Swedish-ESO Submillimetre Telescope

La Silla Dawn Kisses the Milky Way.jpg
Författare/Upphovsman: ESO/B. Tafreshi (twanight.org), Licens: CC BY 4.0
La Silla Dawn Kisses the Milky Way

This picture was taken just before dawn at the La Silla Observatory, in outskirts of the Chilean Atacama Desert. A layer of orange hovering over the horizon announces the imminent arrival of the Sun. These first hints of daylight are kissed by the Milky Way, which stretches out across the entire night sky. This view of our home galaxy is covered with dark patches, formed from dust particles blocking the light behind them.

In front of this cosmic scenery you can see some of the observatory’s telescopes. The closest is the Swedish–ESO Submillimetre Telescope (SEST), whose dish measures 15 metres across. It was decommissioned in 2003 and replaced by the Atacama Pathfinder EXperiment telescope (APEX) and the Atacama Large Millimeter/submillimeter Array (ALMA). On the plateau in the background stands the ESO 3.6-metre telescope, with the Coudé Auxiliary Telescope (CAT) right behind it.

SEST seems to be pointing at an extremely bright object: This is Venus, one of our neighbouring planets. Venus is lit up by the Sun and outshines all of the stars in the night sky. The triangular white glow that reaches up from the horizon through Venus is called zodiacal light. Zodiacal light is sunlight scattered by dust in the ecliptic — the plane of Earth’s orbit around the Sun.

Observatoire de la Silla - Swedish-ESO Submillimetre Telescope.JPG
Författare/Upphovsman: Franck Schneider, Licens: CC BY-SA 3.0
L'Observatoire de La Silla est un observatoire astronomique professionnel de l'ESO, situé dans le nord du Chili. le SEST 15 m Swedish-ESO Submillimetre Telescope. Mis hors-service en vue du Atacama Pathfinder Experiment, puis d'ALMA.

Dizzying Star Trails over SEST.jpg
Författare/Upphovsman: ESO/José Joaquín Pérez, Licens: CC BY 4.0
The 15-metre diameter Swedish–ESO Submillimetre Telescope (SEST) was built in 1987, and was operated at ESO's La Silla Observatory in Chile until it was decommissioned in 2003.

At the time of construction, SEST was the only radio telescope in the southern hemisphere that was designed to observe the submillimetre Universe, and it paved the way for later telescopes such as the Atacama Pathfinder Experiment telescope (APEX), and the Atacama Large Millimeter/submillimeter Array (ALMA), both located at Chajnantor.

In this image, we see a crowded night sky filled with star trails, a result of the camera's long exposure time. The starlight is reflected back at numerous different angles towards the camera from the giant parabolic dish. In the background, the ESO 3.6-metre telescope stands in its dome, silently surveying the cosmos.

This dizzying picture of the SEST telescope at La Silla was taken by ESO Photo Ambassador José Joaquín Pérez.

Hunting stars.jpg
Författare/Upphovsman: Y. Beletsky (LCO)/ESO, Licens: CC BY 4.0
In this scene, one of the most recognisable constellations in the night sky — Orion (The Hunter), with his famous belt and sword — rises over the slumbering Swedish-ESO Submillimetre Telescope (SEST) at ESO’s La Silla Observatory in Chile.

This mythical collection of stars sits on the celestial equator, making it visible in both hemispheres. Within Orion itself, the distinctive blue and pink hues of the Orion Nebula are visible just above the stellar trio comprising Orion’s Belt. Hundreds of new stars are being forged in the depths of this stellar nursery. Telescopes have observed numerous stars wrapped in cocoons of gas and dust — shrouds that will transform into protoplanetary discs as the turbulent youngsters mature.

This image also captures the noticeably reddish colours of Betelgeuse and Aldebaran — giant stars that belong to the constellations of Orion and Taurus (The Bull) respectively. These stars can be seen to the left of the telescope dish, tracing a curved line down towards the ground. Just before meeting the horizon, this line crosses a fuzzy collection of stars — the Pleiades star cluster. According to classical mythology, Orion was a hunter who chased after the Pleiades, the beautiful daughters of Atlas, in order to find love.