Search results
Results from the WOW.Com Content Network
Interplanetary space within the Solar System is the space dominated by the gravitation of the Sun, outside the gravitational spheres of influence of the planets. [126] Interplanetary space extends well beyond the orbit of the outermost planet Neptune , all the way out to where the influence of the galactic environment starts to dominate over ...
The physical universe is defined as all of space and time [a] (collectively referred to as spacetime) and their contents. [10] Such contents comprise all of energy in its various forms, including electromagnetic radiation and matter, and therefore planets, moons, stars, galaxies, and the contents of intergalactic space.
Cosmic dust – also called extraterrestrial dust, space dust, or star dust – is dust that occurs in outer space or has fallen onto Earth. [ 1 ] [ 2 ] Most cosmic dust particles measure between a few molecules and 0.1 mm (100 μm ), such as micrometeoroids (<30 μm) and meteoroids (>30 μm). [ 3 ]
A planet or moon's interior heat is produced from the collisions that created the body, by the decay of radioactive materials (e.g. uranium, thorium, and 26 Al), or tidal heating caused by interactions with other bodies. Some planets and moons accumulate enough heat to drive geologic processes such as volcanism and tectonics.
Space exploration is the use of astronomy and space technology to explore outer space. [1] While the exploration of space is currently carried out mainly by astronomers with telescopes, its physical exploration is conducted both by uncrewed robotic space probes and human spaceflight.
In this map of the Observable Universe, objects appear enlarged to show their shape. From left to right celestial bodies are arranged according to their proximity to the Earth. This horizontal (distance to Earth) scale is logarithmic.
The space between galaxies is filled with a tenuous gas (the intergalactic medium) with an average density of less than one atom per cubic metre. Most galaxies are gravitationally organised into groups, clusters and superclusters. The Milky Way is part of the Local Group, which it dominates along with the Andromeda Galaxy.
Physical cosmology – the study of the largest-scale structures and dynamics of the universe and is concerned with fundamental questions about its formation and evolution. Planetary science – the scientific study of planets (including Earth), moons, and planetary systems, in particular those of the Solar System and the processes that form them.