The 10 most outstanding astronomical discoveries made by ESO in Chile

1. Stars orbiting the black hole of the Milky Way galaxy

Several of ESO's flagship telescopes were employed in a study conducted over 16 years to obtain the most detailed view of the environment surrounding the monster at the heart of our galaxy, a supermassive black hole.

2. The acceleration of the expansion of the Universe

Two independent research teams, through observations of stellar explosions, including those obtained with ESO's telescopes at La Silla and Paranal, demonstrated that the expansion of the Universe is accelerating. This result was awarded the 2011 Nobel Prize in Physics.

3. Discovery of a planet in the habitable zone surrounding the nearest star, Proxima Centauri.

The long-sought planet, designated Proxima b, orbits its cool red host star every 11 days and has a temperature suitable for liquid water on its surface. This rocky planet is slightly more massive than Earth and is the closest exoplanet to us (and may also be the closest place to harbor life outside the Solar System).

4. Revolutionary ALMA image shows planetary genesis.

In 2014, ALMA, the Atacama Large Millimeter/submillimeter Array, delivered important details of a solar system in formation. The HL Tauri images were the sharpest ever obtained at submillimeter wavelengths. They show how forming planets suck up dust and gas in a protoplanetary disk.

5. The first photograph of an exoplanet

The VLT obtained the first direct photograph of a planet located outside our solar system. It is a giant planet, about five times more massive than Jupiter, orbiting a brown dwarf at a distance equivalent to 55 times the separation between the Earth and the Sun.

6. The first light from a gravitational wave source

A battery of ESO telescopes in Chile has detected the first visible counterpart of a gravitational wave source. These historic observations suggest that this unique object is the result of a merger of two neutron stars. The cataclysmic aftermath of such a merger, long-predicted events called kilonovae, scatters heavy elements such as gold and platinum into the universe.

7. Direct measurements of the spectra of exoplanets and their atmospheres

Through the VLT, it was possible to analyze for the first time the atmosphere surrounding a super-Earth-like exoplanet. The planet, known as GJ 1214b, was studied as it transited in front of its host star and some of the starlight passed through its atmosphere. The atmosphere is mostly water in the form of vapor or is dominated by dense clouds or haze. This is deduced from the first direct measurement of the spectrum of an exoplanet.

8. Independent measurement of cosmic temperature

The VLT detected for the first time carbon monoxide molecules in a galaxy located about 11 billion light-years away, a feat that had been impossible to achieve for 25 years. This allowed astronomers to obtain the most precise measurement of cosmic temperature at such a remote epoch.

9. The most populated planetary system

Astronomers, using ESO's HARPS instrument, discovered a system composed of at least five planets orbiting a Sun-like star known as HD 10180. They also provided evidence for the possible existence of two other planets, one of which may be the lowest mass observed to date. The team also found evidence that the distances between the planets and their star follow a regular pattern, just as in our Solar System.

10. Gamma-ray bursts - their link to supernovae and neutron star fusion

ESO telescopes have provided conclusive evidence that gamma-ray bursts are linked to the final explosion of massive stars, answering a long-held question. In addition, one of the telescopes at La Silla Observatory was able to observe, for the first time, the visible light emitted by a short-lived gamma-ray burst, showing that this category of objects probably originated due to the violent collision of two neutron stars as they merged.