Most galaxies are moving away from the expansion of the universe, but M90 is getting closer

In our ever-expanding universe, the light of distant galaxies takes longer to reach us and may one day escape our ability to fully see it. After all, when we explore space millions of light years from space, we see far back in the past. What we observe today may have exceeded our ability to see it or no longer exist at all. That's why it's particularly interesting for scientists to discover parts of our distant universe that seem to be moving. closer overtime. This is exactly what astronomers who captured the last image of the spiral galaxy Messier 90 (pictured above) discovered through their observation.

Hubble representatives provided a statement, reported by LiveScience, that explains how astronomers measure light to calculate the motion of a whole galaxy about 60 million light-years away from us:

The galaxy compresses the wavelength of its light as it moves towards us, as if it were crushed when you press one end. On the spectrum of visible light, the shorter wavelengths appear in blue. Thus, because its light is compressed from our point of view, the Messier 90 presents a phenomenon called "change of blues", which tells the scientists that the Messier 90 is approaching us.

Scientists are measuring the expansion of our universe by looking for the opposite: the redshift. Based on the same principles, redshift indicates a backward movement. Despite the names of these terms, none of them actually indicates a color of light, but rather refers to the human perception of the spectrum of visible light. We perceive the longest visible wavelengths as red. While violet technically represents the shortest end of the spectrum, the blues shift (or negative redshift) is nevertheless the way we describe the compression of the frequency of light that indicates closer proximity.

Image credit: NASA

These terms represent our best approximation of color at such a great distance, but the frequencies of light change when they interact with various materials in the universe. The Earth's atmosphere, for example, acts as a barrier opaque to the vast majority of the electromagnetic spectrum, while remaining almost completely transparent to the ribbon of this spectrum we call visible light. The small amount of visible spectrum absorbed by the Earth's atmosphere gives us the appearance of a blue sky rather than white.

Image credit: ESA

When we look at images of distant galaxies, they tend to look flat – like everything we observe from afar – but the colors of images like that of the Messier 90 give us more than just an aesthetic. A powerful telescope like Hubble uses filters to capture monotonous images of specific frequency ranges of electromagnetic wavelengths. This not only helps to understand the distance of light, but also provides a way to use color to represent that distance in published images. All images in space do not use color for the same purpose, but in context, the color of a captured image can tell you more about what you are looking at. In this case, it is the distance.

The ability to capture images at multiple distances can sometimes impose other restrictions. This is why the last performance of Messier 90 looks like a person who cut a staircase. Powerful imaging systems can capture only a sufficient amount of detail at a given time. Sometimes, the result is missing areas.

Even with the ability to calculate the approximate motion of distant galaxies, we still wonder why Messier 90 seems to be getting closer as most of the universe is moving away from our vision. The scientists hypothesize that this is related to the composition of the Virgo group – a cluster of more than 1,200 galaxies, including Messier 90. The huge mass of the Virgin seems to accelerate the movement of its galaxies into orbits unusual that take them further and further away from our time perspective.

Of course, with about 60 million light-years between the Milky Way and Messier 90, we can only draw these conclusions from the visual data telescopes that Hubble can capture. We still need a lot more data to understand what is happening so far away from us. Although we can capture beautiful images of distant galaxies and find out more about their light, we only look at the light that escapes and has changed during his travels.

The evolution of telescopes and other imaging technologies will allow us to obtain more accurate measurements in the future. We could learn that we looked at a much less complete picture than we thought. Nevertheless, it's amazing to live in a time when we can regularly take stock of the parts of our universe millions of light-years away.

Top Image Credit: ESA / Hubble & NASA, W. Sargent et al.

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