However, the image that accompanies this shocking headline is an illustration. Why? More details -including the Spanish participation in this scientific feat- inside the news.

Illustration of a black hole.

The headline of this news item announces that, for the first time, a black hole has been photographed but the accompanying image is simply an illustration. But hey, don’t leave yet: that photo exists, has been taken by the Event Horizon Telescope (EHT) over ten days and apparently represents Sagittarius A *, the supermassive black hole located in the center of our Milky Way.

The image, according to those responsible, is under investigation, but it is expected that by the end of 2017 the longed-for photo will be made public. For making a photographic simile, the black hole image is like a Polaroid that we will have to shake for a few months to see if it represents exactly what we wanted to photograph or if it looks blurry.

Despite having a mass equivalent to four million soles, Sagittarius A * was a stranger until the mid-1970s, when Bruce Balick and Robert Brown discovered that something it disturbed the orbit of a nearby star, S2. Despite suspicions, they could not immediately identify that it was a black hole.

It took until 2002, when the German Reinhard Genzel revealed that we were talking about a supermassive black hole in the center of our galaxy. “Can black holes and galaxies be two systems that feed each other with an exchange of gas and radiation?” Genzel declared in an interview with EL ESPAÑOL, “we are now having evidence that this is so, it is fascinating what we are learning: it seems to be a close relationship, but we still don’t know if the chicken or the egg came first ”.

This is how the photo was taken

So far, the closest we have to seeing the aforementioned black hole is this image of the European Southern Observatory, in which the gravitational effect of Sagittarius A * leads a dust cloud to move in the direction of the black hole from the blue point (2006) to the green (2010) and finally to the red (2013).

A gas cloud shifted from the blue point (2006) to the red point (2013) by Sagittarius A *.

A gas cloud shifted from the blue point (2006) to the red point (2013) by Sagittarius A *.
ESO / S. Gillessen

Another recent attempt to frame the elusive black hole is this one, from NASA, with X-ray telescopes. What glows in this case is a flash of activity gushing out of the gas clouds surrounding the hole.

Above right, featured image of Sagittarius A *.

Above right, featured image of Sagittarius A *.
NASA

The long-awaited photograph of the black hole occupies the chunk of space between Sagittarius A * and its surroundings to the ‘nearby’ galaxy M87 and is stored on 4,024 hard drives. It has been taken from eight high-frequency radio telescopes located on plateaus or mountains in different parts of the world, including the 30-meter telescope that we have located at Pico Veleta, in Sierra Nevada.

Why is it so difficult to photograph a black hole

First, because they are very small. Sagittarius A * has a mass equivalent to four million suns, but its size is only 17 times larger than our closest star, and that, 25,000 light years away, it’s no big deal.

To this problem must be added another, that a black hole is empty space and that, with a similar concentration of mass in so little space, its gravitational force is so great that it attracts all the light around it.

The combination of several telescopes collecting data at different points on the globe solved one problem, but generated another: How to combine so many and so varied sets of data on space? Because in reality, if this year we finally manage to see the image of a black hole it is thanks to an algorithm, called CHIRP and generated at the Massachusetts Institute of Technology (MIT) by Katie Bouman, a young computer science PhD student, and her team.

When we take a panoramic photograph with the mobile, what the camera does is take different photos and superimpose them like patches. CHIRP does something similar, albeit with a supreme level of complexity: millions of data about space mixed together, which are confused with the composition of our own atmosphere and which were also collected at different times.

Even if this photo turns out to be dirtier than expected, for astrophysicists it will be of enormous value because it can be used to check if Albert Einstein’s theories about gravity are still valid in a space as extreme as the surroundings of a black hole.