March 15 Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2022 March 15

A Road to the Stars

Image Credit: ESOPetr Horálek (ESO Photo AmbassadorInst. of Physics in Opava)

A stunning night view, taken close to the 1.54m Danish Telescope and the 3.6m telescope on the road at La Silla, shows the Milky Way above the horizon, accompanied by the Magellanic Clouds. ESO’s 3.6m Telescope, seen here atop a hill at the centre of the image, is home to HARPS, an instrument dedicated to the discovery of planets outside the Solar System via the radial velocity method. This method enables the detection of a planet by measuring the wobbling motion of the central star caused by the gravitational pull of the planet itself.  The towers on the left are the support structures of the BlackGEM telescopes, which had not been installed yet when this image was taken. BlackGEM is an array of telescopes that will search for the light emitted by the optical counterparts of the most powerful gravitational-wave sources, namely colliding neutron stars and black holes.  On the right of the image, we see the Large and Small Magellanic Clouds, two irregular dwarf galaxies orbiting the Milky Way at a distance of approximately 160 000 and 200 000 light-years, respectively. In the Mapuche culture of south-central Chile, these neighbouring galaxies were known as lafken, labken or künchalabken (“the lagoons”) as well as rünanko (“the water wells”). [1] The red filamentary emission stretching across the sky in the horizon is called airglow, which is light naturally emitted by atoms and molecules in the atmosphere through various physical and chemical processes. Despite showing up prominently in this image, airglow is invisible to the unaided eye.   [1] Source: Wenumapu. Astronomía y Cosmología Mapuche, Gabriel Pozo Menares & Margarita Canio Llanquinao
Explanation: Pictured — a very scenic road to the stars. The road approaches La Silla Observatory in Chile, with the ESO‘s 3.6-meter telescope just up ahead. To the left are some futuristic-looking support structures for the planned BlackGEM telescopes, an array of optical telescopes that will help locate optical counterparts to gravitational waves detections by LIGO and other detectors. But there is much more. Red airglow illuminates the night sky on the right, while the central band of our Milky Way Galaxy slants across the image center. Jupiter can be seen just above the band near the image center, while Saturn is visible just above the 3.6-meter telescope dome. The two largest satellite galaxies of our Milky Way Galaxy, the LMC and SMC, are seen on the far right. The featured image panorama was built up from multiple 15-second exposures that were captured on 2019 June 30. Two days later, La Silla experienced a rare total eclipse of the Sun.