Viikon kuva

18. marraskuuta 2024: Does this look like science fiction? Well, it is science, but definitely not fiction. In this Picture of the Week, the lasers of ESO’s Very Large Telescope (VLT) are creating artificial stars in the Chilean sky. It’s one of the clever ways in which engineers outwit the biggest enemy of ground-based telescopes: the Earth’s atmosphere. When stars seem to be twinkling, this is the effect of turbulence in our atmosphere. It distorts the signals from space, leading to blurry images. That is why ESO’s telescopes are located high and dry in the desert: a thinner atmosphere means less disturbance. Modern telescopes use adaptive optics to counteract this disturbance and improve their resolution. This is where the lasers come in. They create artificial stars 90 km up in the sky by making sodium atoms in the upper atmosphere glow. During observations, these guide stars are used as reference points, and a ...

11. marraskuuta 2024: Ask someone to describe a desert and they will tell you of sandy, ochre landscapes. Usually, that description is spot on — but not always, like in this Picture of the Week. For most of the year, the white antennas of the Atacama Large Millimetre/Submillimetre Array (ALMA), operated by ESO and its international partners, stand out against the reddish background of the Atacama Desert. Once in a while, though, the landscape transforms, and the antennas become disguised in a white snowy panorama. The Atacama is situated between the Andes and the Chilean Coast Range, high mountain ranges that shield the desert from humid winds, making it one of the driest places on Earth. These conditions make places like ALMA’s site ideal for astronomical observations. Even there, though, sometimes it rains — or even snows. During the winter months of June to September, temperatures can drop to -20 °C and precipitation ...

4. marraskuuta 2024: Back in 1989, the Sky & Telescope magazine announced “The Best Telescope Yet”. More than three decades later, the 3.58-metre New Technology Telescope (NTT) is still an active member of ESO’s telescope family at La Silla Observatory. In this Picture of the Week, the NTT’s distinctive shiny armor stands guard over the barren landscape of the Chilean Atacama Desert. Many of its technological developments were, in fact, breakthroughs that would later be used for ESO’s Very Large Telescope (VLT) and for the future ESO’s Extremely Large Telescope. The NTT's main breakthrough was its active optics system. Telescope mirrors may look perfectly smooth to our eyes, but changes in temperature, wind pressure or the weight of the mirror itself may deform them. But the NTT’s mirror was different: it was mounted on top of a supporting mechanism that corrected these deformations during the observations while monitoring a reference star. This allowed ...

28. lokakuuta 2024: Something odd is happening in NGC 1386, a spiral galaxy located 53 million light years away in the constellation Eridanus. This Picture of the Week combines data from the VLT Survey Telescope (VST), hosted at ESO’s Paranal Observatory in Chile, and the Atacama Large Millimetre/Submillimetre Array (ALMA), operated by ESO and its international partners. When astronomers observed the central regions of this galaxy, they found new stars forming… albeit in a peculiar way. Stars often form within stellar clusters – groups of thousands of stars that originate from massive clouds of molecular gas. The blue ring at the centre of this galaxy is ripe with stellar clusters full of young stars, as seen by VST. A new study led by Almudena Prieto, an astronomer at the Instituto de Astrofísica de Canarias in Spain, used data from ESO’s Very Large Telescope (VLT) and the NASA/ESA Hubble Space Telescope to look at ...

21. lokakuuta 2024: Earth has a majestic new visitor. Seen last week above the ESO Supernova Planetarium & Visitor Centre, the comet C/2023 A3, also known as Tsuchinshan-ATLAS comes to us from the distant Oort Cloud, a gigantic cluster of icy objects that envelops the Solar System. As it got closer to the Sun, it heated up and developed tails of dust and gas observed by comet watchers around the world, including at ESO Headquarters in Garching bei München, Germany. The comet was first detected in early 2023 by two independent facilities: the Tsuchinshan observatory in China and a telescope from the Asteroid Terrestrial-impact Last Alert System (ATLAS), located in South Africa. Since then, it has been getting closer, reaching its closest distance to the Sun in September 2024. Its brightness peaked in early October, and the comet is now dimming down as it embarks on a long journey back home. This object ...

14. lokakuuta 2024: Even though it looks stunning by itself, this Picture of the Week is actually only a tiny part of a 1.5-billion-pixel image of the Running Chicken Nebula. It forms the comb on the running chicken’s head — at least according to some people, because everyone seems to see a different chicken! The data for this gigantic image was captured by the VLT Survey Telescope (VST), a facility of the Italian National Institute for Astrophysics hosted and operated by ESO. But for now, let’s zoom back in on GUM 39, as this nebula is officially called. In the sky, you will find it in the Centaurus constellation, about 6500 light-years from Earth. All around the nebula, orange, white and blue stars are dotting the sky like fireworks. The pink glow that you see are fumes of hydrogen gas, illuminated by the intense radiation from newborn stars. The nebula is also crossed ...

7. lokakuuta 2024: In this Picture of the Week, a solitary antenna points timidly at the Moon. This is not some lonesome telescope, but one of the 66 antennas that together make up the impressive Atacama Large Millimeter/submillimeter Array (ALMA), operated by ESO and its international partners. Humans have been looking at the Moon for as long as anyone can remember, but our eyes only capture a narrow range of wavelengths: visible light. ALMA is different: it can see light at wavelengths thousands of times longer. When ALMA first pointed towards the Moon back in 2008, we saw a version of our satellite under a new light - literally! The radio waves detected by ALMA did not show the Moon’s grey, coarse surface we are familiar with, but its surface temperature, hotter in the areas facing the Sun. Since then, ALMA has been looking at other, more distant moons circling other planets. Will ...

30. syyskuuta 2024: How many vicuñas do you spot in this Picture of the Week?* Vicuñas — a relative of the llamas and the alpacas — roam the Chilean Andes. They feel at home here on the 5000-metre-high Chajnantor plateau, next to their neighbour, the Atacama Large Millimetre/submillimetre Array (ALMA), a state-of-the-art telescope in which ESO is a partner. ALMA consists of 66 antennas, which can be picked up and moved by the giant dark-yellow transporter that also features in this image. The ALMA antennas are located here for a very good reason: the extremely dry conditions at the Chajnantor plateau, deep in the Atacama Desert, are perfectly suited for observing some of the coldest objects in the Universe. In contrast to stars, which are hot, bright and easy to see, these colder objects –– like the clouds out of which stars form –– are often faint in visible light. ALMA observes them ...

23. syyskuuta 2024: Just like the Sun, ESO’s Extremely Large Telescope (ELT) is rising in Cerro Armazones, Chile. With this Picture — or rather: time-lapse — of the Week, you have the chance to enjoy a spectacular sunrise over the largest optical telescope in the world. See the dark spots on the Sun’s surface? In these huge areas, easily the size of a planet, the temperature is lower than on the rest of the Sun’s surface. They can last anywhere from a few days to a few months. The amount of sunspots depends on solar activity, increasing and decreasing in a cycle of around 11 years. A peak is expected in 2025. Here, the Sun is lighting up the ELT construction site, almost like a shadow theatre. The steel dome, in which the telescope will be encased to protect it from the harsh desert weather, is steadily taking shape. Compare this view with ...

16. syyskuuta 2024: Do you feel lost looking at this Picture of the Week? Exploring the gas cloud known as IC2948 means finding your way across countless nascent stars born in this enormous stellar nursery. And yet, this is just a snippet of a much larger object: the Running Chicken Nebula. This nebula spans an area on the night sky close to 25 full moons, and yet, the area you see here is not even a third of a full moon. Obtaining such a detailed snippet of the nebula was possible thanks to a 1.5-billion-pixel image taken by the VLT Survey Telescope (VST), hosted and operated by ESO. Located in the constellation of the Centaur (Centaurus), the Running Chicken Nebula is a labyrinth of gas, dust and young stars whose highly intense radiation erodes away the surrounding material. The gas cloud IC2948 is the brightest region of the nebula. Here, we find creeping ...

9. syyskuuta 2024: This Picture of the Week shows a snippet of the Hydra I cluster, which contains hundreds of galaxies. Each has its own quirks and history — but today, we focus on the story behind the leaky galaxy NGC 3312, which is the largest spiral galaxy known in the cluster. This spiral galaxy, right at the centre of this image, looks almost smudged across the screen, spilling its contents into the cosmos around it. This is NGC 3312, falling victim to an astrophysical robbery: ram pressure stripping. This happens when a galaxy moves through a dense fluid, like the hot gas suspended between galaxies in a cluster. This hot gas drags against the colder gas on the outer shell of the galaxy, ‘pulling’ it off of the galaxy and causing it to leak into the cosmos. This cold gas is the raw material out of which stars form, meaning galaxies losing ...

2. syyskuuta 2024: In this Picture of the Week, the Moon is slowly setting behind ESO’s Very Large Telescope (VLT) in Paranal, Chile. It was taken on August 19 2024 by astronomer and astrophotographer Yuri Beletsky during what is sometimes referred to as a “Super Moon”, a non-scientific name indicating a full moon occurring when the Moon is closest to Earth. Due to its elliptical orbit, the Moon’s distance to Earth varies with time. The closest point is called the perigee, which is why astronomers would call this event a perigee full moon. When this happens, the Moon looks larger than at its average distance — but only by about 7%, which is not much at all. So, how do you take pictures like this, where the Moon looks so big that it dwarfs the very large buildings next to it? First of all, make sure to bring a big telephoto lens with ...

26. elokuuta 2024: For almost 50 years, the ESO 3.6m Telescope has been standing proud at the La Silla Observatory, 2400 metres above sea level. La Silla, on the outskirts of the Atacama Desert in Chile, is the first location where ESO started building telescopes, back in the 1960s. The ESO 3.6m Telescope, hosted in the large dome to the left, first saw light in 1976 and has been searching the skies ever since. During those years, it has looked over thousands of spectacular sunsets like the one in this Picture of the Week. In 1999, this telescope got a full makeover to ensure it remained in good shape for cutting-edge research, with further upgrades done in the 2000s. And you better not underestimate this old machine, because today, it is home to the most successful finder of low-mass exoplanets on Earth! Throughout the years, the telescope has been home to different instruments, ...

19. elokuuta 2024: The glowing red clouds seen in this Picture of the Week show dense gas regions where new stars are being born in the RCW 106 region. But only 1% of this gas will actually go on to create stars, and astronomers don’t know why this percentage is so low. We do know that star formation takes place when regions of these huge clouds of cold gas are able to clump together and eventually collapse into newborn stars, which happens at a critical density. But once we go past that density, do even denser regions produce even more stars, and could this help to explain the 1% mystery? New results from the Atacama Pathfinder Experiment (APEX), accepted for publication in Astronomy & Astrophysics (link accessible from 20 August), suggest this is not the case: denser regions are not more efficient at forming stars. This is perhaps explained by the way these ...

12. elokuuta 2024: At the centre of this Picture of the Week shows are the three telescopes of the BlackGEM array, located in ESO’s La Silla Observatory. BlackGEM is looking for the most intense events in the Universe: the origins of gravitational waves. Different mechanisms can produce these ripples in space-time. For instance, two neutron stars — the collapsed cores of massive stars — can merge in violent spirals, spinning thousands of times per second and emitting powerful signals. In the chaos, precious metals are born into the Universe and colossal magnetic fields cause immense but short bursts of gamma rays. Back on Earth, the LIGO and Virgo gravitational wave detectors can only roughly estimate where these waves may originate. Enter BlackGEM, which quickly scours the target area of the sky with incredible sensitivity to spot the optical light emitted in these events. This allows astronomers to pinpoint their location and study them ...

5. elokuuta 2024: This Picture of the Week shows a very philosophical Mountain Caracara bird, checking himself out near the Atacama Large Millimeter/submillimeter Array (ALMA) telescope’s array of antennas on the Chajnantor Plateau, Chile. What do you reckon he’s thinking about? Maybe, he’s looking at the 66 radio antennas that ALMA uses to probe the clouds of cool gas and dust throughout the cosmos, and thinking about the galaxies that are born in them at the farthest edges of the observable Universe. Maybe he’s thinking about the stars that ALMA watches form, and the stunning spectacles they create when they eventually die. Maybe, he’s thinking about how those very stellar deaths are the origin of all the elements that make up his body — from the calcium in his shiny beak to the carbon-heavy keratin of his feathers, the very same ingredients in our bones and hair — and perhaps, he knows that ...

29. heinäkuuta 2024: This Picture of the Week takes you all the way to ESO’s Paranal Observatory in the Chilean Atacama Desert, to enjoy a spectacular sunset next to the Very Large Telescope (VLT). But that’s not the only wonder displayed by the clear skies of the Atacama. See that blueish glow across the sky? The zodiacal light — also called “false dawn” when seen before sunrise — is a faint, diffuse band of light in the night sky, reaching up from the horizon. It follows the direction of the ecliptic — the plane of Earth's orbit around the Sun. This plane is rich in tiny particles of dust, which scatter sunlight and create this phenomenon. The other planets in the Solar System orbit the Sun in roughly the same plane, and therefore can be often seen within the zodiacal light. In this particular image, Venus is the brightest source and Mars is ...

22. heinäkuuta 2024: Did you know that ESO’s Extremely Large Telescope (ELT) will have a primary mirror (M1) that weighs 200 tonnes, about as much as the largest blue whales? This colossal mirror will rest on the structure that is shown under construction in this Picture of the Week, taken with a drone on July 2024. M1 will be the largest segmented mirror ever built for a telescope, but will need to move constantly and very smoothly during observations while keeping its optical shape, and therefore needs to be held by a cell that is both lightweight and sturdy. Enter the throne that will eventually seat this segmented mirror: the M1 cell seen here. It will hold 798 hexagonal segments that will work together as a single 39-m mirror, staying aligned as the telescope moves, even under varying gravity loads, wind conditions, vibrations or changes in temperature. German company SCHOTT has cast and ...

15. heinäkuuta 2024: This Picture of the Week shows the distant galaxy PJ0116-24, a so-called Hyper Luminous Infrared Galaxy (HyLIRG). HyLIRGs are incredibly bright galaxies, lit up by the extremely rapid star formation within them. But what triggers this? Previous studies suggested that such extreme galaxies must result from galaxy mergers. These galaxy collisions are thought to create dense gas regions in which rapid star formation is triggered. But isolated galaxies could also become HyLIRGs via internal processes alone, if star-forming gas is rapidly funneled towards the galaxy’s centre. In a new paper led by Daizhong Liu (Max-Planck Institute for Extraterrestrial Physics), observations from ESO’s Very Large Telescope (VLT) and the Atacama Large Millimetre/submillimetre Array (ALMA) were combined to study the motion of gas within PJ0116-24. ALMA traces cold gas, seen here in blue, whereas the VLT, with its new Enhanced Resolution Imager and Spectrograph (ERIS), traces warm gas, shown in red. Thanks ...

8. heinäkuuta 2024: ESO’s La Silla Observatory is located on the outskirts of the Chilean Atacama Desert, 600 km north of Santiago de Chile and at an altitude of 2400 metres. As ESO’s first observatory, it has been seeing wonders in the night sky ever since it started operations in the 1960s, but sometimes it also gets to see wonderful things right at its doorstep. The Atacama Desert is the driest place on Earth outside the polar regions in terms of average rainfall. But when rain does fall, complemented by the right temperature and sunlight, it can trigger something spectacular: over 200 different plant species, whose seeds and bulbs lie dormant in the ground during the dry periods, start to bloom. Soon, hundreds of kilometres of otherwise sandy, rocky, and barren desert are covered in purple, pink, and yellow flowers — a phenomenon called “desierto florido” (the flowering desert). Since the weather ...