From Wikipedia, the free encyclopedia
The Outer space Portal

Introduction

The lower half shows a blue planet with patchy white clouds. The upper half has a man in a white spacesuit and maneuvering unit against a black background.
Because of the hazards of a vacuum, astronauts must wear a pressurized space suit while off-Earth and outside their spacecraft.
Illustration of Earth's atmosphere gradual transition into outer space

Outer space (or simply space) is the expanse beyond celestial bodies and their atmospheres. Outer space is not completely empty; it is a near-perfect vacuum containing a low density of particles, predominantly a plasma of hydrogen and helium as well as electromagnetic radiation, magnetic fields, neutrinos, dust, and cosmic rays. The baseline temperature of outer space, as set by the background radiation from the Big Bang, is 2.7 kelvins (−270 °C; −455 °F).

The plasma between galaxies is thought to account for about half of the baryonic (ordinary) matter in the universe, having a number density of less than one hydrogen atom per cubic metre and a kinetic temperature of millions of kelvins. Local concentrations of matter have condensed into stars and galaxies. Intergalactic space takes up most of the volume of the universe, but even galaxies and star systems consist almost entirely of empty space. Most of the remaining mass-energy in the observable universe is made up of an unknown form, dubbed dark matter and dark energy.

Outer space does not begin at a definite altitude above Earth's surface. The Kármán line, an altitude of 100 km (62 mi) above sea level, is conventionally used as the start of outer space in space treaties and for aerospace records keeping. Certain portions of the upper stratosphere and the mesosphere are sometimes referred to as "near space". The framework for international space law was established by the Outer Space Treaty, which entered into force on 10 October 1967. This treaty precludes any claims of national sovereignty and permits all states to freely explore outer space. Despite the drafting of UN resolutions for the peaceful uses of outer space, anti-satellite weapons have been tested in Earth orbit.

Humans began the physical exploration of space during the 20th century with the advent of high-altitude balloon flights. This was followed by crewed rocket flights and, then, crewed Earth orbit, first achieved by Yuri Gagarin of the Soviet Union in 1961. The economic cost of putting objects, including humans, into space is very high, limiting human spaceflight to low Earth orbit and the Moon. On the other hand, uncrewed spacecraft have reached all of the known planets in the Solar System. Outer space represents a challenging environment for human exploration because of the hazards of vacuum and radiation. Microgravity has a negative effect on human physiology that causes both muscle atrophy and bone loss. ( Full article...)

Selected article

Jupiter, as seen from Voyager (1979)

Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is two and a half times as massive as all of the other planets in our Solar System combined. Jupiter, along with Saturn, Uranus, and Neptune, is classified as a gas giant. When viewed from Earth, Jupiter can reach an apparent magnitude of -2.8, making it the fourth brightest object in the night sky. The planet was known by astronomers of ancient times and was associated with the mythology and religious beliefs of many cultures. Jupiter is primarily composed of hydrogen with only a small proportion of helium; it may also have a rocky core of heavier elements. The outer atmosphere is visibly segregated into several bands at different latitudes, resulting in turbulence and storms along their interacting boundaries. A prominent result is the Great Red Spot, a giant storm that is known to have existed since at least the seventeenth century. Surrounding the planet is a faint planetary ring system and a powerful magnetosphere. There are also at least 67 moons, including the four large moons called the Galilean moons that were first discovered by Galileo Galilei in 1610. Jupiter has been explored on several occasions by robotic spacecraft, most notably during the early Pioneer and Voyager fly-by missions and later by the Galileo orbiter.

Selected picture

Space-related portals

General images

The following are images from various outer space-related articles on Wikipedia.

Did you know (auto-generated)

Space news

Upcoming spaceflight launches

Astronomical events

Topics

By year

Categories

Category puzzle
Category puzzle
Select [►] to view subcategories

Wikimedia

The following Wikimedia Foundation sister projects provide more on this subject:

Discover Wikipedia using portals