This week's science news was all about goings on in space, with reports that the James Webb Space Telescope (JWST) picked up a signal from a mysterious, never-before-seen substance on Pluto and Titan.

The space telescope detected a specific absorption line in the spectra of these worlds' atmospheres, revealing the characteristic trace of a unique and unknown molecule. It's unclear exactly what the molecule could be, and the mystery is made even more compelling by the fact that the environments of Pluto and Titan are very distinct.

Farther afield, the JWST's predecessor, the Hubble Space Telescope, spotted "impossible" light from a galaxy we shouldn't even be able to see. And in the busy skies surrounding our own planet, scientists are dreaming up a scheme to drop a giant "airbag" that could protect us from solar storms, sending spacecraft into orbit to save doomed telescopes, and also giving answers to why metal sticks together in space.

And just in time for Independence Day weekend, the sun has launched a string of eruptions to Earth that will likely paint the night skies with colorful auroras.

China's 'Great Green Wall' grows faster than natural forests

66 billion trees have been planted in China's Great Green Wall — and they appear to be growing faster than natural forests

China is no stranger to engineering projects designed to bring its environment to heel; we've recently covered the Asian powerhouse's attempts to tame nature through the creation of atmospheric rivers, the world's biggest dam and water transfers. But these are hardly China's only forays into sculpting its natural environment, with the country having planted more than 66 billion trees along its northern borders to halt the advance of the Gobi and Taklamakan deserts.

Now, new research has revealed a startling detail about the trees in this "Great Green Wall": they're growing significantly faster than natural forests. Exactly why remains a mystery, but, as Live Science contributor Brian Owens reveals, it could be due to a stronger response from the trees to rising atmospheric carbon dioxide.

Discover more planet Earth news

—'It sounds so impossible': Student studying fungus that makes users hallucinate tiny people may be on the verge of a scientific breakthrough

—'Uncharted territory': Record high ocean temperatures confirmed for June as El Niño strengthens its grip

—Study suggests life on Earth has around 1.8 billion years left — but the biosphere might evolve to survive even longer

Life's Little Mysteries

Are CAPTCHAs obsolete in the age of AI?

Are you a robot? It used to be a question that only humans could answer — by clicking on traffic lights or strings of warped and grainy characters, or Completely Automated Public Turing tests to tell Computers and Humans Apart (CAPTCHAs). But what happens now that autonomous artificial intelligence (AI) agents can ace some of these trials without detection? Have they made CAPTCHAs obsolete?

—If you enjoyed this, sign up for our Life's Little Mysteries newsletter

Medici murder mystery solved

Ancient-DNA analysis solves 500-year-old mystery of what killed 2 Medici brothers

The Medici family ruled Renaissance Tuscany with an iron fist, fulfilling their ruthless ambitions with methods so underhand that the name of their most famous advisor, Niccolò Machiavelli, became a synonym for skulduggery.

So, when two brothers from the infamous family died under mysterious circumstances, it was believed for 500 years that they were murdered, possibly by arsenic poisoning. Now, science has revealed the true culprit behind the medieval cold case, and it's not what we expected.

Discover more archaeology news

—Ancient ring discovered underground in Scotland could be a Stonehenge-like monument

—500-year-old freeze-dried potato snacks discovered in Inca storage room in Peru

—2,000-year-old scrolls buried by Mount Vesuvius eruption finally deciphered with help from AI

Also in science news this week

—Chinese supercomputer leapfrogs best US machines to be ranked world's fastest

—The hantavirus outbreak is over, WHO declares

—Rise in cancer in younger adults may be explained by faster 'biological aging,' early study hints

—Dead-end bitcoin mining wastes as much energy as Switzerland's entire hydropower generation capacity

—CERN shuts down Large Hadron Collider until 2030, upgrading the atom smasher to its most powerful form yet

—Scientists figured out how to shrink huge ultrafast lasers so they fit on a tiny chip ‪‪—‬ the 'holy grail' of the field

Science Spotlight

Japan's bold experiment to curb antibiotic misuse has been a huge success. Could it work in the US?

Antibiotic resistance is a growing threat in the U.S., with more than 2.8 million Americans developing antimicrobial-resistant infections each year. The solutions to this worrying trend can be very complex— such as moving agricultural systems away from their overreliance on antibiotics, or preventing the rapid spread of superbugs through international travel.

But stopping doctors from overprescribing antibiotics is one of the easiest strategies in the battle against this "silent pandemic." And it turns out that Japan has already fought it with some success, driving down antibiotic overuse with an innovative new policy. To investigate further and ask what notes the U.S. should be taking, Live Science's health editor Nicoletta Lanese visited Japan and reported back on their investigation.

Something for the weekend

If you're looking for things to keep you busy over the weekend, here are a smattering of our best expert opinion pieces, alongside a crossword, an interview and a quiz, that we published this week.

— Computer scientists are rushing to tame AI's voracious appetite for energy [Opinion]

—'It's more than a hope, it's a guarantee': The Vera C. Rubin Observatory's 10-year movie of the universe is about to 'blow our minds,' chief scientist Tony Tyson says [Interview]

—Live Science crossword puzzle #50: Longest-serving president in US history — 1 across [Crossword]

—Ancient empires quiz: Can you match these lands to the historical powers that ruled them? [Quiz]

Science photo of the week

Bull's-eye! Enormous 'bow and arrow' galaxy is unlike anything radio astronomers have ever seen

If you ask me, it looks more like a rusty anchor, or a blurry deep-sea fish. But whichever way you see it, the newly discovered "bow and arrow" galaxy — or, more formally, the RAD-Bow-And-Arrow Radio Galaxy (RAD-BAARG) — is an oddball unlike any other recorded.

The galaxy's unique structure is likely the result of gravity, which is warping RAD-BAARG into a funhouse mirror version of its former self as it falls into a nearby galaxy cluster. A shock front from this plunge surrounds the galaxy as it moves through hot gas.

Follow Live Science on social media

Want more science news? Follow our Live Science WhatsApp Channel for the latest discoveries as they happen. It's the best way to get our expert reporting on the go, but if you don't use WhatsApp we're also on Facebook, X (formerly Twitter), Flipboard, Instagram, TikTok, Bluesky and LinkedIn.

Fourth of July celebrations across the United States this weekend could be accompanied by light shows in the night skies, as a string of powerful solar eruptions appear set to strike Earth.

The sun has been especially hyperactive over the past few days — firing off 10 M-class solar flares over 24 hours that have been accompanied by multiple coronal mass ejections (CMEs), which are set to slam into Earth on July 3 and July 5.

CMEs are large, fast-moving clouds of magnetized plasma and solar radiation that occasionally get flung into space with solar flares when kinks in the sun's magnetic field snap. If CMEs smash into Earth, they cause disturbances in Earth's magnetic field, called geomagnetic storms, that can trigger partial radio blackouts and produce vibrant aurora displays farther away from Earth's magnetic poles than usual.

"Machine-Gun Sun! More than 5 storms on their way to Earth and 3 of them offer good chances for aurora views," Tamitha Skov, a space weather physicist at Millersville University of Pennsylvania, wrote in a July 2 post on the social platform X. "NOAA and NASA model predictions do not show all the storms yet (it's hard to keep up with the rapid-fire storm launches!) but the first should hit before noon July 3 UTC."

The CMEs are expected to give a glancing blow to our planet, creating conditions for a moderate (G2) geomagnetic storm, according to the National Oceanic and Atmospheric Administration's (NOAA) Space Weather Prediction Center. It's also possible that these storms will strengthen to become strong (G3), depending on how they interact with Earth's magnetic field.

Auroras resulting from G3-class geomagnetic storms are often visible in northern parts of Washington, Idaho, Montana, Wyoming, North Dakota, South Dakota, Minnesota, Wisconsin, Michigan, New York and Maine, according to NOAA. Skywatchers farther south in Oregon, Nebraska, Iowa, Illinois, Indiana, Ohio, Pennsylvania, Massachusetts, Connecticut, Rhode Island, Vermont and New Hampshire will also have a chance of catching the light show. In any case, skywatchers interested in seeing or photographing the auroras will need to get as far from artificial light sources as possible.

The weekend storms might not be the last activity we see from the sun in the coming days, as two gigantic sunspots currently pimpling its face are displaying "beta-gamma-delta" magnetic fields — the most tangled and unstable type. This means these sunspots harbor the potential to launch powerful X-class flares, according to spaceweather.com.

The last few years have seen a record number of powerful X-class flares explode from the sun's surface, hitting Earth with several major solar storms, including 2024's Mother's Day storm. This record comes partly from improvements to scientists' solar monitoring technologies, but also due to the sun reaching its 11-year peak in sunspot production, or solar maximum, in 2024.

Following this peak, the sun has now entered a period known as the "battle zone," a relatively understudied solar phase where instabilities across our star's newly flipped magnetic field ramp up the production of solar holes, gigantic, highly-tangled sunspots and subsequent geomagnetic storms.

The worst-case scenario for a solar storm is a superstorm like the 1859 Carrington Event, which released roughly the same energy as 10 billion 1-megaton atomic bombs. After slamming into Earth, the powerful stream of solar particles set telegraph systems around the world on fire and caused auroras brighter than the light of the full moon to appear as far south as the Caribbean.

The Carrington Event unleashed a roughly X45 magnitude solar flare that remains a record, yet it's likely far from the worst the sun can muster — with ancient tree rings harboring evidence of even more powerful blasts that occurred long before humans existed.

The hantavirus outbreak that struck a cruise ship in April, killing three people and sparking fears of further spread, is over, the World Health Organization (WHO) has announced.

"Today, the final contact of a person exposed to hantavirus on the cruise ship MV Hondius completed their quarantine period, tested negative and returned home. No further cases have been reported since the 25th of May," Tedros Adhanom Ghebreyesus, the WHO's director-general, said in his opening remarks at a news conference Thursday (July 2). "We are therefore very pleased to say that WHO considers the outbreak of hantavirus over."

The total number of cases linked to the outbreak was 13. All those affected were either passengers or crew on the ship.

The outbreak began aboard the Dutch-flagged cruise ship MV Hondius after it departed southern Argentina on April 1. It involved the Andes virus, the only known hantavirus that can spread between people.

Hantaviruses are rodent-borne viruses that are found in the Americas, Europe and Asia and spread to humans relatively rarely, usually via contact with the urine, droppings or saliva of infected rodents. The Andes virus, however, has sparked short chains of human-to-human transmission in the past.

Before public health authorities were informed of the cases on MV Hondius, several dozen people disembarked the vessel on the island of St. Helena. To find them, authorities launched an international contact-tracing operation, tracking down more than 650 contacts in total who were then followed by health authorities in 33 countries and territories, according to the WHO.

Additionally, health authorities coordinated the monitoring, care and transport of the remaining passengers and crew aboard MV Hondius.

Of these contacts, those considered at the highest risk of infection were then quarantined and monitored for up to 42 days, because sometimes, hantavirus symptoms don't show up until weeks after exposure to the virus. Depending on their jurisdiction and degree of exposure, some contacts quarantined at home while others stayed in specialized facilities.

The initial unchecked travel of some contacts, alongside the virus's long incubation period, prompted concern from the public that the cluster of cases could explode into an enormous outbreak, or even a global pandemic. Many infectious-disease experts emphasized that the Andes virus does not spread easily between people and that the containment effort was going well, so the risk of a large outbreak was low. Still, some experts raised concerns that the international travel of contacts could trigger pockets of the deadly disease, and some argued that the Andes virus does have "pandemic potential."

Now, with the final contact having completed their quarantine period and no further cases reported, the WHO has declared the outbreak over. All of the contacts who were repatriated to the U.S. completed their quarantine period by June 21.

"WHO will continue working with governments and partners to advance our understanding of this outbreak and of hantavirus more generally," Tedros said. "We are also coordinating a study involving 21 countries to understand how the disease develops, which will support the development of diagnostics, therapeutics and vaccines for future outbreaks."

Besides rigorous contact tracing, the WHO credited the coordinated actions of national public health bodies as being vital to preventing the further spread of the disease. These measures included the response of the Spanish government, which created a safe zone on the island of Tenerife for the ship's remaining passengers to disembark before they were repatriated under quarantine.

As the hantavirus outbreak concludes, there's an ongoing Ebola outbreak in the Democratic Republic of the Congo and an outbreak of the Marburg virus in Uganda. These and future outbreaks will require similarly robust international cooperation, the WHO emphasized.

"The outbreaks of hantavirus, Ebola and Marburg all show why there is no alternative to international cooperation in the face of international threats," Tedros said. "No country alone can fight."

This article is for informational purposes only and is not meant to offer medical advice.