The NSF-DOE Vera C. Rubin Observatory in Chile has unveiled the very first “mega” images of the cosmos obtained thanks to the extraordinary features and wide-field view of its LSST camera—the largest in the world. The camera took nearly two decades to build and involved hundreds of scientists across the globe, including a number of CNRS teams. The world-wide First Look unveiling event is held on 23 June at the National Academy of Sciences in Washington, D.C.

The impressive, car-sized Legacy Survey of Space and Time camera is like nothing seen before: thanks to its 3200-megapixel resolution and the wide field of view of the telescope at the Vera C. Rubin Observatory¹, the LSST camera can photograph 45 times the area of the full moon in the sky with each exposure. The high-definition images, which use six different colour filters, capture the entire southern night-sky in just three nights of shooting. One year after its journey from the United States to the Vera C. Rubin Observatory in Chile, the first “mega” images will be unveiled on 23 June at a press conference held at the National Academy of Sciences in Washington, D.C. This worldwide premiere is the culmination of 25 years of research and construction by international teams, including several research teams from CNRS².  

The exceptional quality of these initial images show that the telescope is ready to start its mission: to scan the entire southern hemisphere sky by taking 1,000 high-definition photographs using six colour filters, every three nights for the next ten years. Studied end-to-end, these scans will provide a high-definition, four-dimensional film of the evolving processes of the Universe. The ten-year project will also generate unprecedentedly rich and profound views of the southern sky and reveal the faintest and furthest-away objects of the cosmos. For the first time on a large scale, this vast survey will reveal the slightest changes in the Universe, from nearby celestial phenomena, such as asteroids and comets, to very distant ones, like supernovae. The project paves the way for major advances in cosmology in dark matter and dark energy, as well as our understanding of our solar system.

In this video, NSF–DOE Vera C. Rubin Observatory showcases 46 subtly pulsating RR Lyrae variable stars in an early glimpse of the dynamic sky Rubin will reveal. Over the next 10 years, Rubin will detect up to about 100,000 of these stars extending out to more than a million light-years away, allowing scientists to map the outer reaches of our Galaxy and explore the structure of the Galactic halo that surrounds the Milky Way and extends nearly halfway to our closest neighbor, the Andromeda galaxy. Credit: NSF–DOE Vera C. Rubin Observatory.

CNRS: a key component of this international project
The project is funded by the U.S. Department of Energy and the U.S. National Science Foundation (NSF). The SLAC National Accelerator Laboratory built the Legacy Survey of Space and Time (LSST) camera. As historic partners, SLAC called on CNRS scientists to help build the focal plane of the camera and help design and build its robotic filter exchange system, which will automatically change the camera’s colour filters—each weighing 24-38 kgs—5-15 times per night. By measuring the quantity of light emitted by night-sky objects, and by converging the images taken through the different filters, it will make it possible to precisely determine their position and distance in relation to the Earth. Other CNRS scientists helped develop the computing infrastructure for the quantitative and qualitative data analysis of the gigantic trove of images that will be collected from the 17 billion observable stars and 20 billion observable galaxies. The goal of this painstaking effort is to create the most comprehensive catalogue of data on the universe. 

Twenty terabytes of collected data will be stored every night. In France, the France Data Facility (IN2P3) (CNRS) in Lyon will store and process 40% of the collected raw image data. This data will be released to scientists around the world at regular intervals to foster groundbreaking discoveries and breakthroughs over the coming decades.

Why develop a ground-based telescope?
Even with 25 space telescopes currently in use, ground-based observation remains essential in documenting the Universe in its entirety. Larger and more sensitive, ground-based instruments produce higher-precision exposures as a result. These instruments also record larger volumes of data than space-based ones, as the remote downloading of data from the latter remains a complex process. Last but not least, ground-based telescopes can also be repaired and improved with increasingly efficient tools. With this state-of-the-art camera, the Vera C. Rubin Observatory is the latest addition to the fifty or so structures operating equipment and infrastructure to observe the universe from Earth and space.

Notes :

1. Named after the American astronomer Vera C. Rubin, who was the first to establish the presence of dark matter in galaxies.
2. From the IN2P3 Computing Centre (CNRS), the Marseille Particle Physics Centre (CNRS / Aix-Marseille Université), the Astroparticle and Cosmology Laboratory (CNRS / CEA / Université Paris Cité / Observatoire de Paris), the Annecy Laboratory of Particle Physics (CNRS / Université Savoie Mont-Blanc), the Clermont Auvergne Physics Laboratory (CNRS / Université Clermont Auvergne), the Subatomic Physics and Cosmology Laboratory (CNRS / Université Grenoble Alpes), the Nuclear Physics and High Energy Laboratory (CNRS / Sorbonne Université / Université Paris Cité), the Institute of Physics of the 2 Infinities in Lyon (CNRS / Université Claude Bernard Lyon 1), the Laboratory of the Physics of the 2 Infinities Irène Joliot-Curie (CNRS / Université Paris-Saclay / Université Paris-Cité), and the Montpellier Universe and Particles Laboratory (CNRS / Université de Montpellier).

Guest Post by Willis Eschenbach

What got me into investigating climate science a quarter-century ago? The astounding stability of the Earth’s global surface mean temperature (GMST). For example, since the year 1900, a century and a quarter, the Earth’s temperature has gone up by 0.46 ± 0.07 percent.

I’ll say it again. In a century and a quarter the Earth has warmed by less than half a percent

The Earth’s climate system is a curious thing. It is a giant solar-driven heat engine. A heat engine is a device that turns heat into mechanical motion. In the case of the climate, the mechanical motion is the endless, ceaseless motion of the ocean and the atmosphere. Like all heat engines, the climate heat engine is heated at the hot end, and then the heat is transferred to the cold end and leaves the engine.

So I started out to discover why the temperature is so stable. Yes, I know that from our tiny human perspective it seems unstable, but for a heat engine, the temperature varying by less than half a percent over a century and a quarter is very stable. And here’s what I found out.

Like all flow systems far from equilibrium, the climate is ruled by the Constructal Law, one of the most under-appreciated discoveries of modern thermodynamics. The Constructal Law governs the evolution of flow systems.

And as the Constructal Law requires, the climate heat engine is constantly evolving to maximize the flow. The Constructal Law is a sort of Ten Commandments for anything that flows—rivers, blood, traffic, and, yes, the climate itself. The basic idea?

Everything that moves is constantly evolving and morphing to make movement easier. Life, it turns out, is just one big game of “How can I get from here to there with the least amount of fuss?” The Constructal Law is why river deltas look like the branches of a tree, which in turn look like the alveoli in our lungs. They are all controlled by the Constructal Law.

From a Constructal Law point of view, the climate is not a fragile, teetering system on the verge of collapse, but a gigantic, heat-hauling Rube Goldberg machine.

The sun pours energy onto the tropics, the poles are the cold end of the heat engine, and the atmosphere and oceans get busy shuttling all that heat from the equator towards the poles, where it escapes to space far more easily than at the tropics. Here’s a map of what areas lose or gain energy by this flow.

Figure 1. Average of flow of heat which is constantly being exported from the tropics to the poles, March 2000 to February 2024.

According to Bejan, the climate doesn’t maximize temperature, or CO₂, or even the number of climate conferences in Paris.

No, what it’s really maximizing—relentlessly, remorselessly, every minute of every day—is the flow of heat from where it’s hot to where it’s not.

Picture the earth as a planetary HVAC system, always rearranging its ductwork to get the job done faster. The Hadley cells, the jet streams, the ocean currents—none of these are accidents or the result of a committee meeting. They’re the system’s way of morphing itself to maximize that poleward heat flow. The boundaries between the warm and cold zones, the size of the tropical belt, the speed of the trade winds—Bejan’s math predicts them all and the numbers line up with the real world.

And here’s the kicker: when you let the system optimize for maximum heat transport, a bunch of other things fall into place. The average surface temperature, the temperature difference between the equator and the poles, the total amount of heat getting shunted north and south—Bejan’s model nails them all, without the need for fudge factors, hand-waving, or appeals to the climate gods.

How do I know that? I know because I created and ran what I believe is the first actual real-world based exemplar of Bejan’s theoretical climate model on my computer and saw how successful it was. The whole process is described in the post below.

So what’s the grand takeaway?

The climate isn’t a delicate flower, always on the verge of wilting. It’s a brawny, self-organizing, heat-moving machine, always rearranging its own plumbing to maximize the flow from hot to cold. It doesn’t care about our politics, our models, or our carbon taxes. It just wants to get the job done, and it’ll keep morphing until it does.

In short: if you want to understand the climate, stop thinking about balance, and start thinking about flow in a constructally-ruled world. The Earth’s climate is a heat engine with a mission, and it’s not going to let a little thing like equilibrium get in its way.

My best wishes to all,

w.

Of Course … when you comment, I politely ask that you quote the exact words you are discussing. Makes things clear.