Some 52 star systems beyond our own, the Solar System, lie within of the Sun. These systems contain 63 stars. 50 of these are red dwarfs, by far the most common type of star in the Milky Way. Much more massive stars, such as our own, make up the remaining 13. In addition to these "true" stars, scientists have identified 11 brown dwarfs (objects not quite massive enough to fuse hydrogen), and four white dwarfs. White dwarfs are extremely dense collapsed cores that remain after stars such as our Sun have exhausted all fusible hydrogen in their core and have slowly shed their outer layers. Despite the relative proximity of these 78 objects to Earth, only nine are bright enough in visible light to be visible to the naked eye from Earth, 6.5 apparent magnitude. All of these objects are currently moving in the Local Bubble, a region within the Orion–Cygnus Arm of the Milky Way.
List of planets
This is a list of two types of planets: standard planets and dwarf planets, in the Solar System.
"See List of exoplanets"
Technically, there was never a scientific definition of the term "planet" before 2006. When the Greeks observed the sky thousands of years ago, they discovered objects that acted differently than stars. These points of light seemed to wander around the sky throughout the year. The term "planet" is derived from the Greek word "planetes" - meaning wanderer.
in 2006 the International Astronomical Union (IAU) convened a Planet Definition Committee, deliberated, and ultimately reached consensus on a new definition of planet which leaves us with the eight planets we today consider to comprise the Solar System (thus the exit of Pluto). That new definition: " A “planet” is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit [meaning: 'there are no other bodies in its path that it must sweep up as it goes around the Sun'.]"
List of galaxies
List of galaxies and galaxy clusters. Because there are so many galaxies in the universe, this list has been divided into several categories.
The first catalog that catalogues galaxies is the Catalogue of Galaxies and of Clusters of Galaxies.
This is list of nearby galaxies to the Milky Way Galaxy, our galaxy. The first four listed below are part of the Local Group of galaxies, a galaxy group containing at least 50 galaxies, including the Milky Way and Andromeda.
This is list of farthest galaxy from Milky Way. Remember, the farther away from a galaxy, the greater the redshift of galaxy. Redshift is when object appear in a red color because the distance is farther away.
Note that the idea that the radius of the observable universe must amount to only 13.8 billion light-years (like the age of universe) is incorrect. Light travel distance (LTD) is time required for light to reach the observer.
(≈) means "almost equal to."
And other galaxies :
List of nearest galaxies
This list of the nearest galaxies to Earth is ordered by increasing distance. Many of the distances are only estimates, and some may be incorrect by 50% or more. The distance ranking in this list should be seen only as a guess. Distances are given in light years (ly).
List of satellites of the Milky Way
List of satellites of Milky Way:
"Note: ly means light years"
List of comets
This is a list of some comets in the solar system.
Periodic comets visit us again and again. Non-periodic comets visit us only once. On this list there is a "P" in front of the periodic comets. In front of non-periodic comets there is a "C". There is sometimes a number in front of the "P": it shows the number of times people saw the periodic comet visiting us.
Periodic comets have a special place in astronomy, because their orbits are often the same. We know when they will visit us, and we can plan to watch them, and send space probes to look at them.
On August 24, 1994, the International Astronomical Union (IAU) standardized the way they name this type of comet. This system tells us which comet is which. The IAU chose the letter P for periodic comets and D for periodic comets that were lost or which broke into pieces.
Other letters are C for "non-periodic" comets, and X for comets where we do not know their orbits. It uses A for objects people say are asteroids. Each name starts with a number, so two comets have the same name.
List of stars with confirmed extrasolar planets
The following is a list of main sequence stars with confirmed extrasolar planets. Note that the masses of the planets are lower bounds only. If a planet is detected by the spectral line displacement method referred to above, no information is gained about the inclination of the planet's plane of orbit around its star, and a value for this is needed to calculate the mass. It has become customary to arbitrarily assume that the plane is exactly lined up with the line of sight from Earth (this produces the lowest possible mass consistent with the spectral line measurements).
List of water sports
Many sports are played in water.
The following is a list of water sports, divided by category. This list is not complete. Some of the sports include only one part related to swimming, as for example Triathlon.
List of waterways
The list of waterways is a link page for any river, canal, estuary, or firth.
List of wave topics
This is a list of wave topics, by Wikipedia page.
List of waterfalls
This is a list of waterfalls.
List of tunnels
The list of tunnels is a link page for any road tunnel, railway tunnel, or waterway tunnel anywhere in the world.
List of tallest structures in the world
This is a list of tallest structures in the world, past and present of any type. Most of the structures are television broadcasting masts. There are also the taller tower-type structures (like the CN Tower) and the taller high rise buildings (like the Sears Tower).
The list also includes some other structures like oil platforms, electrical towers, bridge towers, etc. List is organized by absolute height since it includes many different classes of structures.
This list includes quite a few masts. A mast is a man-made support structure, commonly used on sailing ships as support for sails, or on land as radio masts and towers used to support telecommunication equipment such as radio antennas ("aerials" in the UK).
There is often ambiguity between the terms "tower" and "mast". A tower is a self-supporting or cantilevered structure, while a mast is held up by stays or guys. Both towers and masts have limited floor space and are non-building structures, as opposed to regular buildings which have greater floor space for occupancy. The terminology is further confused through misuse. Skyscrapers are often referred to as "towers" and some towers use the term "mast". Ironically, "skyscraper" has some etymology from references to high sailboat masts.
For practical purposes to keep the list to a reasonable length this part of list contains only notable structures.
This is an "incomplete" list of structures taller tha|N|1,148 feet (350 m) under construction. Please correct (by adding further one or by putting completed structures in the upper table, if current height is over 1,148 feet (350 m)).
The following table is a list of the current tallest structures by each continent thus sea oil platforms are not included (listed by geographic size):
The following table is a list of the all time tallest structures by each continent thus sea oil platforms are not included (listed by geographic size):
List of symbols
This is a list of graphical signs, icons, and symbols.
List of supermarkets
This is a list of supermarkets around the world.
see also, "List of Greek supermarkets"
"For full list, see Supermarkets in the United Kingdom"
"For full list, see Supermarkets in the United States"
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