The newly confirmed planets, TOI-791 b and TOI-791 c, orbit an F7-type dwarf star about 1,110 light years from Earth in the southern constellation Volans. Although each planet is about the size of Jupiter, both are remarkably lightweight for their size.

TOI-791 b has a density of just 0.038 grams per cubic centimeter, while TOI-791 c measures 0.047 grams per cubic centimeter. Jupiter, by comparison, has an average density of 1.33 grams per cubic centimeter, making it roughly 28 to 35 times denser than these newly discovered worlds.

The comparison becomes even more striking when measured against candy floss, which has a typical density of about 0.05 grams per cubic centimeter. Earth is much denser still, averaging 5.5 grams per cubic centimeter.

Rare Planetary Twins Locked in a Gravitational Dance

Scientists believe the two planets formed together from the same disc of gas and dust surrounding their young star, making them planetary “siblings.”

They are also linked by an unusual orbital arrangement called a 5:3 mean-motion resonance. For every five orbits completed by the inner planet, the outer planet finishes almost exactly three. As they circle their star, their gravity repeatedly pulls on one another, creating small but measurable changes in the timing of each planet’s transit.

Only four other planetary systems are known to contain multiple super-puff planets, making TOI-791 an exceptionally rare opportunity to investigate how these unusual worlds originate and evolve.

Lead author Dr. George Dransfield (she/her) (Department of Physics, University of Oxford and a presenter for BBC Sky at Night) said:

“Only a handful of these super-puffy planets are known, and it is even rarer to find two in the same system. Their extremely low densities make them fascinating targets for understanding how planetary systems form and evolve.”

Citizen Scientists Helped Find the Planets

Volunteers participating in the Planet Hunters TESS citizen-science project first flagged TOI-791 b in 2019 and TOI-791 c in 2023 as possible planets. The project searches observations collected by NASA’s Transiting Exoplanet Survey Satellite (TESS) for signs of previously unknown worlds.

Researchers then combined measurements from telescopes around the world to determine the planets’ sizes and masses, allowing them to calculate their exceptionally low densities.

When a planet crosses in front of its star during a “transit,” it blocks a small amount of starlight. That dip in brightness reveals the planet’s size. In the TOI-791 system, astronomers also detected tiny changes in the timing of the transits caused by the planets’ gravitational interactions. Analyzing those timing variations allowed the team to estimate each planet’s mass.

Antarctica Played a Key Role

The discovery was built on eight years of observations, including data from the ASTEP (Antarctic Search for Transiting ExoPlanets) telescope at Concordia Station in Antarctica. The telescope is jointly operated by researchers from Université Côte d’Azur/Observatoire de la Côte d’Azur and international collaborators.

Antarctica’s long winter nights gave astronomers a major advantage. Months of uninterrupted darkness made it possible to observe the planets’ unusually long transits, each lasting more than 11 hours, without interruption. According to the researchers, these are the longest continuous planetary transits ever fully observed from the ground.

How Do Super-Puff Planets Form?

Scientists are still trying to understand how super-puff planets develop.

One leading explanation is that these worlds possess enormous atmospheres rich in hydrogen and helium that account for a large fraction of their total mass. Researchers think these thick gaseous envelopes may have formed when the planets were much farther from their star, in colder regions of the protoplanetary disc where gas could rapidly accumulate around a solid planetary core.

Future observations are planned to better understand the origins of these unusual planets and test competing theories.

Professor Amaury Triaud (University of Birmingham), the UK Principal Investigator of ASTEP and co-author of the study, said:

“This system offers a unique laboratory for understanding how super-puff planets form and evolve. We propose to carry out space-based observations using the James Webb Space Telescope to assess if the puffy atmosphere contains carbon-, nitrogen-, and oxygen-bearing species, revealing new insight into how these unusual planets formed.”

Professor Tristan Guillot (Université Côte d’Azur), Principal Investigator of ASTEP and co-author of the study, added:

“These multi-planetary systems are complex, with gravitational interactions between the planets that evolve over very long periods, tens of years or more. This discovery highlights the importance of continued international collaboration in astronomy. Bringing together observations from Antarctica, space telescopes and observatories across several continents was essential to revealing the true nature of these extraordinary planets.”

Researchers at Kyushu University have now created a solid-state molecular material capable of converting visible sunlight into ultraviolet (UV) light under normal outdoor conditions. The new material achieves a photo upconversion efficiency of 1.9%, according to a study published June 23 in Nature Communications.

Why UV Light Matters

Although many people associate UV light with sunburns and skin damage, it plays an important role in numerous technologies. UV light is used for air purification, curing resins in 3D printing, hardening gels in dental fillings, and even applications such as nail treatments.

Despite its usefulness, UV light represents only about 6% of the sunlight that reaches Earth’s surface. Even then, only part of that UV radiation is practical for technological applications.

“What we do here is ‘add together’ the energy from two visible light photons to make one ultraviolet photon. It’s a fascinating process called photo upconversion,” explains Yoichi Sasaki, Associate Professor at Kyushu University’s Faculty of Engineering and the study’s corresponding author.

Turning Visible Light Into UV Light

The process relies on a phenomenon known as triplet-triplet annihilation (TTA). In this approach, a molecule known as a donor absorbs visible light and enters a high-energy triplet state. That energy is then transferred to a nearby acceptor molecule.

When two triplet states encounter one another, they combine and release their energy as a single UV photon.

Scientists have long known that TTA works effectively in liquids because molecules can move freely and interact easily. However, liquid systems often require toxic solvents and may evaporate over time, limiting their practicality. As a result, researchers have spent years searching for a reliable solid-state alternative.

“In solids, molecules are packed tightly, and the π electron clouds — regions of high electron density hovering above and below each molecular plane — can overlap,” says Sasaki. “When that happens, triplets easily fizzle out before they ever meet. Molecules must be close enough for energy to transfer but separated enough to prevent quenching of excitons.”

A New Solid-State Solution

The team’s breakthrough came from an organic semiconductor called dihydroindenoindenedene (DHI).

The researchers modified DHI by attaching alkyl chains to its sp³ carbon atoms — which have four bonds pointing in fixed 3D directions. This design created carefully controlled spacing between neighboring molecules. The molecules remained close enough to transfer energy efficiently while avoiding the strong electronic interactions that can suppress performance.

The resulting material exhibited strong luminescence, long-lived excited states, and highly effective energy transfer. It achieved a solid-state fluorescence quantum yield greater than 60%.

When paired with a donor molecule, the system reached an upconversion efficiency of 1.9%.

“This means roughly two UV photons are produced for every hundred visible-light photons absorbed,” Sasaki adds. “It may sound low, but it runs on natural sunlight alone. Most solid-state materials cannot realize this even at much higher light intensity.”

Potential Applications for Solar-Powered UV Light

The researchers have filed a patent application for the material.

In addition to its performance, the material offers practical advantages. It can be synthesized relatively easily and is made from inexpensive starting materials. The team believes it could eventually be used in solar-powered photocatalysis, indoor air purification systems, and low-intensity 3D printing technologies.

A 14-Year Scientific Journey

For the researchers involved, the achievement represents more than a technical advance.

In 2012, Nobuo Kimizuka, now Professor Emeritus at Kyushu University’s Research Center for Negative Emissions Technologies, began exploring photon upconversion through triplet energy migration in self-assembled molecular systems. His goal was to establish a form of molecular systems chemistry in which self-assembly could perform useful functions.

Over the following years, his group made steady progress using solution-based and gel-based systems. Efficient solid-state upconversion, however, remained difficult to achieve.

A major breakthrough finally arrived in May 2024, less than a year before Kimizuka’s retirement.

The months that followed became an intense push to bring the project to completion. Graduate students Naoyuki Harada, Hayato Shoyama, and Nutnicha Boonmong worked alongside Sasaki and then-Assistant Professor Kiichi Mizukami of Kyushu University’s Faculty of Engineering to consolidate years of research into a final publication.

“We handed the draft to Professor Kimizuka just 11 days before he left the lab, which for us felt like a heartfelt retirement gift,” Sasaki notes.

“This discovery is the culmination of over 14 years of our research and marks a major milestone in photon-upconversion and molecular self-assembly research,” concludes Kimizuka.

Scientists at the Monell Chemical Senses Center discovered that fructose and glucose communicate with the brain through separate gut-brain pathways. Their findings indicate that these differences may influence food and beverage preferences and could help explain why certain sweetened products are especially appealing.

The study, published June 10 in the journal Neuron, identified a specific signaling route that allows fructose to communicate with the brain. In experiments involving mice, researchers found that this pathway was far less effective than the one used by glucose when it came to reducing activity in neurons associated with hunger.

“This work adds to our growing understanding of how modern diets, especially those high in fructose or high-fructose corn syrup, interact with the neural systems involved in appetite,” said senior author and Monell Member Amber Alhadeff, PhD.

How Fructose and Glucose Affect Hunger Neurons

To investigate how the sugars influence the brain, researchers recorded neural activity in mice after exposure to fructose and glucose.

The team found that fructose increased levels of the gut hormone PYY. That hormone then signaled through the vagus nerve, leading to a modest reduction in the activity of agouti-related protein (AgRP) neurons, which play a major role in driving hunger. When researchers disrupted this pathway, fructose could no longer affect those neurons.

Glucose produced a very different response. According to the researchers, it did not rely on the same PYY-Y2 vagus nerve pathway. Instead, glucose strongly suppressed AgRP neuron activity, resulting in a much larger effect on hunger-related brain signaling.

Sugar Type Influenced Food Preferences

Although fructose and glucose produced similar short-term effects on food intake, the mice eventually developed preferences that corresponded to the degree of AgRP neuron inhibition triggered by each sugar.

The researchers also examined high-fructose corn syrup (HFCS), a widely used sweetener made from a combination of fructose and glucose. The mice showed a preference for HFCS, and the sweetener suppressed AgRP neuron activity more strongly than fructose alone.

According to the researchers, this stronger effect on hunger-related neurons may help explain why foods and beverages containing HFCS can be particularly appealing.

Challenging Assumptions About Calories and Hunger

The results call into question a long-held assumption that AgRP neurons primarily track calorie intake regardless of where those calories come from.

Instead, the findings suggest that these hunger-related neurons can distinguish between different sugars and respond through separate biological pathways. Even though fructose and glucose provide the same amount of energy, the mice’s brains processed them differently.

The study highlights the complexity of nutrient sensing in the body and suggests that even simple sugars can have distinct effects on the gut, the brain, and behavior.

This research was supported by grants R01DK131558, DP2AT011965, R01DK116004, F31DK13558, and S10OD030354 from the National Institutes of Health; the American Heart Association; the New York Stem Cell Foundation; the Klingenstein Fund; the Simons Foundation, the Pew Charitable Trusts, the Penn Institute for Diabetes, Obesity, and Metabolism; the Hearst Fellowship, and the Monell Chemical Senses Center.

A recent study presented at the 2026 Lunar and Planetary Science Conference (LPSC) takes a closer look at that possibility. Researchers from The Johns Hopkins University Applied Physics Laboratory (JHUAPL) and Sandia National Laboratories used the “Venus Life Equation” (VLE), a framework developed by Noam Izenberg et al. in 2021, to estimate how material from Earth could introduce life into Venus’ atmosphere. Their modeling suggests that life delivered from Earth could potentially survive in Venus’ clouds for at least a few days per century.

The Venus Life Equation

Like the famous Drake Equation, the VLE estimates the probability of life by combining several contributing factors. Each factor is multiplied together to produce an overall estimate of the likelihood that life exists.

*### L = O x R x C*

In this equation, L represents the likelihood of Extant Life (0 to 1, where 0 is no chance and 1 is certainty). O stands for origination (the chance life began and became established on Venus), R represents Robustness (the ability of a biosphere to survive and adapt to changing conditions), and C refers to Continuity (The chance that habitable conditions persisted until today). Before applying this framework, the researchers first examined whether organic material could survive the journey from one planet to another, regardless of where it originally formed.

Surviving the Journey to Venus

Material blasted into space by an impact must endure enormous challenges. In addition to the violent shock of ejection, it is exposed to intense heat, the vacuum of space, radiation, and extreme temperature swings. Previous computer simulations and analyses of meteorites found on Earth have shown that organic material can survive both ejection from a planet and the trip through interplanetary space. Once it reaches Venus, however, that material would also need to remain suspended within or above the planet’s cloud layers in order to survive.

To investigate this, the team modeled how fireball meteorites (bolides) behave as they enter Venus’ atmosphere, including their ablation, explosion, and breakup into smaller fragments capable of remaining in the clouds. They relied on the “pancake model,” a widely used semi-analytic approach that describes how a bolide fragments while passing through an atmosphere. After the bolide explodes in the atmosphere (an “airburst”), aerodynamic drag spreads the fragments outward into a flattened “pancake” of material that the researchers describe as “cells.”

Billions of Potential Transfers

Using the pancake model together with values derived from earlier studies, the researchers estimated how many bolides from Earth or Mars could have reached Venus’ clouds. Their calculations suggest that hundreds of billions of cells may have been delivered from Earth to Venus, with hundreds of billions potentially remaining viable. Their preferred estimate indicates that about 100 cells become dispersed throughout Venus’ clouds each Earth year. Over the past 1 billion years, roughly 20 billion cells may have been transferred from Earth.

The researchers emphasize that their model does not capture every aspect of how bolides interact with Venus’ atmosphere. They also note that every parameter in the VLE carries significant uncertainty, much like the Drake Equation. Even so, their findings support the possibility that panspermia between Earth and Venus could occur. If a future astrobiology mission discovers life in Venus’ clouds, one possible explanation is that it originally came from Earth.

On July 2, 2025, the China-led Einstein Probe (EP) space telescope spotted an exceptionally bright X-ray source during a routine survey of the sky. The object’s brightness changed rapidly, making it immediately stand out from typical cosmic X-ray sources. The unusual detection prompted observatories around the world to begin follow-up observations.

The research was coordinated by the EP Science Center at the National Astronomical Observatories, Chinese Academy of Sciences (NAOC), with scientists from research institutions in China and several other countries contributing to the effort. Researchers from the Department of Physics at The University of Hong Kong (HKU), who are key members of the Einstein Probe scientific collaboration, helped interpret the observations. Their analysis suggests the event may represent an intermediate-mass black hole tearing apart and consuming a white dwarf star. If confirmed, it would provide the first direct observational evidence of this type of black hole feeding event. The results were published as the cover article in Science Bulletin.

Einstein Probe Detects an Unusual Cosmic Explosion

The discovery relied on the Einstein Probe’s two complementary X-ray instruments.

During its routine survey on July 2, 2025, the mission’s Wide-field X-ray Telescope (WXT), which combines advanced lobster-eye micro-pore optics with a very wide field of view and high sensitivity, detected a rapidly changing X-ray source that was later designated EP250702a (also known as GRB 250702B). At nearly the same time, NASA’s Fermi Gamma-ray Space Telescope detected several gamma-ray bursts coming from the same region of the sky.

Scientists realized the event was far more unusual after reviewing earlier WXT observations. The telescope had already detected steady X-ray emission from the same location roughly a day before the gamma-ray bursts appeared, a sequence rarely associated with powerful cosmic explosions. Around 15 hours after the initial detection, the source erupted into a series of intense X-ray flares. At its brightest, it reached a luminosity of approximately 3 × 10⁴⁹ erg s^-1, making it one of the brightest instantaneous outbursts ever recorded in the Universe.

“This early X-ray signal is crucial,” said Dr. Dongyue Li, first author of the paper from the National Astronomical Observatories of China. “It tells us this was not an ordinary gamma-ray burst.”

Rare X-Ray Signal Points to a Black Hole Feeding Event

Using the precise location measured by WXT, astronomers quickly directed major telescopes around the world toward the source. Observations across multiple wavelengths confirmed that the object was located on the outskirts of a distant galaxy. The Einstein Probe’s second instrument, the Follow-up X-ray Telescope (FXT), then monitored the event as it evolved.

Over roughly 20 days, the object’s brightness faded by more than a factor of 100,000. During that time, its X-ray emission also shifted from higher-energy (“hard”) X-rays to lower-energy (“soft”) X-rays.

After combining Einstein Probe observations with data collected across the electromagnetic spectrum, researchers found that EP250702a displayed several characteristics that existing models struggled to explain. Its X-ray emission began before the gamma-ray burst, it reached extraordinary brightness, evolved unusually quickly, and occurred in the outer region of its host galaxy instead of near the galaxy’s center, a combination that is rarely seen in known high-energy cosmic events. After evaluating multiple possible explanations, one scenario emerged as the strongest candidate: an intermediate-mass black hole tearing apart and consuming a white dwarf star.