Search results
Results from the WOW.Com Content Network
Astronomy (from the Greek ἀστρονομία from ἄστρον astron, "star" and -νομία -nomia from νόμος nomos, "law" or "culture") means "law of the stars" (or "culture of the stars" depending on the translation).
Size (left) and distance (right) of a few well-known galaxies put to scale. There are an estimated 100 billion galaxies in all of the observable universe. [1] On the order of 100,000 galaxies make up the Local Supercluster, and about 51 galaxies are in the Local Group (see list of nearest galaxies for a complete list).
The observable universe is a spherical region of the universe consisting of all matter that can be observed from Earth; the electromagnetic radiation from these objects has had time to reach the Solar System and Earth since the beginning of the cosmological expansion.
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.
Euler diagram showing the IAU Executive Committee conception of the types of bodies in the Solar System.. The International Astronomical Union (IAU) defined in August 2006 that, in the Solar System, [1] a planet is a celestial body that:
The Big Bang theory, which explains the Evolution of the Universe from a hot and dense state, is widely accepted by physicists.. In astronomy, cosmogony is the study of the origin of particular astrophysical objects or systems, and is most commonly used in reference to the origin of the universe, the Solar System, or the Earth–Moon system.
The state of matter refers to the distinct forms that different phases of matter take on.
This is a list of well-known online encyclopedias that are accessible or formerly accessible on the Internet.. The largest online encyclopedias are general reference works, though there are also many specialized ones.