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All eyes on the Milky Way

Anyone admired the night sky will perhaps surprising to believe that our eyes are really blind than most of the "light" which comes from the universe. What we perceive is, in fact, only a small fraction of the energy that stars, galaxies and other astronomical sources produce.

The so-called light "visible" is but a fraction of what scientists call the "electromagnetic spectrum: radio waves, microwaves, infrared light correspond to lower energies than visible light, ultraviolet light, X rays and rays range rather have higher energies, but it's still light. The atmosphere

Earth, also contributes to our "isolation" taking some of this radiation and allowing only visible light and radio waves. If there were no atmosphere, and if our eyes have evolved in some of the countless other ways, probably the night sky would appear in a different way.

Thanks to technological advances of recent decades, astronomers have learned to look at the sky but also in other energy, thus creating innumerable discoveries. Using space telescopes that scan the universe from a privileged location outside the atmosphere, in orbit around the Earth, have been able to open "new eyes" on cosmos, observed by light infrared and ultraviolet, through X-rays, gamma rays and microwave .

In particular, the images of the same object made of different "bands" of energy reveal the wide range of physical phenomena that occur within it. This image, released last Tuesday by NASA, it is a shining example.


For being portrayed is the center of our galaxy, the Milky Way, which is hidden inside a supermassive black hole with a mass equal to four million times that of the Sun, whose presence you can not directly observe only sense in an indirect way. The different colors in the image correspond to observations made in different energy bands, and reflect different physical phenomena.

what he sees Hubble Space Telescope in visible light and the so-called "near-infrared, is shown in yellow: it is hundreds of thousands of stars, some of which are emerging while others shine, burning the their nuclear fuel. In red, however, shows the observations made by the infrared Spitzer Space Telescope. The infrared light corresponds to lower energies than visible objects Spitzer is so sensitive to colder than to Hubble, and can "see" the filamentary structure of the clouds of cosmic dust , forged by winds generated by nearby stars, and from which new stars are born in the future. Blue and purple, finally, to the observed data are reproduced by the Space Telescope Chandra X-ray: X-rays are emitted by gas at very high temperatures, over a million degrees, which is located near the galactic center, so warm thanks to 'energy released from the nearby stellar explosions and energy jets from the black hole hidden in the heart of the Milky Way.

combining the images obtained with different telescopes, astronomers have been able to discover previously unknown details about the phenomena violent and impetuous that take place in the center of our Galaxy, about 26.000 years-light from us.

CLAUDIA MIGNONE

This image, about the size of the full moon in the sky, shows the rising stars, explosions, clouds of gas and dust in the Milky Way's center. The different colors correspond to observations in different bands of the electromagnetic spectrum: the yellow is in the visible and near infrared observations (Hubble), red is infrared observations (Spitzer), the blue-violet shows the X-ray observations (Chandra). Image released by NASA, ESA, CXC, SSC, STScI.