Space exploration is the use of astronomy and space technology to explore outer space. 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. Space exploration, like its classical form astronomy, is one of the main sources for space science.
Buzz Aldrin taking a core sample of the Moon during the Apollo 11 mission
Self-portrait of Curiosity rover on Mars's surface
V-2 Rocket in the Peenemünde Museum
Model of Vostok spacecraft
Outer space is the expanse beyond celestial bodies and their atmospheres. It contains ultra-low levels of particle densities, constituting a near-perfect vacuum of predominantly hydrogen and helium plasma, permeated by electromagnetic radiation, cosmic rays, neutrinos, magnetic fields and dust. The baseline temperature of outer space, as set by the background radiation from the Big Bang, is 2.7 kelvins.
The boundary between space and Earth, at an altitude of 100 km, roughly where the yellow line of airglow is visible.
The black background is outer space as seen from Earth's surface at night. The interplanetary dust cloud is illuminated and visible as zodiacal light, with its parts the false dawn, gegenschein and the rest of its band, which is visually crossed by the Milky Way
Because of the hazards of a vacuum, astronauts must wear a pressurized space suit while outside their spacecraft.
Conventional anti-satellite weapons such as the SM-3 missile remain legal under space law, even though they create hazardous space debris