Search results
Results from the WOW.Com Content Network
The cosmic distance ladder (also known as the extragalactic distance scale) is the succession of methods by which astronomers determine the distances to celestial objects. A direct distance measurement of an astronomical object is possible only for those objects that are "close enough" (within about a thousand parsecs) to Earth.
Hubble's law, also known as the Hubble–Lemaître law, [ 1 ] is the observation in physical cosmology that galaxies are moving away from Earth at speeds proportional to their distance. In other words, the farther they are, the faster they are moving away. For this purpose, the recessional velocity of a galaxy is typically determined by ...
Star formation. Star formation is the process by which dense regions within molecular clouds in interstellar space, sometimes referred to as "stellar nurseries" or " star -forming regions", collapse and form stars. [1] As a branch of astronomy, star formation includes the study of the interstellar medium (ISM) and giant molecular clouds (GMC ...
The ratio between these quantities gives the Hubble rate, in accordance with Hubble's law. Typically, the distance is measured using a standard candle, which is an object or event for which the intrinsic brightness is known. The object's distance can then be inferred from the observed apparent brightness. Meanwhile, the recession speed is ...
a is the distance between the two stellar centers, and; m 1 and m 2 are the masses of the two stars. If a is taken to be the semimajor axis of the orbit of one body around the other, then r 1 is the semimajor axis of the first body's orbit around the center of mass or barycenter, and r 2 = a − r 1 is the semimajor axis of the second body's ...
Stellar parallax is the basis for the parsec, which is the distance from the Sun to an astronomical object that has a parallax angle of one arcsecond. (1 AU and 1 parsec are not to scale, 1 parsec = ~206265 AU) Stellar parallax is the apparent shift of position (parallax) of any nearby star (or other object) against the background of distant ...
e. In standard cosmology, comoving distance and proper distance (or physical distance) are two closely related distance measures used by cosmologists to define distances between objects. Comoving distance factors out the expansion of the universe, giving a distance that does not change in time due to the expansion of space (though this may ...
where F is the gravitational force acting between two objects, m 1 and m 2 are the masses of the objects, r is the distance between the centers of their masses, and G is the gravitational constant. The first test of Newton's law of gravitation between masses in the laboratory was the Cavendish experiment conducted by the British scientist Henry ...