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Interactive map showing the scale of the universe with 200,000 galaxies


Now, there’s a way for everyone who’s ever dreamed of being an astronaut to observe the universe from the comfort of their own home: an interactive map of the known universe.

The new map lets you see some 200,000 galaxies laid out in their actual locations in space and color, including parts of space so far away that they give a glimpse of the Big Bang great.

It is a view of the immense scale of the observable universe that was previously only accessible to scientists.

Johns Hopkins University astronomers have used data collected over the past two decades by the Sloan Digital Sky Survey to unlock the night sky for the public.

The idea for the map came from Brice Ménard, a professor at Johns Hopkins, who said he grew up looking at astronomical pictures of stars, nebulae and galaxies.

It was that beauty that he wanted to share more widely.

“Astrophysicists around the world have been analyzing this data for years, leading to thousands of scientific papers and discoveries,” he said in a press release. non-scientists. Our goal here is to show people what the universe really looks like.”

He and former Johns Hopkins computer science student Nikita Shtarkman compiled a map of galaxies together.

When zoomed out, the photo looks like a slice of pizza in colorful pixels — an upside-down triangle containing countless tiny dots in different bands of color.

But each dot isn’t just a star — it’s a galaxy.

The farther a galaxy is from Earth, the longer it takes for light to reach us, meaning this map also looks deeper into the past. The map allows us to look back in time to 13.7 billion years.

The Sloan Digital Sky Survey is a project based in New Mexico where a telescope has carefully mapped the night sky by pointing in different directions to slowly collect bits of information. believe. Only a portion of the data it has collected is used to create this new map.

“It has already collected data on millions of galaxies out there,” Menard explains in a video from Johns Hopkins University.

Menard said in the video that although there are thousands of individual images of galaxies, he wanted to compile a map that gives a sense of the sheer scale of the observable universe.

“Seeing the vastness of the universe, it’s quite inspiring,” he said.

The map doesn’t contain the full depth of the night sky — it shows all the galaxies packed into one thick “slice” as measured by the telescope as it swam across the sky. A full map would be spherical and also filled with galaxies so scattered that it is hard to visualize.

Shtarkman says in the video that the amount of data available makes it easy to create a map, but it’s difficult to organize it into a user-friendly map.

“You are basically working on the largest scale available,” he said.

The map, accessible online or free to download, allows viewers to zoom in on the center and get a better look at how many galaxies are grouped together in the image.

As you scroll back in time, the colors on the map change. This gradient isn’t just for show — the colors of galaxies as they appear before our eyes are actually part of how scientists understand how far galaxies or stars are from us. The wavelengths of light are shifted to become longer and redder as they move away from us with the constant expansion of the universe, a term known as “redshift”.

The map explains spiral galaxies like the Milky Way, which is “dim and blue”, and elliptical galaxies, “which are yellowish and much brighter than spiral galaxies.” Behind these two galaxies is a red-shifted elliptical galaxy, which is now much harder to see.

Around 7.3 billion years ago, galaxies became largely invisible, replaced on the map by brighter quasars, which are massive black holes at the centers of some galaxies and emit light. bright green when they draw light on them.

After 11 billion years, even quasars are redshifted. And then, after 13.7 billion years, there was a bright band of orange and cyan — the “first light” emitted by the Big Bang, picked up as radio waves known as the Cosmic Microwave Background. .

“We couldn’t see anything beyond this point,” the map said. “The time it took for light to reach us is older than the age of the Universe.”

The map also allows viewers to visualize what the night sky would be like if we could see all of these galaxies with the naked eye in an impressive series of images.

At the bottom of the triangular map, the point where all the galaxies radiate outward, there is a small label: “You are here.”

“In this map, we’re just a small dot at the bottom, just one pixel,” Menard said in the release. “And when I say us, I mean our galaxy, the Milky Way, with billions of stars and planets. We often see astrophotography showing 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 little speck at the bottom, we can map galaxies across the entire universe, and that says something about the power of science.”

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