All Topics  
Recessional velocity

 

   Email Print
   Bookmark   Link






 

Recessional velocity



 
 
Recessional Velocity is a term used to describe the rate at which an object is moving away, typically from Earth
Earth

Earth is the third planet from the Sun. Earth is the largest of the terrestrial planets in the Solar System in diameter, mass and density. It is also referred to as the World and Wiktionary:Terra.Note that by International Astronomical Union convention, the term "Terra" is used for naming extensive land masses, rather...
.
term is generally only used in reference to distant Galaxies
Galaxy

A galaxy is a massive, gravitation system that consists of stars and stellar remnants, an interstellar medium of gas and cosmic dust, and an important but poorly-understood component tentatively dubbed dark matter....
. The most common reason for the use of this term is Hubble's Law, which states that the redshift
Redshift

In physics and astronomy, redshift occurs when electromagnetic radiation?usually visible light?emitted or reflected by an object is shifted towards the red end of the electromagnetic spectrum due to the Doppler effect....
 is proportional to the distance between an inertial observer
Observation

Observation is either an activity of a living being , consisting of receiving knowledge of the outside world through the senses, or the recording of data using scientific instruments....
 and a distant galaxy
Galaxy

A galaxy is a massive, gravitation system that consists of stars and stellar remnants, an interstellar medium of gas and cosmic dust, and an important but poorly-understood component tentatively dubbed dark matter....
. The redshift is usually interpreted as due to Recessional Velocity which can be calculated according to the formula:

where is the Hubble constant, is the intervening distance, and is the Recessional Velocity, generally measured in km/s.

The recessional velocity of a galaxy is usually calculated from the redshift
Redshift

In physics and astronomy, redshift occurs when electromagnetic radiation?usually visible light?emitted or reflected by an object is shifted towards the red end of the electromagnetic spectrum due to the Doppler effect....
 observed in its emitted electromagnetic radiation
Electromagnetic radiation

Electromagnetic radiation takes the form of wave propagation waves in a vacuum or in matter. EM radiation has an electric field and magnetic field component which oscillate in phase perpendicular to each other and to the direction of energy Wave propagation....
.






Discussion
Ask a question about 'Recessional velocity'
Start a new discussion about 'Recessional velocity'
Answer questions from other users
Full Discussion Forum



Encyclopedia


Recessional Velocity is a term used to describe the rate at which an object is moving away, typically from Earth
Earth

Earth is the third planet from the Sun. Earth is the largest of the terrestrial planets in the Solar System in diameter, mass and density. It is also referred to as the World and Wiktionary:Terra.Note that by International Astronomical Union convention, the term "Terra" is used for naming extensive land masses, rather...
.

Application to Cosmology

This term is generally only used in reference to distant Galaxies
Galaxy

A galaxy is a massive, gravitation system that consists of stars and stellar remnants, an interstellar medium of gas and cosmic dust, and an important but poorly-understood component tentatively dubbed dark matter....
. The most common reason for the use of this term is Hubble's Law, which states that the redshift
Redshift

In physics and astronomy, redshift occurs when electromagnetic radiation?usually visible light?emitted or reflected by an object is shifted towards the red end of the electromagnetic spectrum due to the Doppler effect....
 is proportional to the distance between an inertial observer
Observation

Observation is either an activity of a living being , consisting of receiving knowledge of the outside world through the senses, or the recording of data using scientific instruments....
 and a distant galaxy
Galaxy

A galaxy is a massive, gravitation system that consists of stars and stellar remnants, an interstellar medium of gas and cosmic dust, and an important but poorly-understood component tentatively dubbed dark matter....
. The redshift is usually interpreted as due to Recessional Velocity which can be calculated according to the formula:

where is the Hubble constant, is the intervening distance, and is the Recessional Velocity, generally measured in km/s.

The recessional velocity of a galaxy is usually calculated from the redshift
Redshift

In physics and astronomy, redshift occurs when electromagnetic radiation?usually visible light?emitted or reflected by an object is shifted towards the red end of the electromagnetic spectrum due to the Doppler effect....
 observed in its emitted electromagnetic radiation
Electromagnetic radiation

Electromagnetic radiation takes the form of wave propagation waves in a vacuum or in matter. EM radiation has an electric field and magnetic field component which oscillate in phase perpendicular to each other and to the direction of energy Wave propagation....
. The distance to the galaxy
Galaxy

A galaxy is a massive, gravitation system that consists of stars and stellar remnants, an interstellar medium of gas and cosmic dust, and an important but poorly-understood component tentatively dubbed dark matter....
 is then estimated using Hubble's Law
Hubble's law

Hubble's law is the statement in physical cosmology that distant galaxy are receding from us at a velocity Proportionality to their distance from us....
.