UNIVERSE
PLANETARY FORMATION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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They produce more red light than nearby galaxies
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They are moving away from us
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The longer wavelengths are filtered out more by dust
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They are moving toward us
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Detailed explanation-1: -Ever since 1929, when Edwin Hubble discovered that the Universe is expanding, we have known that most other galaxies are moving away from us. Light from these galaxies is shifted to longer (and this means redder) wavelengths-in other words, it is ‘red-shifted’.
Detailed explanation-2: -In fact, almost all galaxies are observed to have redshifts. The universe is expanding, and this “cosmological redshift” causes the light from distant galaxies to be stretched (made redder) during the time it travels from the galaxy to our telescopes.
Detailed explanation-3: -When an object is moving away from us, the light from the object is known as redshift, and when an object is moving towards us, the light from the object is known as blueshift. Astronomers use redshift and blueshift to deduce how far an object is away from Earth, the concept is key to charting the universe’s expansion.
Detailed explanation-4: -As a distant galaxy travels away from us, the wavelength of light that it emits stretches and is “redshifted” toward the infrared part of the electromagnetic spectrum. This means that a very distant galaxy emitting primarily visible or ultraviolet light will appear in infrared light by the time its light reaches Earth.
Detailed explanation-5: -Hubble’s law explains that the reason most galaxies are moving away from one another is because the whole universe is expanding.