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What Is a Black Hole? A black hole is a place in space where gravity pulls so much that even light can not get out. The gravity is so strong because matter has been squeezed into a tiny space. This can happen when a star is dying.
A black hole is a region of spacetime from which gravity prevents anything, including light , from escaping. [ 1 ] The theory of general relativity predicts that a sufficiently compact mass will deform spacetime to form a black hole. Around a black hole there is a mathematically defined surface called an event horizon that marks the point of no return. It is called "black" because it absorbs all the light that hits the horizon, reflecting nothing, just like a perfect black body in thermodynamics . [ 2 ] [ 3 ] Quantum field theory in curved spacetime predicts that event horizons emit radiation like a black body with a finite temperature .
The Milky Way bar is a chocolate bar distributed by the Mars confectionery company . The American version of the Milky Way bar is made of chocolate- malt nougat topped with caramel and covered with milk chocolate and is very similar to the Mars bar sold in other countries. The non-US Milky Way bar, on the other hand, is not topped with caramel and is therefore similar to the American 3 Musketeers bar . [ edit ] American version The Milky Way bar was created in 1923 by Frank C.
The Milky Way is the galaxy that contains our Solar System . [ 11 ] [ 12 ] [ 13 ] [ nb 1 ] This name derives from its appearance as a dim "milky" glowing band arching across the night sky, in which the naked eye cannot distinguish individual stars. The term "Milky Way" is a translation of the Classical Latin via lactea , from the Hellenistic Greek γαλαξίας κύκλος (pr. galaxías kýklos , "milky circle"). [ 14 ] [ 15 ] [ 16 ] The Milky Way appears like a band because it is a disk-shaped structure being viewed from inside. The fact that this faint band of light is made up of stars was proven in 1610 when Galileo Galilei used his telescope to resolve it into individual stars. In the 1920s, observations by astronomer Edwin Hubble showed that the Milky Way is just one of many galaxies. The Milky Way is a barred spiral galaxy 100,000–120,000 light-years in diameter containing 200–400 billion stars .
Astronauts wear various types of clothing for all aspects of a mission to space. Whether preparing for launch, working inside the space shuttle or the space station, working outside in space, or landing back on Earth, astronauts wear the proper garments for both comfort and protection. Space Station Clothing
Atmospheric Re-entry The Kepler formula also applies to elliptical motion, provided R is replaced by the semi-major axis a of the orbit. Over time however orbits stray from exact Keplerian ellipses because to additional forces, such as the attraction of the Moon and the Sun.
Various earth orbits drawn to scale; the inner cyan (light blue) ring represents low Earth orbit (LEO). Roughly half an orbit of the ISS A low Earth orbit ( LEO ) is generally defined as an orbit below an altitude of approximately 2,000 kilometers (1,200 mi). Given the rapid orbital decay of objects below approximately 200 kilometers (120 mi), the commonly accepted definition for LEO is between 160 kilometers (99 mi) (with a period of about 88 minutes) and 2,000 kilometers (1,200 mi) (with a period of about 127 minutes) above the Earth's surface. [ 1 ] [ 2 ] With the exception of the lunar flights of the Apollo program , all human spaceflights have taken place in LEO (or were suborbital). The altitude record for a human spaceflight in LEO was Gemini 11 with an apogee of 1,374.1 kilometers (853.8 mi). All manned space stations to date, as well as the majority of artificial satellites , have been in LEO.
What an Orbit Really Is The drawings at the right simplify the physics of orbiting Earth. We see Earth with a huge, tall mountain rising from it. The mountain, as Isaac Newton first envisioned, has a cannon at the top. When the cannon is fired, the cannonball follows its ballistic arc, falling as a result of Earth's gravity, and it hits Earth some distance away from the mountain. If we put more gunpowder in the cannon, the next time it's fired, the cannonball goes halfway around the planet before it hits the ground.
Neil Alden Armstrong (August 5, 1930 – August 25, 2012) was an American astronaut and the first person to walk on the Moon . He was also an aerospace engineer , naval aviator , test pilot , and university professor . Before becoming an astronaut, Armstrong was an officer in the U.S.
Space is the boundless three-dimensional extent in which objects exist and events occur and have relative position and direction. [ 1 ] Physical space is often conceived in three linear dimensions , although modern physicists usually consider it, with time , to be part of a boundless four-dimensional continuum known as spacetime . In mathematics , "spaces" are examined with different numbers of dimensions and with different underlying structures. The concept of space is considered to be of fundamental importance to an understanding of the physical universe .