DEN HAAG (ANP) - Minister Thierry Aartsen (Werk en Participatie, VVD) roept werkgevers op om hun personeel niet te dwingen naar het werk te komen bij deze hitte. "Ik vraag hen coulant te zijn." Volgens hem zijn heel veel werkgevers dat ook al. "En werknemers: denk vooral aan jezelf. Als je je er niet comfortabel bij voelt, hoef je van deze minister niet naar het werk te komen."

Deze vrijdag kan het op plekken meer dan 40 graden worden. Het KNMI heeft daarom code rood afgekondigd vanwege extreme hitte in acht provincies. Een van de adviezen is dan om niet de weg op te gaan, tenzij het écht moet.

Evenwel ziet Aartsen er niets in om vanaf een bepaalde temperatuur werknemers het recht te geven om niet naar het werk te hoeven. "Laten we dat alsjeblieft niet in de wet regelen", verzuchtte hij vrijdag voorafgaand aan de ministerraad. "We zijn allemaal volwassen mensen. Werkgevers en werknemers moeten er samen voor zorgen dat het prettig werken is."

DE BILT (ANP) - Het KNMI geeft code geel af voor zaterdagavond vanwege zware onweersbuien. De weerswaarschuwing geldt voor heel Nederland.

Tijdens de buien kan veel neerslag vallen en kunnen windstoten oplopen tot 100 kilometer per uur. Ook waarschuwt het weerinstituut voor grote hagelstenen. Die kunnen tussen de twee en vijf centimeter zijn. De onweersbuien kunnen op meerdere plaatsen voor overlast en schade zorgen.

Het weerinstituut gaf eerder al code oranje af vanwege extreme hitte. Vrijdag is het de warmste 26 juni ooit in Nederland gemeten.

TAIPEI (ANP/AFP) - Een Taiwanees scheepvaartbedrijf heeft bevestigd dat een containerschip in de Straat van Hormuz is geraakt door een "onbekend object". Het gaat goed met de bemanning, de lading en het schip zelf, stelt containerrederij Evergreen Marine Corp.

Het bericht volgt op meldingen dat donderdag een vaartuig onder vuur was genomen in de belangrijke waterweg voor de Iraanse kust. De krant The New York Times schreef dat het ging om een Iraanse aanval met een drone op een schip van Evergreen Marine. Die volgde op Iraanse waarschuwingen dat schepen hun doortocht moeten afstemmen met de Revolutionaire Garde.

Evergreen Marine meldt niet dat het ging om een Iraanse drone-aanval, maar laat wel weten dat onder meer de ramen op de brug en andere delen van het schip beschadigd zijn na een inslag. "De hoofdmotor en alle navigatieapparatuur bleven normaal functioneren, en er waren geen problemen die de zeewaardigheid van het schip in gevaar brachten."

BRUSSEL (ANP) - In de EU zijn ruim 700 criminele netwerken actief, meldt EU-politiedienst Europol. De criminele netwerken houden zich bezig met drugssmokkel, cybercriminaliteit, mensensmokkel, fraude en witwassen. Naar schatting zijn zo'n 400.000 mensen actief binnen die netwerken uit 118 verschillende landen.

85 procent van de netwerken gebruikt legale bedrijfsstructuren. Volgens Europol laat dat de omvang, het bereik en de grenzeloosheid van de netwerken zien. EU-lidstaten zouden daarom veel meer moeten samenwerken om de criminele netwerken tegen te gaan.

Verder noteert Europol dat de netwerken zich razendsnel ontwikkelen. 80 procent van de groepen die twee jaar geleden in kaart waren gebracht, zijn er nu niet meer, ofwel omdat ze ontmanteld zijn, verplaatst of vervangen. De criminele netwerken "opereren niet langer geïsoleerd. Ze zijn onderdeel van een dynamisch crimineel ecosysteem dat zich snel aanpast aan verstoringen, gaten opvult en nieuwe criminele kansen grijpt", aldus Europol.

DEN HAAG (ANP) - Verschillende musea zijn vrijdag gratis toegankelijk voor mensen die verkoeling zoeken vanwege de hitte. Onder meer Museum Catharijneconvent in Utrecht, het Stedelijk Museum in Schiedam en Museum Rembrandthuis in Amsterdam openen de deuren voor iedereen die op zoek is naar een koelere plek.

In Museum Catharijneconvent kunnen bezoekers gratis naar binnen tussen 11.00 en 17.00 uur, onder meer in de koele kloostergangen en de Pandhof. Museum Rembrandthuis is vrijdag tot en met zondag open voor alle Amsterdammers. Op vertoon van post met een Amsterdams adres zijn zij van 10.00 tot 18.00 uur welkom in het "koele 17de-eeuwse woonhuis" van Rembrandt, schrijft het museum.

Stedelijk Museum Schiedam bood de afgelopen twee dagen al een gratis koelteplek aan en doet dat ook vrijdag. Mensen kunnen er terecht voor water, een toilet of om "gewoon even bij te komen". Ook kunnen zij gratis een groot deel van het museum bezoeken.

In Leiden kunnen 70-plussers voor verkoeling gratis naar binnen bij Rijksmuseum Boerhaave. Naturalis stelt de begane grond open.

Researchers say they detected the first gravitational-wave "fingerprints" of a black hole's event horizon by analyzing the final moments of the powerful GW250114 merger. The findings support Einstein's general relativity and may eventually help probe frame dragging and quantum fluctuations near black holes. Phys.org reports: For the new research published in Nature, an international team of researchers analyzed data from the strongest gravitational wave ever recorded, known as GW250114, detected by the LIGO observatory in January 2025. By isolating the last burst of waves -- known as "direct waves" -- from this black hole merger, the scientists said they were able to extract information from closer to an event horizon than ever before. "This black hole horizon concept normally appears in science fiction," lead study author Sizheng Ma of the Perimeter Institute for Theoretical Physics in Canada told AFP. "But now we are really able to touch the region around the horizon with gravitational data," he added. "Sometimes I cannot believe this is really happening."

The last stage of two black holes merging is like a spoon stirring a glass of water, Ma explained. The resulting swirl in space creates the ripple of gravitational waves that travel at the speed of light in all directions. If the metaphorical spoon is stirring close enough to the black hole's event horizon, "this offers us a chance to decode the physics around that region," Ma said. By supporting the theory of general relativity, the results "proved that Einstein was correct again," he added.

The scientists emphasized that more research was needed to decipher what can be gleaned about event horizons using this method. But they did detect information about how black holes twist space around themselves as they rotate -- a phenomenon known as "frame dragging." "This is similar to pushing a glass into a table and twisting it, so that the tablecloth winds up around it," Maximiliano Isi, a gravitational wave astrophysicist at Columbia University, told AFP. In the future, the scientists hope to find signs of tiny changes known as quantum fluctuations. "In this way, we can really probe this near-horizon region to look for new physics," including searching for a deviation from general relativity, Ma said.

Read more of this story at Slashdot.

europeanspaceagency posted a photo:

This Copernicus Sentinel-2 image shows agricultural development in the desert of southern Egypt, close to the border with Sudan.

Egypt is over 95% desert, making a very small proportion of its land suitable for agriculture. As the demand for food grows, the need for agricultural development in desert areas has intensified. This comparison highlights an important land reclamation project, where Egypt’s Western Desert is being used for agriculture, and how it has developed between 2015 (here) and 2025 (here).

Thise false-colour image has been processed using Sentinel-2’s near-infrared channel to display vegetation in red – a particularly stark contrast to the desert areas across the region. The resulting range of colours, from red to brown, is a more accurate representation of different types of crop or different growth stages, compared to true-colour images.

Such satellite data are therefore useful in agricultural monitoring for mapping and classifying land use, crop type, crop health, change detection, irrigated landscape mapping and crop area mapping.

Changes over the past 10 years are clearly visible in the images. In 2015, the barren landscape of south Egypt looked like any other desert. But over time, land cultivation has increased, transforming the area into viable agricultural land by 2025.

The shapes of the fields indicate the irrigation method used. Most of the cropland is divided into circles, up to 800 m wide. This is due to the central-pivot irrigation system, with water supplied by a set of sprinklers rotating around a well at the centre. Since no crops can grow in this climate without intensive irrigation, the fields are perfectly round. This type of irrigation helps farmers manage their watering demands and conserve precious resources.

Canals can be seen as thin, black lines cutting through the agricultural fields and supplying water from Lake Nasser, visible in black on the bottom right. One of the largest artificial reservoirs in the world, Lake Nasser is the result of the construction of a dam across the waters of the Nile to provide irrigation in the nearby areas.

In the 1980s and 1990s, the diversion of water from Lake Nasser created the Toshka Lakes featured in the top left corner. These endorheic lakes are filled by overflow from Lake Nasser through a manmade canal, clearly visible in the 2015 image snaking its way into the Sahara Desert.

The comparison also reveals extreme variations in the lakes over time. The rise and fall depend on fluctuations in water flow from the Nile. Between 2012 and 2018, the lakes had shrunk significantly, leaving only small remnants of water in the basins, as visible in 2015. Summer rainfall in Sudan in 2019 and record-breaking floods in 2020 rapidly replenished the lakes, which appear fully filled in 2025.

Copernicus Sentinel-2 plays a key role in mapping differences in land cover to understand how it is used over time. While providing detailed information about Earth’s vegetation, the mission also measures water quality and detects changes in water bodies, supporting sustainable water management – a valuable tool for arid areas where water is scarce.

Credits: contains modified Copernicus Sentinel data (2025), processed by ESA; CC BY-SA 3.0 IGO

europeanspaceagency posted a photo:

The subject of today’s ESA/Hubble Picture of the Month is an ancient inhabitant of our galaxy. This sparkling scene is of a globular cluster: a collection of tens of thousands to millions of stars, all tightly bound together under the influence of gravity. Astronomers know of more than 150 globular clusters in our galaxy, though there may be others yet to be discovered, hidden from view by dust or densely packed fields of stars.

This particular globular cluster is NGC 6723, sometimes called the Chandelier Cluster. Much like its namesake, this cluster sparkles with countless lights — but each ‘lightbulb’ in this chandelier is an individual star 27 000 light-years away in the constellation Sagittarius (the Archer).

Globular clusters like NGC 6723 contain some of the oldest stars in our galaxy. The ages of these clusters often exceed 10 billion years old, and some are nearly as old as the Universe itself. Globular clusters are thought to be some of the first structures to have formed in our galaxy, coalescing potentially billions of years before the thin disk of stars in which our Sun orbits. The details of how globular clusters formed, however, are not yet certain.

Astronomers initially thought that all stars in a globular cluster formed at the same time in a single flourish of star formation. This would mean that all stars in a globular cluster would be the same age and be made of the same mixture of chemical elements. Now, thanks to observations from telescopes like Hubble, researchers know that these seemingly simple stellar populations have more complex histories than originally thought.

Hubble first observed NGC 6723 as part of an ambitious survey dedicated to demystifying the properties of globular clusters in our Milky Way galaxy. In this observing programme (#10775, PI: Sarajedini), researchers used Hubble to study 65 globular clusters in our galaxy in visible and near-infrared light. These data allowed researchers to study everything from the ages of globular clusters to the process through which massive stars sink to the centre of a star cluster and lower-mass stars drift toward the cluster outskirts. This survey has been immensely scientifically valuable, and these observations have inspired several hundred published research papers.

In a later observing programme (#13297, PI: Piotto), researchers set their sights again on many of these same clusters, including NGC 6723. This time, they used Hubble’s unique sensitivity to ultraviolet light to detect the subtle variations in chemical composition between the stars of globular clusters and determine the age spread among the clusters’ stars. For NGC 6723, researchers found evidence of two closely-spaced periods of star formation, the second occurring within 634 million years of the first. (‘Closely-spaced’ is relative; 634 million years is a blink of an eye for a star cluster that is more than 10 billion years old!)

Thanks to these findings, astronomers are on the path to understanding how and when globular clusters formed — and Hubble observations of celestial chandeliers like NGC 6723 are lighting the way.

[Image Description: A globular cluster. It is made up of many thousands of bright stars, tightly-packed in the centre and more spread out at the corners, but filling the entire view. The stars are coloured either orange or bright blue, with the blue stars mainly concentrated in the centre. Orange stars are located mainly around the edge, and also vary in size from small dots to glowing stars with four points, based on their position in the foreground or background of the cluster.]

Credits: ESA/Hubble & NASA, A. Sarajedini, G. Piotto; CC BY 4.0

europeanspaceagency posted a photo:

This Copernicus Sentinel-2 image shows agricultural development in the desert of southern Egypt, close to the border with Sudan.

Egypt is over 95% desert, making a very small proportion of its land suitable for agriculture. As the demand for food grows, the need for agricultural development in desert areas has intensified. This comparison highlights an important land reclamation project, where Egypt’s Western Desert is being used for agriculture, and how it has developed between 2015 (here) and 2025 (here).

Thise false-colour image has been processed using Sentinel-2’s near-infrared channel to display vegetation in red – a particularly stark contrast to the desert areas across the region. The resulting range of colours, from red to brown, is a more accurate representation of different types of crop or different growth stages, compared to true-colour images.

Such satellite data are therefore useful in agricultural monitoring for mapping and classifying land use, crop type, crop health, change detection, irrigated landscape mapping and crop area mapping.

Changes over the past 10 years are clearly visible in the images. In 2015, the barren landscape of south Egypt looked like any other desert. But over time, land cultivation has increased, transforming the area into viable agricultural land by 2025.

The shapes of the fields indicate the irrigation method used. Most of the cropland is divided into circles, up to 800 m wide. This is due to the central-pivot irrigation system, with water supplied by a set of sprinklers rotating around a well at the centre. Since no crops can grow in this climate without intensive irrigation, the fields are perfectly round. This type of irrigation helps farmers manage their watering demands and conserve precious resources.

Canals can be seen as thin, black lines cutting through the agricultural fields and supplying water from Lake Nasser, visible in black on the bottom right. One of the largest artificial reservoirs in the world, Lake Nasser is the result of the construction of a dam across the waters of the Nile to provide irrigation in the nearby areas.

In the 1980s and 1990s, the diversion of water from Lake Nasser created the Toshka Lakes featured in the top left corner. These endorheic lakes are filled by overflow from Lake Nasser through a manmade canal, clearly visible in the 2015 image snaking its way into the Sahara Desert.

The comparison also reveals extreme variations in the lakes over time. The rise and fall depend on fluctuations in water flow from the Nile. Between 2012 and 2018, the lakes had shrunk significantly, leaving only small remnants of water in the basins, as visible in 2015. Summer rainfall in Sudan in 2019 and record-breaking floods in 2020 rapidly replenished the lakes, which appear fully filled in 2025.

Copernicus Sentinel-2 plays a key role in mapping differences in land cover to understand how it is used over time. While providing detailed information about Earth’s vegetation, the mission also measures water quality and detects changes in water bodies, supporting sustainable water management – a valuable tool for arid areas where water is scarce.

Credits: contains modified Copernicus Sentinel data (2015), processed by ESA; CC BY-SA 3.0 IGO