound system of stars which appear to orbit a super massive black hole. Recent discoveries in astronomy and physics have been able to determine that every galaxy appears to have a super massive black hole in its center the orbit routes of solar systems within galaxies has been analyzed to support this theory. The gravitational forces set forth by the super massive black hole and by dark energy or dark matter appears to create the gravitational forces which unite a galaxy.
A solar system typically consists of one star and a multitude of planets which orbit it. The gravitational force of the star keeps the planets in orbit. In turn the solar system orbits a super massive black hole with in the galaxy. Solar systems are vastly diverse and vary most dramatically based on the star at the center of them. Depending on the type of star and its size, the gravitational fields of the solar system varies which can allow more planets, larger planets, and in some cases dual stars at the center of the solar system.
Planets as well can contain satellites which orbit them in the form of moons. The moons are bound to the planetary orbit by the gravity set forth by the parent planet. A moon is considered to be a dead celestial body, meaning that it does not have the geological life cycles that planets contain and they do not orbit a sun, instead they orbit a planet.
A star is a celestial body which is made up of the fourth state of matter, plasma. This plasma is held together by the gravitational forces of the density of the star. The stars were highly regarded in many religious ideologies and were believed to be the domain of the gods. As such many of the brightest stars in the sky received proper names and star clusters, or constellations, were named based on their general appearances. Stars shine through a process of thermonuclear fusion which involves the burning of helium and hydrogen. This produces solar radiation which is emitted throughout space and can be seen in many places throughout the universe.
A planet is a celestial body which orbits either a star or a remnant of a star, named from the Greek word for “wandering star”. A plant’s gravity must be less that that which would result in thermonuclear fusion (star) but great enough to cause the planet to have rounded its self from its own gravitational forces. In many ancient religions the planets were believed to be gods and which is how our solar system’s planets got their names during the Roman empire.
An asteroid is considered to be a small Solar System body and differs from a comet because it does not share the atmospheric characteristics and icy nature that a comet consists of. An asteroid is generally considered to be a planetoid or minor planet, meaning that it does orbit the sun but does not meet the gravitational mass of a planet (creating the rounded shape) or the characteristics of a comet. Asteroids will typically consist of rocks or metals and can be found in most solar systems.
A comet is considered to be a small Solar System body which is made up largely of ice and is in orbit of a star. When a comet’s orbit nears a star it is characterized by a thin visible atmosphere and often a tail which is made up of ice particles breaking off of the comet. These visible characteristics are caused by solar wind and solar radiation on the comet’s nucleus. The size of a comet can vary greatly and is made up generally of rock, dust particles and ice.
A meteor, or correctly called a meteoroid is essentially debris in space which does not follow a set orbit or navigation method. When a meteoroid enters the Earth’s atmosphere it creates a visible trail which consists of rock and metal particles breaking up in the atmosphere. This visible trail is referred to as a meteor or shooting star. If a meteor strikes the a planet and does not fully break up in its descent from the atmosphere this is generally referred to as a meteorite while a succession of meteors entering the atmosphere in close proximity is referred to as a meteor shower.
Solar winds are created when particles charged from the upper atmosphere of the sun are released in a stream out into space. This stream of charged particles is typically made up of electrons and photons and typically contains a high level of solar radiation. The particles are pushed out of the sun’s atmosphere in part by the extreme temperature combined with the high kinetic energy of the particles in the upper atmosphere of a star. Solar winds from our sun make up what is called the heliosphere which is essentially a bubble of solar wind which encases our Solar System.
An exoplanet, sometimes referred to as extrasolar planet, is considered to be a planet which exists outside of our Solar System. Although it was largely believed that extrasolar planets existed for several centuries, this fact was not confirmed with evidence until 1992 by astronomers. Today there have been approximately 839 exoplanets which have been identified throughout the galaxy. Typically an exoplanet must be identified indirectly through a process of radial velocity measurements however a few of these have been witnessed and mapped using telescopes.
A star cluster, also referred to as star clouds, are a group of stars which are typically bound in close proximity by their gravitational forces. There are two distinct types of star clusters, the first are globular clusters which consist of ancient stars and typically result in hundreds to thousands of stars grouped together, while the second group are called open clusters which are relatively young stars that tend to form much smaller clusters, typically consisting of only a few hundred. Open clusters are generally temporary phenomenon and experience a dissipation of stars as they float through molecular clouds in the galaxy which disrupts their gravitational bond. Despite the severance of their gravitational bonds these stars will usually still move in approximately the same direction as the open cluster.