In 1912 Vesto Slipher measured the first Doppler shift of a " spiral nebula " ( spiral nebula is the obsolete term for spiral galaxies ), and soon discovered that almost all such nebulae were receding from Earth.

File: Cdoppler. jpg | Christian Doppler ( 1803-1853 ): first described how the observed frequency of light and sound waves is affected by the relative motion of the source and the detector, a phenomenon which became known as the Doppler effect.

The effect is named after Christian Doppler, who offered the first known physical explanation for the phenomenon in 1842.

The first Doppler redshift was described by French physicist Hippolyte Fizeau in 1848, who pointed to the shift in spectral lines seen in stars as being due to the Doppler effect.

Some later V-2s used " guide beams ", radio signals transmitted from the ground, to keep the missile on course, but the first models used a simple analog computer that adjusted the azimuth for the rocket, and the flying distance was controlled by the timing of the engine cut-off, " Brennschluss ", ground controlled by a Doppler system or by different types of on-board integrating accelerometers.

* Doppler Imaging: Results first Doppler image of a Pleiades solar-type G dwarf – HII314, Strassmeier & Rice 2001, A & A 377, 264

The Doppler measurements of the Venera 4 to 7 probes were the first evidence of the existence of high-speed zonal winds ( up to or 225mph ) in the Venus atmosphere ( super rotation ).

The first example of laser cooling, and also still the most common method of laser cooling ( so much so that it is still often referred to simply as ' laser cooling ') is Doppler cooling.

* Ring-diagram analysis, first introduced by F. Hill, is used to infer the speed and direction of horizontal flows below the solar surface by observing the Doppler shifts of ambient acoustic waves from power spectra of solar oscillations computed over patches of the solar surface ( typically 15 ° × 15 °).

In early experiments, such as the first radar detection of Ceres, radar observations of asteroids were restricted to measurements of Doppler shifts and radar cross-sections.

By obtaining periodic Doppler shifts in the components of Algol, Vogel proved that the latter was a binary star ; thus, Algol was one of the first known spectroscopic binaries ( and it is also known to be an eclipsing binary ).

The Doppler Gravity Experiment ( DGE ) was the first polar, low-altitude mapping of the lunar gravity field.

WTSP also acquired Tampa Bay's first Doppler weather radar called " StormSeeker " in 1980 and was one of the first television stations in the country to use a computer in weather forecasting called " WeatherEye " ( 1979 ) and was the first station in the market with a 7-day forecast ( 1992 ).

This allowed, for the first time, the direct Doppler shift measurements needed

At the Research Laboratories of Brown Engineering Company ( later Teledyne Brown Engineering ), this phenomenon was used in developing the first laser Doppler flowmeter using heterodyne signal processing.

In the decades since the LDV was first introduced, there has been a wide variety of laser Doppler sensors developed and applied.

In December 1955 they published their first measurements of the Doppler shift of ultrasonic signals from a beating heart irradiated by 3 MHz waves.

For the first time, these allowed designers to apply digital signal processing techniques to exploit a variety of broadcast signals and to use cross-correlation techniques to achieve sufficient signal processing gain to detect targets and estimate their bistatic range and Doppler shift.

KFOR-TV eventually became the first station in the country to introduce color Doppler weather radar and in the 1990s, becoming the first television station to broadcast pictures and video of severe weather via cell phones.

The Doppler effect ( or Doppler shift ), named after the Austrian physicist Christian Doppler, who proposed it in 1842 in Prague, is the change in frequency of a wave ( or other periodic event ) for an observer moving relative to its source.

Hubble supported the Doppler shift interpretation of the observed redshift that had been proposed earlier by Vesto Slipher, and that led to the theory of the metric expansion of space.

The Doppler effect ( or Doppler shift ), named after Austrian physicist Christian Doppler who proposed it in 1842, is the difference between the observed frequency and the emitted frequency of a wave for an observer moving relative to the source of the waves.

It proposed to take into account, not just the short-term existence of several particular Doppler shifts, but the entire history of the steadily varying shifts from each target as the latter crossed the beam.

Lewis, head of the AECL Chalk River Laboratories and former Chief Superintendent of the UK Telecommunications Research Establishment ( TRE ) had proposed to the Defence Research Board ( DRB ) a Doppler radar system that avoided both of these problems.

Einstein ( 1907a ) proposed a method for detecting the Transverse Doppler effect as a direct consequence of time dilation.

The Doppler effect, using ultrasonic signals, can be employed to measure the flow of blood without cutting into the blood vessel.

In this work, Doppler postulated his principle ( later coined the Doppler effect ) that the observed frequency of a wave depends on the relative speed of the source and the observer, and he tried to use this concept for explaining the colour of binary stars.

An animation illustrating how the Doppler effect causes a car engine or siren to sound higher in pitch when it is approaching than when it is receding.

Doppler effect of water flow around a swan

The total Doppler effect may therefore result from motion of the source, motion of the observer, or motion of the medium.

In Britain, John Scott Russell made an experimental study of the Doppler effect ( 1848 ).

Variations in the star's radial velocity — that is, the speed with which it moves towards or away from Earth — can be detected from displacements in the star's spectral lines due to the Doppler effect.

Within hours they realized that, because of the Doppler effect, they could pinpoint where the satellite was along its orbit from the Doppler shift.

* Doppler effect

The light from these distant stars and quasars will be redshifted accordingly ( by the Doppler effect and thermalisation ), so that the total light flux from the sky remains finite.

If the object is moving either toward or away from the transmitter, there is a slight equivalent change in the frequency of the radio waves, caused by the Doppler effect.

Sea-based radar systems, semi-active radar homing, weather radar, military aircraft, and radar astronomy rely on the Doppler effect to enhance performance.

If the transmitter's output is coherent ( phase synchronized ), there is another effect that can be used to make almost instant speed measurements ( no memory is required ), known as the Doppler effect.

The Doppler effect is only able to determine the relative speed of the target along the line of sight from the radar to the target.

Any component of target velocity perpendicular to the line of sight cannot be determined by using the Doppler effect alone, but it can be determined by tracking the target's azimuth over time.

Redshifts are attributable to the Doppler effect, familiar in the changes in the apparent pitches of sirens and frequency of the sound waves emitted by speeding vehicles ; an observed redshift due to the Doppler effect occurs whenever a light source moves away from an observer.