Andromeda is the nearest galaxy to ours, a dim, cloudy spot in the night sky, bigger than the Full Moon. School books say it is visible with naked eye. But most of us have never noticed it, as the city’s lights hide it.

But now, thanks to ten years of observations from the Hubble Space Telescope, we have the opportunity to see Andromeda as ever again. At the beginning of the year, NASA released an impressive mosaic of images, offering the most clear and detailed view of this spiral galaxy.

“It is amazing that people who have observed Andromeda for millennia can now see it in such details. It’s a gift, “said NASA astrophysicist and a head scientist for Hubble’s mission, Jennifer Wizman.

“We need to stand for a while and feel awe. Because it’s gorgeous. “

Wizman described Andromeda as “our twin brother”, a spiral galaxy like ours, our galaxy. When we observe it, at a distance of 2.5 million light years, it is like looking in a mirror.

Andromeda is about 2.5 million years of light from Earth (one light year is equivalent to about 6 trillion miles). Dozens of smaller galaxies roam her. At its center is an oversized black hole, with a mass of more than 100 million suns, which was detected through the study of the movement of the surrounding stars. Most large galaxies have oversized black holes in their center – and scientists are still trying to understand exactly how they are formed.

Blood blind or huge galaxy?

For most of human history, no one knew what he was seeing when he looked at the “nebula” that looked like a cloud in the constellation of Andromeda. The 18th -century astronomer, Charles Messeier, included it in a list of heavenly objects, was the 31st entry on his list, and became known as M31.

Many astronomers then believed that they were dust and gas clouds. The distinguished astronomer Harlow Sapley believed that there was only one galaxy – our galaxy – and that Andromeda was in it.

Others, however, suspected that they were completely separate galaxies, far from ours.

This led to the so -called “Great Debate” over the scale of the universe. The answer came in the early 20th century, thanks to the discovery of Henryta Swan Livit, a “human computer” at the Harvard Observatory. Livit realized that the variable stars of Kifidas change brilliance at a rhythm that reveals their brightness – and thus their distance from the earth.

Astronomer Edwwin Habel took the next step when he found such a star in Andromeda. On the photographic plate he noted the word “var!”, From “Variable”. The plaque is currently kept in a refractory treasury at the Carnegie Observatories in Pasandina, California.

This discovery proved that Andromeda was another galaxy and not part of ours.

The universe suddenly became much bigger. Habel used a 100 -inch telescope (mirror diameter) on Mount Wilson. A few decades later, on Mount Palomar, the use of a 200 -inch telescope began. And then came the hubble, the space telescope.

It was launched in 1990 with a well -known defect in the main mirror, known as the “spherical diversion”, which made the stars look like deformed spiders. Astronauts visited the telescope and installed a second, smaller mirror that accurately corrected the error. Hubble has become the most famous telescope in the world, with four more missions for repairs and remains a reliable tool, sought after by the world scientific community.

We now know that there are at least 100 billion galaxies in the universe.

A mosaic-daughter of stars

NASA’s new mosaic of images offers new elements about Andromeda’s history, including indications of clashes with other galaxies in the past, according to Benjamin Williams, an astronomer at the University of Washington and head of the program.

Hubble has a limited field of view, as if you were looking at space through a straw, and cannot photograph the entire Andromeda with one shot. The mosaic needed more than 1,000 hubble orbits around the Earth.

The sharpness is so high that astronomers managed to record 200 million stars in Andromeda.

“Pictures like this remind us that we are living in an incredible universe,” said Wisan of NASA.

For years, scientists believe that Andromeda and our galaxy will merge in the distant future. A recent study at Nature Astronomy reports that the probability is 50-50 in the next 10 billion years. Even so, the stars will not collide.

“The stars do not collide with each other,” Williams explains.
“The size of an star is infinite in relation to the distance that separates them.”

The relentless question for anyone studying Andromeda remains: Is there life there? Maybe even intelligent life?

Anyone who observes images of a galaxy, a cluster of galaxies, or the “Deep Field” Hubble snapshots with thousands of galaxies, can only realize how small the earth is in the secular ensemble.

“It’s so beautiful, and it leads us back to the big questions,” says NASA astrophysicist Amber Stron.

“Can’t imagine that maybe, somewhere between the trillion stars, is there another culture that has made his own telescope and is looking at us?”