Milky Way over the Inter-American Observatory

Chile is home to a number of observatories. The most famous of them are the observatories of La Silla and the Paranal Observatory, which have sheltered such famous instruments as the ESO’s Very Large Telescope and VISTA. However, the list of observatories operating in Chile is much wider. And one of them can be seen in the picture below.

Milky Way over the Inter-American Observatory. Source: CTIO/NOIRLab/NSF/AURA/B. Tafreshi

The photo shows a dazzling strip of the Milky Way stretching over the Cerro Tololo Inter-American Observatory. It is located at an altitude of 2200 m above sea level on the top of a mountain. The construction of the Inter-American Observatory began in 1963, and it saw its first light in 1965.

One of the main instruments of the observatory is the 4-meter telescope named after Victor Blanco. From 1976 to 1998, it held the title of the largest optical telescope in the southern hemisphere. To the right of it stands the dome of one of the SMARTS telescopes.

In addition to the Milky Way, a characteristic green stripe can also be seen in the sky. This is not an aurora or an optical illusion. The photographer captured a phenomenon known as the own glow of the earth’s atmosphere. It arises due to the combination of several processes occurring in the upper layers of the gas envelope of our planet. Among them, in particular, are the recombination of ions formed during photoionization under the influence of solar radiation, luminescence caused by the passage of cosmic rays, as well as chemiluminescence, mainly associated with the processes of combining oxygen and nitrogen atoms. The atmosphere’s own glow is visible only in those regions where the sky is dark enough and light pollution does not interfere with its registration.

According to

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