As a child, Brice Menard he admired with emotion the images of stars, nebulae and galaxies. They inspired him so much that he decided to make his vocation a job, and he studied Astronomy. Decades later, he has been the creator of an interactive map that shows the actual positions and colors of 200,000 galaxies of the visible Universe, from the closest to almost the beginning of everything, the Big Bang. A journey through time and in a totally didactic and public space that can be accessed from here.
The map was created based on data collected over decades by the Sloan Digital Sky Survey project, which has been monitoring the visible sky since the year 2000. Ménard, now a professor in the Department of Physics and Astronomy at Johns Hopkins University and creator of the map together with the computer Nikita Shtarkmanaffirms that its objective is “to show everyone how the Universe really is” and that society understands that all the data behind this map “has given rise to thousands of scientific studies and discoveries.”
Specifically, the Sloan Digital Sky Survey has involved an ambitious effort to capture a large portion of the night sky through the 2.5-meter telescope at the Observatorio Apache Point, in New Mexico. Every night for eight years, the telescope pointed its 120-megapixel camera 1.5 square degrees from the sky—an area about eight times the area of the full moon—shifting slightly to get a wide perspective of space. in front of your target.
It occurred to Ménard and Shtarkman to use all this information to recreate that portion of the Universe and make it ‘accessible’ to the human eye (and much closer to the ordinary citizen). «It was not difficult to generate the map -explains Shtarkman in an explanatory video-, because you already have the data; the difficult thing was to make a good map, because you basically work with the largest scale that exists ». Thus, they created this beautiful view in which each point is not a star, but a galaxy with billions of stars and planets within it. However, among the 200,000 ‘portrayed’, there is no milky waybecause it is the point from which we look: “To see each other we would have to go outside and change the point of view,” explain its creators.
Red, blue and black: the colors of galaxies
We begin the journey at the vertex pixel that symbolizes our galaxy, the Milky Way. “On this map, we’re just a blob at the bottom, just a pixel,” Ménard says. And when I say ‘we’, I mean our galaxy, the Milky Way, which contains billions of stars and planets.”
The beginning of the journey through the Universe. The vertex is the Milky Way
From here we go back in time 2 billion years, to spiral galaxies, very similar to our cosmic neighborhood, with a light blue color. During the tour we can also choose the perspective option as we would see these galaxies in the sky (if we had such a powerful telescope and optimal visibility conditions). In the image we can see how they are related to each other in clusters.
going back a few 4 billion years (and from a distance) we have the elliptical galaxies in an intense yellow. They are very bright, but the stars that form them are much older than those in spiral galaxies.
View of elliptical galaxies
towards the 6 billion years red is taking center stage: «As the Universe expands, photons stretch and objects appear redder. This is the case of elliptical galaxies. At these distances, they appear red to us. As we no longer detect the faintest spiral galaxies, the filamentary structure is less visible,” they explain on the web.
Between 10,000 and 12,000 million For years, blue dyes the entire map: they are quasars, massive black holes located in the center of certain galaxies. “As surrounding gas and stars accumulate, they become extremely bright and can be seen throughout the Universe. Its light is bluish -they explain-. Beyond this distance, galaxies are harder to see. However, we can still see quasars because they are so much brighter and bluer.”
The last points turn red again, since at these distances, the expansion of the Universe is so great that the blue photons from quasars are stretched and appear redder. “A bit further on, we find ourselves in a time when the Universe is filled with hydrogen gas that prevents the propagation of visible light that we could observe today. This time is called the ‘Dark Age‘«. And then the orange, blue and white band which is an actual photograph of the first flash of light emitted shortly after the Big Bangdoes 13.7 billion years. “This light has been stretched by the expansion of the Universe and reaches us in the form of radio waves. It’s called the Cosmic Microwave Background,” the authors note.
Ménard hopes that, in addition to showing the universe in all its beauty, the interactive map will demonstrate the impressive scale of the universe. “We are used to seeing astronomical images that show a galaxy here, a galaxy there, or perhaps a group of galaxies. But what this map shows is a very, very different scale. From this point at the bottom, we can map galaxies throughout the Universe, and that says something about the power of science.”