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Zeno's paradoxes are a series of philosophical arguments presented by the ancient Greek philosopher Zeno of Elea (c. 490–430 BC), [ 1 ][ 2 ] primarily known through the works of Plato, Aristotle, and later commentators like Simplicius of Cilicia. [ 2 ] Zeno devised these paradoxes to support his teacher Parmenides 's philosophy of monism ...
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.
In their rest frame the distance between the Earth and the star system is α d = 0.6 × 4 = 2.4 light years (length contraction), for both the outward and return journeys. Each half of the journey takes α d / v = 2.4 / 0.8 = 3 years, and the round trip takes twice as long (6 years). Their calculations show that they will arrive home having ...
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 ...
The percentage columns show the distance from the orbit compared to the semimajor axis. E.g. for the Moon, L 1 is 326 400 km from Earth's center, which is 84.9% of the Earth–Moon distance or 15.1% "in front of" (Earthwards from) the Moon; L 2 is located 448 900 km from Earth's center, which is 116.8% of the Earth–Moon distance or 16.8% ...
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 ...
Any two opposite edges of a tetrahedron lie on two skew lines, and the distance between the edges is defined as the distance between the two skew lines. Let d {\displaystyle d} be the distance between the skew lines formed by opposite edges a {\displaystyle a} and b − c {\displaystyle \mathbf {b} -\mathbf {c} } as calculated here .
t. e. In astronomy, Kepler's laws of planetary motion, published by Johannes Kepler absent the third law in 1609 and fully in 1619, describe the orbits of planets around the Sun. These laws replaced circular orbits and epicycles in the heliocentric theory of Nicolaus Copernicus with elliptical orbits and explained how planetary velocities vary.