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Introduction:Â
In astronomy, the phrases “light-years” and “parsec” are commonly used to describe distance measurements. Â “Redshift” and “blueshift” are two examples. They’re used to describe how an object moves in space, either toward or away from other objects.Â
Astronomers use the term “blueshift” to indicate an object traveling toward another object or toward us. It is also used to describe the speed at which the galaxy is approaching ours. The spectrum of light emitted by the object is used to determine both redshift and blueshift.
Expanding universe:Â
In the 1920s, American astronomer Edwin Hubble and colleagues discovered that the Universe is expanding by observing that most galaxies are receding from the Milky Way, and
Astronomers measured the spectral shifts of galaxies near and far, a project that is still ongoing in astronomy. It turns out that galaxies are generally receding from us and appear redshifted and not blue-shifted otherwise big crunch would occur. This means that the universe is expanding. Not only that, but we now know that universal expansion is accelerating and that it has accelerated at different rates in the past. This change in acceleration is caused by a mysterious force known colloquially as dark energy.
Doppler Effect:Â
Doppler effect states that if the source moves away from the viewer, the frequency (pitch for sound) and wavelength of both sound and light vary. When it comes to astronomy, the Doppler effect is the sole way to tell if a celestial object is moving toward or away from us along our line of sight. Light from a moving object is blue-shifted, while light from a moving object is redshifted. The amount of blue or redshift indicates the speed at which the object is traveling.
Blueshift:Â
Doppler blueshift is caused by a source moving towards the observer. The term refers to any decrease in wavelength and increase in frequency caused by relative motion, including those occurring outside of the visible spectrum.Â
Light, like sound, is a wave that can be described by its frequency, or the number of wave peaks that pass by each second. A star zooming toward you has its light waves squeezed together, much like a cosmic police car. These light waves appear to have a higher frequency than usual. Because blue is at the high-frequency end of the visible spectrum, light from an approaching star is said to be shifted toward blue, or blue-shifted. Nearby stars, such as Barnard’s Star, are moving toward us, causing a minor blueshift.
Determination of blue shift by astronomers:
Blueshift is measured by astronomers by measuring tiny shifts in the wavelengths of light emitted by the object. They accomplish this using a device that divides light into its constituent wavelengths. This is usually done with a “spectrometer” or another instrument known as a “spectrograph.” The information gathered is graphed into what is known as a “spectrum.” If the light data indicates that the object is approaching us, the graph will appear “shifted” toward the blue end of the electromagnetic spectrum.
Blueshift in galaxies:Â
If the peculiar velocity of a galaxy is toward us and greater than its Hubble recessional velocity, its light will appear blue-shifted. This is possible for nearby galaxies such as Andromeda.
The velocities are in the hundreds of kilometers per second range, and in regions close enough to our own galaxy where the Hubble expansion causes less outward expansion than this, the galaxies’ peculiar velocities only if large enough and close enough to us can overcome the Hubble expansion, causing a blue-shift.
Redshift and Blueshift:Â
In the case of light, the frequency shifts in the direction of the red or blue color due to the relative velocity of the source and observer. When the light moves in the direction of red, the objects are said to be traveling away from each other, and when the light moves in the direction of blue, they are said to be moving towards each other. In fact, while attempting to discern the spectral kinds of stars, this is the first thing that is noticed.
If, the object is moving away and is experiencing a blueshift, where z is the cosmological redshift.
If, there is a redshift and the object is moving away from the observer.
This effect is used to determine the position and other characteristics of objects in space, such as satellite velocity and position. It’s also utilized in radar systems. In astronomy and astrophysics, it has a wide range of applications.
Conclusion:
Thus, the doppler phenomenon when applied to astronomy gives us two major terms redshift and blueshift. Here blueshift is described with its importance, applications, and how it is a technique used by astronomers to study the motions of galaxies toward each other and toward our region of space.
