Category: 7. Science

In recent days, you may have seen articles claiming the “best meteor shower of the year” is about to start. Unfortunately, the hype is overblown – particularly for observers in Australia and New Zealand.

The shower in question is the Perseids, one of the “big three” – the strongest annual meteor showers. Peaking in the middle of the northern summer, the Perseids are an annual highlight for observers in the northern hemisphere.

As a result, every year social media around the world runs rife with stories about how we can enjoy the show. For an astronomer in Australia, this is endlessly frustrating – the Perseids are impossible to see for the great majority of Australians and Kiwis.

Fortunately, there are a few other meteor showers to fill the void, including a pair that will reach their peak in the next seven days.

What are the Perseids?

Every year, Earth runs into a stream of debris laid down over thousands of years by comet 109P/Swift–Tuttle. The comet swings around the Sun every 133 years or so, shedding dust and debris each time. Over the millenia, that material has spread to create a vast stream.

Earth starts to run into debris from Swift–Tuttle in mid-July, and takes six weeks to pass through the stream. When the dust and debris hit Earth’s atmosphere, the resulting meteors create bright streaks in the sky – a meteor shower.

For most of that time, the dust we encounter is very widely spread, and so few meteors are seen. Around August 12, Earth reaches the densest part of the Perseid stream and the shower reaches its peak.

The Perseids aren’t even the ‘best’ meteor shower

Comet Swift–Tuttle last passed through the inner Solar System in 1992. With the comet nearby, Earth encountered more dust and debris, making the Perseids the best meteor shower of the year.

In the decades since, the comet has receded to the icy depths of the Solar System, and the peak rates for the Perseids have fallen off.

The “best” (most abundant) meteor shower of the year is now the Geminids. However, for people in the northern hemisphere, the Perseids are still well worth looking out for.

The curse of the spherical Earth

All meteor showers have a “radiant”– the point at which meteors seem to originate in the sky. This is because, for a given shower, all the debris hitting Earth comes from the same direction in space.

The debris from comet Swift–Tuttle crashes towards Earth from above the north pole, and at an angle. As a result, for people at a latitude of 58 degrees north, the Perseid radiant would be directly overhead in the early hours of the morning.

If a meteor shower’s radiant is below the horizon, you won’t see any meteors – Earth is in the way, and all the dust and debris is hitting the other side of the planet. It’s exactly the same reason you can’t see the Sun at nighttime.

Given the location of the Perseid radiant, it will never rise for observers south of 32 degrees. This means anyone below that line will never see any Perseids.

In theory, anyone north of 32 degrees south latitude can see the Perseids – but there are other complications.

The higher a shower’s radiant is in the sky, the more meteors you will see. This is why the Perseids can’t put on a great show for people in Australia. Even in the far north of Australia, the Perseid radiant remains low in the sky at its highest. For most Australians, the Perseids will be a spectacular disappointment.

Look for these meteor showers instead

If you’re keen to see a meteor shower from Australia or New Zealand, it’s best to cross the Perseids off your list. Fortunately, there are other options.

Every May, Earth passes through debris left behind by comet 1P/Halley, creating the Eta Aquariid meteor shower – only visible in the hours before dawn. For Australian observers, that’s the second best shower of the year.

At the end of July each year, two minor meteor showers reach their peaks: the Southern Delta Aquariids and Alpha Capricornids. This year, they peak on 29 and 30 July, with the best views coming in the hours around midnight. It’s a perfect time to head out to a dark sky site and relax under the stars – the centre of the Milky Way is high overhead in the evening sky, and these two showers provide some added fireworks to make the sky extra special.

Then, in December, comes the true “best shower of the year” – the Geminids. Reaching a peak on 14 and 15 December, the Geminids always put on a spectacular show. Unlike the Perseids, it can be seen from all across our island continent and in Aotearoa.

If you really want to see a great meteor shower, skip the Perseids and plan to head somewhere dark this summer, to spend a couple of nights relaxing under the stars.

PARIS: Since at least the time of the ancient Egyptians, people across the world have gazed up in awe at Betelgeuse, one of the brightest stars blazing in the night sky.

Now astronomers have discovered that this red supergiant, known to many as the hunter’s shoulder in the Orion constellation, is being orbited by a much smaller companion star, a study said on Monday. It is not the first time Betelgeuse has surprised stargazers.

Seemingly out of nowhere, the giant star dramatically dimmed for five months between 2019 and 2020, leading some scientists to suggest it could soon die in an epic supernova explosion.

Further observations revealed that this event — known as the “Great Dimming” — was actually caused by material ejected from the surface that cooled part of the star, creating a dust cloud that blocked its light. But scientists could still not explain why Betelgeuse’s brightness changes regularly, both on a 400-day cycle and another that lasts nearly six years.

In a paper titled “A Buddy for Betelgeuse” published in December, some researchers theorised that the longer variation could be caused by a hidden small star orbiting the behemoth. Astronomers using the Gemini North telescope in Hawaii have now discovered this elusive companion, according to a new study in The Astrophysical Journal Letters.

This companion has a mass around 1.5 times greater than our Sun, the research estimated. That means it is dwarfed by Betelgeuse, which is 1,000 times bigger than the Sun.

The companion star is around four times the distance from Betelgeuse as the Earth is from the Sun, which is quite close for a stellar companion.

Published in Dawn, July 22nd, 2025

A short-lived heat wave that hit the Los Angeles area the week of July 7, 2025, was the first of summer. The heat lingered into the evening hours, as captured by NASA’s Ecosystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) instrument.

By nearly 8:45 p.m. local time July 9, surface temperatures in the San Fernando Valley were still over 80 degrees Fahrenheit (27 degrees Celsius). The ECOSTRESS sensor recorded similar temperatures for downtown Pasadena (Figure A) and parts of Altadena, east of NASA’s Jet Propulsion Laboratory, which manages the mission. In these data visualizations, dark red indicates higher temperatures, while areas in blue and green are cooler. Coastal regions remained significantly cooler than inland areas.

The ECOSTRESS instrument measures thermal infrared emissions from Earth’s surface. This enables researchers to monitor plant health, the progress of wildfires, land surface temperatures, and the burn risk to people from hot surfaces such as asphalt. Land surface temperatures are hotter than air temperatures during the day. Air temperatures, which are measured out of direct sunlight, are usually what meteorologists report in a weather forecast.

The instrument launched to the space station in 2018. Its primary mission is to identify plants’ thresholds for water use and water stress, giving insight into their ability to adapt to a warming climate. NASA’s Jet Propulsion Laboratory in Southern California built and manages the ECOSTRESS mission for the Earth Science Division in the Science Mission Directorate at NASA Headquarters in Washington. ECOSTRESS is an Earth Venture Instrument mission; the program is managed by NASA’s Earth System Science Pathfinder program at NASA’s Langley Research Center in Hampton, Virginia.

More information about ECOSTRESS is available here:

https://ecostress.jpl.nasa.gov/.

SpaceX aborted the launch of two communications satellites just before liftoff on Monday evening (July 21).

A Falcon 9 rocket topped with two of SES’ O3b mPOWER internet spacecraft was set to launch from Florida’s Cape Canaveral Space Force Station at 5:27 p.m. EDT (2127 GMT) on Monday.

For more than a century, physicists have relied on two separate rulebooks to describe nature. Quantum mechanics excels at explaining atoms, photons, and every jiggle inside laboratories. Einstein’s general relativity, meanwhile, accounts for the way planets and stars bend the very fabric of space-time.

Each framework is staggeringly accurate inside its own arena, yet they cannot be combined in a single equation.

Closing that rift has been a dream project for generations. Now a fresh proposal points to an unexpectedly practical route: link a trio of ultrafine atomic clocks with the same quantum technology that will one day support a globe-spanning quantum internet, then scatter those clocks along the side of a mountain.

If everything works, the experiment will watch quantum superpositions ride Earth’s curved space-time and reveal whether the two great theories can truly coexist.

Quantum clocks on the hillside

The idea comes from Igor Pikovski at Stevens Institute of Technology, Jacob Covey at the University of Illinois Urbana-Champaign, and Johannes Borregaard at Harvard University.

Their paper, “Probing Curved Spacetime with a Distributed Atomic Processor Clock,” just published in PRX Quantum, lays out a detailed plan to marry quantum networking with precision metrology.

“The interplay between quantum theory and gravity is one of the most challenging problems in physics today, but also fascinating,” says Pikovski. “Quantum networks will help us test this interplay for the first time in actual experiments.”

The team’s blueprint treats a mountain slope as a ready-made laboratory, using natural height differences to amplify the tiny time shifts predicted by relativity.

Atomic clocks as quantum probes

Atomic clocks already underpin GPS satellites and global timekeeping because they lose only a second every billion years. Each tick comes from the regular light absorbed and emitted by atoms such as ytterbium-171.

In the new scheme, three such clocks sit at elevations separated by hundreds of feet – enough for gravity to make the topmost clock run a hair faster than the one at the base.

Because the clocks are quantum devices, they can be placed in superposition, meaning they effectively tick in several places at once.

Physicists have already confirmed gravitational time dilation with aircraft and satellites, but those tests rely on classical synchronization.

Using a truly quantum clock raises the bar by letting the same single tick sample multiple altitudes at once, squeezing uncertainty far below the part-per-quadrillion level.

Entanglement as the secret sauce

To keep the trio operating as one coherent device, the researchers rely on a highly resilient entangled W-state.

Only one of the three nodes carries the active “excitation,” yet all share responsibility for it. If one station suffers a hiccup, the overall state survives, a feature prized in quantum communication.

Entanglement also enables quantum teleportation of timing information, letting the scientists recombine the separated pieces without physically hauling hardware up and down the slope.

Network links often rely on photons coursing through buried fiber or free-space laser connections. Either route can ferry entanglement over miles, as recent field trials between Chicago and Boston have shown.

The mountainside layout taps that same infrastructure, so every tweak made for the gravity test feeds directly back into the playbook for tomorrow’s secure data highways.

Following quantum clock beats

As the entangled clock ticks, each node accumulates a slightly different phase because the local flow of time is not identical.

When those phases are brought back together through teleportation, the interference pattern should display three distinct beat notes.

Their spacing encodes the altitude differences measured in feet as well as the combined effect of quantum superposition and curved space-time.

If either theory – quantum mechanics or general relativity – fails to describe reality at this overlap, the rhythm will stray from expectations.

Counting those beat notes requires detectors that resolve differences smaller than a billionth of a second. Modern frequency combs let researchers compare optical clock signals with that level of finesse, turning what once seemed a sci-fi feat into standard lab practice.

Finding terra firma

Beyond a proof of principle, the test would put long-standing speculations on firmer footing.

“We assume that quantum theory holds everywhere – but we really don’t know if this is true,” says Pikovski.

“It might be that gravity changes how quantum mechanics works. In fact, some theories suggest such modifications, and quantum technology will be able to test that.”

A measurable deviation might hint at new physics, while a perfect match would still tighten the bounds on any would-be quantum-gravity adjustment by orders of magnitude.

Quantum internet with benefits

Tools developed for the curved-space-time experiment mirror the hardware racing toward a secure quantum internet.

Entangled Bell pairs, teleportation channels, and error-tolerant W-states are exactly what future data links will need to move qubits between city-scale processors.

By turning those same tricks to fundamental research, the community gains a double dividend: technology gets a demanding field test, and basic science gains reach far beyond a conventional lab bench.

Organizations planning intercity quantum links already mount repeaters on towers and rooftops, where elevation shifts come for free.

Embedding fundamental tests into those rollouts might transform mundane network maintenance into a new branch of precision geodesy.

Quantum clocks and future tech

Building the network will still be an engineering lift. Optical fibers must carry entanglement hundreds of feet with minimal loss, while laser systems keep the ytterbium atoms chilled to microkelvin temperatures.

Yet none of those tasks lie outside today’s state of the art.

If the experiment runs and the beats line up with theory, physicists will have brought two rival descriptions of the universe a little closer together.

And if the beats slip, an even bigger adventure will begin – one that may finally show how quantum science and gravity influence each other.

Either result – agreement or surprise – will refine blueprints for space-based missions aiming to stretch entangled clocks between satellites.

Those projects could bring the same test into stronger gravitational gradients near massive bodies, extending the quest well beyond any earthly mountain ridge.

The full study was published in the journal Physical Review.

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Earth is spinning faster this summer, making the days marginally shorter and attracting the attention of scientists and timekeepers.

July 10 was the shortest day of the year so far, lasting 1.36 milliseconds less than 24 hours, according to data from the International Earth Rotation and Reference Systems Service and the US Naval Observatory, compiled by timeanddate.com. More exceptionally short days are coming on July 22 and August 5, currently predicted to be 1.34 and 1.25 milliseconds shorter than 24 hours, respectively.

The length of a day is the time it takes for the planet to complete one full rotation on its axis —24 hours or 86,400 seconds on average. But in reality, each rotation is slightly irregular due to a variety of factors, such as the gravitational pull of the moon, seasonal changes in the atmosphere and the influence of Earth’s liquid core. As a result, a full rotation usually takes slightly less or slightly more than 86,400 seconds — a discrepancy of just milliseconds that doesn’t have any obvious effect on everyday life.

However these discrepancies can, in the long run, affect computers, satellites and telecommunications, which is why even the smallest time deviations are tracked using atomic clocks, which were introduced in 1955. Some experts believe this could lead to a scenario similar to the Y2K problem, which threatened to bring modern civilization to a halt.

Atomic clocks count the oscillations of atoms held in a vacuum chamber within the clock itself to calculate 24 hours to the utmost degree of precision. We call the resulting time UTC, or Coordinated Universal Time, which is based on around 450 atomic clocks and is the global standard for timekeeping, as well as the time to which all our phones and computers are set.

Astronomers also keep track of Earth’s rotation — using satellites that check the position of the planet relative to fixed stars, for example — and can detect minute differences between the atomic clocks’ time and the amount of time it actually takes Earth to complete a full rotation. Last year, on July 5, 2024, Earth experienced the shortest day ever recorded since the advent of the atomic clock 65 years ago, at 1.66 milliseconds less than 24 hours.

“We’ve been on a trend toward slightly faster days since 1972,” said Duncan Agnew, a professor emeritus of geophysics at the Scripps Institution of Oceanography and a research geophysicist at the University of California, San Diego. “But there are fluctuations. It’s like watching the stock market, really. There are long-term trends, and then there are peaks and falls.”

In 1972, after decades of rotating relatively slowly, Earth’s spin had accumulated such a delay relative to atomic time that the International Earth Rotation and Reference Systems Service mandated the addition of a “leap second” to the UTC. This is similar to the leap year, which adds an extra day to February every four years to account for the discrepancy between the Gregorian calendar and the time it takes Earth to complete one orbit around the sun.

Since 1972, a total of 27 leap seconds have been added to the UTC, but the rate of addition has increasingly slowed, due to Earth speeding up; nine leap seconds were added throughout the 1970s while no new leap seconds have been added since 2016.

In 2022, the General Conference on Weights and Measures (CGPM) voted to retire the leap second by 2035, meaning we may never see another one added to the clocks. But if Earth keeps spinning faster for several more years, according to Agnew, eventually one second might need to be removed from the UTC. “There’s never been a negative leap second,” he said, “but the probability of having one between now and 2035 is about 40%.”

What is causing Earth to spin faster?

The shortest-term changes in Earth’s rotation, Agnew said, come from the moon and the tides, which make it spin slower when the satellite is over the equator and faster when it’s at higher or lower altitudes. This effect compounds with the fact that during the summer Earth naturally spins faster — the result of the atmosphere itself slowing down due to seasonal changes, such as the jet stream moving north or south; the laws of physics dictate that the overall angular momentum of Earth and its atmosphere must remain constant, so the rotation speed lost by the atmosphere is picked up by the planet itself. Similarly, for the past 50 years Earth’s liquid core has also been slowing down, with the solid Earth around it speeding up.

By looking at the combination of these effects, scientists can predict if an upcoming day could be particularly short. “These fluctuations have short-period correlations, which means that if Earth is speeding up on one day, it tends to be speeding up the next day, too,” said Judah Levine, a physicist and a fellow of the National Institute of Standards and Technology in the time and frequency division. “But that correlation disappears as you go to longer and longer intervals. And when you get to a year, the prediction becomes quite uncertain. In fact, the International Earth Rotation and Reference Systems Service doesn’t predict further in advance than a year.”

While one short day doesn’t make any difference, Levine said, the recent trend of shorter days is increasing the possibility of a negative leap second. “When the leap second system was defined in 1972, nobody ever really thought that the negative second would ever happen,” he noted. “It was just something that was put into the standard because you had to do it for completeness. Everybody assumed that only positive leap seconds would ever be needed, but now the shortening of the days makes (negative leap seconds) in danger of happening, so to speak.”

The prospect of a negative leap second raises concerns because there are still ongoing problems with positive leap seconds after 50 years, explained Levine. “There are still places that do it wrong or do it at the wrong time, or do it (with) the wrong number, and so on. And that’s with a positive leap second, which has been done over and over. There’s a much greater concern about the negative leap second, because it’s never been tested, never been tried.”

Because so many fundamental technologies systems rely on clocks and time to function, such as telecommunications, financial transactions, electric grids and GPS satellites just to name a few, the advent of the negative leap second is, according to Levine, somewhat akin to the Y2K problem — the moment at the turn of the last century when the world thought a kind of doomsday would ensue because computers might have been unable to negotiate the new date format, going from ’99’ to ’00.’

The role of melting ice

Climate change is also a contributing factor to the issue of the leap second, but in a surprising way. While global warming has had considerable negative impacts on Earth, when it comes to our timekeeping, it has served to counteract the forces that are speeding up Earth’s spin. A study published last year by Agnew in the journal Nature details how ice melting in Antarctica and Greenland is spreading over the oceans, slowing down Earth’s rotation — much like a skater spinning with their arms over their head, but spinning slower if the arms are tucked along the body.

“If that ice had not melted, if we had not had global warming, then we would already be having a leap negative leap second, or we would be very close to having it,” Agnew said. Meltwater from Greenland and Antarctica ice sheets has is responsible for a third of the global sea level rise since 1993, according to NASA.

The mass shift of this melting ice is not only causing changes in Earth’s rotation speed, but also in its rotation axis, according to research led by Benedikt Soja, an assistant professor at the department of civil, environmental and geomatic engineering of The Swiss Federal Institute of Technology in Zurich, Switzerland. If warming continues, its effect might become dominant. “By the end of this century, in a pessimistic scenario (in which humans continue to emit more greenhouse gases) the effect of climate change could surpass the effect of the moon, which has been really driving Earth’s rotation for the past few billions of years,” Soja said.

At the moment, potentially having more time to prepare for action is helpful, given the uncertainty of long-term predictions on Earth’s spinning behavior. “I think the (faster spinning) is still within reasonable boundaries, so it could be natural variability,” Soja said. “Maybe in a few years, we could see again a different situation, and long term, we could see the planet slowing down again. That would be my intuition, but you never know.”

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July 21 (UPI) — SpaceX scrubbed the launch of two O3b mPOWER satellites for Luxembourg-based SES on Monday from Cape Canaveral Space Station.

The Falcon 9 was scheduled to lift off at 5:27 p.m. from Pad 40 but, with 11 seconds on the countdown clock, it was aborted.

During the SpaceX webcast, a launch director said: “T-minus 15 seconds” and was followed by “hold, hold, hold.”

A reason for the scrub wasn’t given. The favorable weather outlook was listed as 50% for a “go for launch,” Florida Today reported.

The next launch opportunity is a two-hour window starting at 5:12 p.m. Tuesday with 25% odds of favorable weather, according to the 45th Weather Squadron.

SpaceX earlier launched eight satellites for the company into medium Earth orbit. They are stationed about 5,000 miles above Earth.

Deployment is roughly two hours after the launch.

The two mPOWER satellites were delivered by Boeing to Florida earlier this month.

“This next-generation satellite network was designed to bring connectivity to the ‘other three billion’ — those who lack consistent, reliable access to communications systems,” SES said on its website. “For the first time, telcos connect entire island nations, remote industries access digital tools and governments conduct vital operations to the harshest terrains.”

The same first-stage booster launched the last two satellites for SES in December 2024. The booster was also involved in the NASA Crew-10 launch and two Statlink missions.

About 8 1/2 minutes after liftoff, the booster is scheduled to land on “Just Read the Instructions” droneship stationed in the Atlantic Ocean.

There have been 128 landings on the vessel with 478 in Florida and California.

SpaceX is planning the launch of a Falcon 9 at 11:13 a.m. PDT Tuesday from Vandenberg Space Force Base in California. They are NASA’s Tandem Reconnection and Cusp Electrodynamics Satellites, or TRACER, and are intended to study the interaction of the Sun’s solar particles with the Earth’s magnetic field.

Dust devils are a common sight whirling across the Alvord Desert’s flat expanse. Dry for most of the year, this tract of southeastern Oregon interests scientists seeking to understand the flighty vortices, phenomena that also occur on Mars and potentially elsewhere in our solar system. The playa and its dust stem from the most recent ice age, when a massive pluvial lake covered the area. This lake left the basin covered in bright salt and mineral deposits—and surrounded by evidence of catastrophic flooding.

The images above, acquired with the OLI (Operational Land Imager) on Landsat 8 on June 29, 2025, show the Alvord Desert in false color (left) and natural color (right). The summit of Steens Mountain stands more than a vertical mile above the desert floor to the west, and a steep escarpment borders the playa on the east.

The false-color image (OLI bands 6-5-4) indicates that some water was present in the desert at the time. The basin holds seasonal runoff from Steens Mountain and may also partially fill with rainfall. The last time it was flooded year-round was 1982 through 1985 due to unusually high mountain snowpack, according to the Bureau of Land Management. Alvord Lake, another shallow seasonal lake, is visible farther south.

In recent years, researchers have sought to better understand dust devils by measuring meteorological conditions in the Alvord Desert. The convective vortices are powered by the Sun’s heating of the land surface, but the details of their drivers and inner workings are still somewhat mysterious.

Dust devils are limited to arid areas on Earth but widespread—and sometimes much larger—on Mars. Dust lofted into the Martian atmosphere tends to stay there for a long time and likely plays a significant role in the Martian climate. And while dense atmospheric dust might reduce the available sunlight for powering equipment used to study the planet, forceful dust devil winds can actually play a beneficial role by clearing off solar panels, scientists note.

The Alvord Desert has not always shared these similarities with Mars. During the late Pleistocene epoch, from about 40,000 to 12,000 years ago, Alvord Lake was one of many sprawling lakes filling in basins of the Basin and Range province. Scientists believe the ice-age version of Alvord Lake was over
80 miles (130 kilometers) long and up to 280 feet (85 meters) deep at its highest level.

What’s more, geologists have discovered evidence of at least one catastrophic outburst flood that shaped the landscape for tens of miles downstream. Around 13,000 years ago, the lake breached Big Sand Gap, releasing multiple cubic miles of water into the Coyote Lake basin and ultimately into the Owyhee and Snake Rivers east and north of this scene. Floodwaters carved canyons, scoured bedrock, and deposited boulders up to 100 feet (30 meters) above present-day river channels. Large-scale “fill-and-spill” events such as these shaped the landscape across western North America during this period (for example, in Washington’s Channeled Scablands) due to the presence of many large ice- or debris-dammed lakes.

NASA Earth Observatory images by Michala Garrison, using Landsat data from the U.S. Geological Survey. Photo by Bonnie Moreland. Story by Lindsey Doermann.