ATacama At Night --- ATAN

Situated in the heart of the summer Milky Way, this nebula represents the best proof that the galaxy is still alive and in continuous evolution. This enormous expanse of ionized gas is heated and made visible by the numerous hot, young stars born within. You can notice dark columns inside, called the Pillars of Creation. They aren’t zones lacking gas; in fact, they are anything but. There inside, hidden from view, those columns of dense , cold gas and dust are giving birth to new stars and probably planetary systems. Subjected to their own gravitational pull, those dense clouds of gas and dust begin a slow gravitational collapse which breaks them into many smaller clouds from which the single stars will be born.  The compression increases the heat in the central area, where a protostar is formed: an aggregate of gas, much more extensive than the star will be, and which only emits gravitational energy. The rotation of the gas, for the principle of preserving the angular mom...

All the colors of the Cosmos in one image. The region around Antares (the brightest star, below) and Rho Ophiuchi (above) is a treasure chest full of colorful gems, unique in our sky. In this image different colored stars are easily noticed (the blue ones are hotter than the red-orange ones), two globular clusters and a thick fabric of chiaroscuros in different tones.  The long dark rivers are populated by very cold gas, at around -436°F, and large quantities of dust. The blue region near the top is a reflection nebula, like the one of the Pleiades. The small red region at right, on the other hand, is an emission nebula, with the typical color produced by the rearranging of hydrogen atoms (there isn’t just hydrogen, but you can only see hydrogen’s imprint: they’re two different things!).  In short, the orange nebula on top of Antares is an extremely rare case of an orange reflection nebula. Usually, the gas illuminated by starlight, but not heated enough to beco...

The globular Omega Centauri, now considered a remnant of a dwarf galaxy, is among the most beautiful representatives of this category, so bright that it is well visible even to the naked eye as a very faint star.  We’d never expect, however, that that indistinct dot, seen with a telescope and a camera, is literally bursting with stars. Hundreds, thousands and even millions of tightly enveloped stars that truly seem to form, this time, an impenetrable curtain. Finally, for once, our eyes are right, because millions of stars are contained in a sphere with a diameter of hundreds of light years. If we could observe the sky from a hypothetical planet set in the proximity of the central region, we would see the night illuminated as day and constellated by dozens of stars brighter than our full Moon.  The density of the stars in the center of the globular clusters is a thousand times greater than that of our galactic environment. In this chaotic place, true territorial...

Hidden from European Culture until 1503, these two cosmic clouds are some of the most beautiful treasures of the Southern Hemisphere. Their tracks were brought to our knowledge by the explorer Amerigo Vespucci and just 21 years later were called the Magellanic Clouds, in honor of the leader of the first expedition to circumnavigate the earthly globe. Already, with a careful look without instruments a certain resemblance to the starry clouds of the Milky Way can be noticed. We don’t see the single stars but their colors, contrasts and even shapes let us intuit that they might be pieces of our Galaxy, populated by billions of stars. A small telescope confirms our impression making billions of miniscule dots, darker zones covered by dusts and luminous spots that we’ll soon learn to recognize as nebulae.  The Magellanic Clouds are big star systems more than 93,000 light years away, one and a half times the size of our Galaxy. Therefore, we’re not observing clouds in our ...

In the southern hemisphere, the central zone of the Milky Way, so elusive at our latitudes, travels very high on the horizon and is able to shine faintly on the ground, creating soft and diffused shadows. In the planet’s remotest places, this is the only source of nocturnal light and this is the reason it seems to shine even brighter, to the point that one has the sensation of being overwhelmed by the immensity of the Universe.  You can see everything in the following photograph, which shows a panoramic view of the Galaxy observed in the uncontaminated Atacama desert sky. That impetuous column of light superimposed over the dense central zones isn’t light pollution or the Galaxy’s light. It’s the zodiacal light: billions of thin and miniscule dust particles roaming in the Solar System are illuminated by the Sun and diffuse a tiny percentage of its light, which can brighten the panorama in the total dark of those uncontaminated places.

The grandeur of the summer Milky Way (winter for southern hemisphere) across almost the entire sky can be seen very well in this 30 seconds shot taken from the Atacama desert. The view is similar with the naked eye in a very dark sky, even though the contrasts are not nearly as sharp and our eyes can’t see the real colors which, instead, any camera can emphasize.  There is an impenetrable wall of stars in front of us; this is the only thing that comes to our mind. How is it possible for them to be so compressed together? How can they avoid colliding with each other?  We’re in a place unknown to us and our experience, where space is compressed and makes us see objects as though they were all at the same distance.  The truth is that we are observing a crack tens of thousands of light years deep and objects that emit immense amounts of energy. The result? That on an average that sea of stars has the same density as the place where the Sun is: the stars al...