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When NASA’s DART mission crashed into the asteroid Dimorphos, the first stage of the impact saw the spacecraft’s solar panels strike and pulverize two large boulders on the target, debris from which spun off in two directions. That ejection created enough momentum to give Dimorphos an extra kick on top of the direct effects of the kinetic impact, according to a new analysis of the collision.

DART, the Double Asteroid Redirection Test, slammed into the 558-foot-wide (170-meter-wide) asteroid Dimorphos on Sept. 26, 2022. The force of the impact shortened Dimorphos’ orbit around its larger asteroid companion, Didymos, by about 32 minutes. The point of the mission was to show that we could deflect hazardous asteroids if they’re ever found to be on a collision course with Earth.

Volcanic eruptions at Earth’s surface have significant consequences. Smaller ones can scare tourists on Mount Etna or disrupt air traffic.

Giant, large-scale eruptions can have more serious impacts. One such event contributed to the demise of the dinosaurs 66 million years ago. Giant volcanoes also triggered events that led to the largest mass dying on Earth, the Permian–Triassic extinction 252 million years ago).

But what fuels a giant eruption, and how does it make its way to the surface from deep within the planet?

In a new study published in Communications Earth and Environment, we show that columns of hot rock, which rise some 3,000 kilometres through Earth’s mantle and cause giant eruptions, are connected to continent-sized source regions we call BLOBS.

Hidden blobs within Earth

BLOBS are hot regions at the bottom of Earth’s mantle (between about 2,000km and 3,000km in depth) which might be composed of different material compared with the surrounding mantle rocks.

Scientists have long known about these two hot regions under the Pacific Ocean and Africa. Geologist David Evans from Yale University suggested the acronym BLOBS, which stands for Big LOwer-mantle Basal Structures.

These BLOBS have possibly existed for hundreds of millions of years. It is unclear whether they’re stationary or if they move around as part of mantle motion (called convection).

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Read more:
Volcanoes, diamonds, and blobs: a billion-year history of Earth’s interior shows it’s more mobile than we thought

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Mantle plumes were the implicit link in previous studies relating BLOBS to giant volcanic eruptions. Their shape is a bit like a lollipop: the “stick” is the plume tail and the “candy” is the plume head.

Mantle plumes rise very slowly through the mantle because they transport hot solid rock, not melt or lava. At lower pressures in the uppermost 200km of Earth’s mantle, the solid rock melts, leading to eruptions.

A long-sought relationship

In our new study, we simulated mantle convection from 1 billion years ago and found that mantle plumes rise from moving BLOBS and can sometimes be gently tilted.

Giant volcanic eruptions can be identified by the volume of volcanic rocks preserved at Earth’s surface. The ocean floor preserves detailed fingerprints of mantle plumes for the past 120 million years or so (there is not much seafloor older than that).

Oceanic plateaus, such as the Ontong Java-Manihiki-Hikurangi plateau currently in the southwest Pacific Ocean, are linked to plume heads. In contrast, series of volcanoes such as the Hawaii-Emperor seamount chain and the Lord Howe seamount chain are linked to plume tails.

We used statistics to show that the locations of past giant volcanic eruptions are significantly related to the mantle plumes predicted by our models. This is encouraging, as it suggests that the simulations predict mantle plumes in places and at times generally consistent with the geologic record.

Are BLOBS fixed or mobile?

We showed that the considered eruption locations fall either onto or close to the moving BLOBS predicted by our models. Eruption locations slightly outside moving BLOBS could be explained by plume tilting.

We represented fixed BLOBS with 3D images of Earth’s interior, created using seismic waves from distant earthquakes (a technique called seismic tomography). One out of the four seismic tomographic models that we considered matched the locations of past giant volcanic eruptions, implying that the fixed BLOBS scenario cannot be ruled out for geologically recent times – the past 300 million years.

One of the next steps for this research is to explore the chemical nature of BLOBS and plume conduits. We can do so with simulations that track the evolution of their composition.

Our results suggest the deep Earth is dynamic. BLOBS, which are some 2,000km below Earth’s surface, move hundreds of kilometres over time, and are connected to Earth’s surface by mantle plumes that create giant eruptions.

To take a step back and keep things in perspective: while deep Earth motions are significant over tens of millions of years, they are generally in the order of 1 centimetre per year. This means BLOBS shift at roughly the rate at which human hair grows.

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Read more:
Where should we look for new metals that are critical for green energy technology? Volcanoes may point the way

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Aren’t the summer days supposed to be longer and the winter days shorter?

Since when have things gone in reverse for the summertime?

Since now, maybe? Starting today?

Okay, here’s what’s going on.

Planet Earth is set to spin a bit faster on three separate days this summer, officially starting today. The result will be shorter days, but don’t panic because the change will be so small that you won’t even notice.

The change is equal to several milliseconds that will be shaved off of the 24 hours it takes for Earth to complete a full rotation.

Now to your next question: How long are several milliseconds? It’s less than the time you’d take to blink your eye.

So why is this happening?

It takes the planet 24 hours, or one day, to complete a full rotation on its axis, which equals to 86,400 seconds. But Earth’s rotation could change by a millisecond — which is .001 seconds — or two every day.

Also, the orbit of the moon can have an effect on how fast the Earth spins.

“Our planet spins quicker when the moon’s position is far to the north or south of Earth’s equator,” according to TimeandDate.com.

“Earthquakes, volcanoes, tidal forces, subterranean geology, and many other mechanisms can cause the planet’s rotation to slow down or speed up, and those micro-adjustments can trend over time,” Popular Mechanics reported.

If you can recall, the 8.9 magnitude earthquake that hit Japan back in 2011 accelerated Earth’s rotation, shortening the length of the standard 24-hour day by 1.8 microseconds (0.0018).

These small, day-to-day fluctuations in the Earth’s rotational speed started to be measured in the 1950s with atomic clocks, where any number above or below the standard 86,400 seconds is called the length of day (LOD).

If you’re wondering what the shortest day ever was, that happened on July 5, 2024, when Earth completed its full rotation 1.66 milliseconds faster than the standard 86,400 seconds.

As for when this three-day event will happen, there are three days this summer when the moon will be around its furthest distance from Earth’s equator, resulting in the slight increase in Earth’s rotational speed.

Scientists are predicting that this will happen on July 9, July 22 and Aug. 5.

Today, July 9, will be shortened by 1.30 milliseconds. On July 22, Earth loses 1.38 milliseconds of the day. And Aug. 5, the day will be shortened by 1.51 milliseconds.

Astronomers have recently added a new member to the small club of confirmed interstellar objects. The icy wanderer, known as 3I/Atlas, was officially recognized this week by the International Astronomical Union’s Minor Planet Center (MPC).

Observations showed it is racing through the solar system on a hyperbolic path – one that will carry it back into interstellar space after a brief celestial cameo.

A fuzzy comet with incredible speed

Early images of 3I/Atlas revealed the hazy glow typical of a comet. “It looks kind of fuzzy,” said Peter Veres, an astronomer at the MPC who helped confirm the object’s status. “It seems that there is some gas around it, and I think one or two telescopes reported a very short tail.”

That fuzzy halo is created as sunlight warms the comet’s surface, releasing dust and gas that trail behind it. Current estimates suggest the nucleus spans six to 12 miles (10 to 20 kilometers).

Because icy bodies reflect sunlight efficiently, the true size may prove smaller if the surface is especially bright.

What is certain is the object’s speed. Preliminary calculations put its velocity at more than 60 km per second (roughly 135,000 mph). At that speed, solar gravity cannot capture it, confirming its extrasolar origin.

Spotting an interstellar traveler

The discovery began on Tuesday when a telescope in Chile, operated as part of the NASA-funded ATLAS survey, recorded an unfamiliar, rapidly moving speck.

Within hours, professional and amateur observers worldwide had combed archival data, tracing its motion back to at least June 14.

The collected positions fit a hyperbolic orbit – unmistakable evidence the object is diving in from beyond the Sun’s gravitational reach.

Richard Moissl, head of planetary defense at the European Space Agency, emphasized that 3I/Atlas poses no danger.

“It will fly deep through the solar system, passing just inside the orbit of Mars,” he said, adding that the flyby comes nowhere near a collision with Earth or the Red Planet.

Calculations show the interstellar comet will reach perihelion, its closest point to the Sun, on 29 October, then fade as it speeds back into the darkness over the next few years.

How interstellar comets differ

Unlike comets bound to the Sun, interstellar objects are born around distant stars. Jonathan McDowell of the Harvard–Smithsonian Center for Astrophysics explained the likely origin scenario.

“We think that probably these little ice balls get formed associated with star systems. And then as another star passes by, tugs on the ice ball, frees it out. It goes rogue, wanders through the galaxy, and now this one is just passing us,” he said.

In 2017, astronomers found the first known example, 1I/ʻOumuamua, whose odd shape and tumbling motion sparked contentious debate – including speculation it might be alien technology.

Two years later came 2I/Borisov, a more conventional comet with clear gas jets. 3I/Atlas now becomes the largest and fastest of the trio, offering scientists a fresh specimen to study.

Observations of a fast-moving comet

The MPC initially labeled the body A11pl3Z, but the “3I” prefix signifies its confirmed interstellar status. As data pours in, researchers aim to refine its orbit, rotation rate, and composition.

Scientists are particularly eager to learn whether its chemistry differs from solar system comets, which would provide clues about its natal environment.

Despite enthusiasm, a spacecraft intercept is beyond reach, since there is not enough time to plan, launch, and meet with an object moving this quickly and appearing on such short notice.

Ground-based and space-based telescopes will therefore carry the observational load, capturing spectra and high-resolution imagery while the interstellar comet remains within range.

Interstellar objects may be common

Mark Norris, an astronomer at the University of Central Lancashire, pointed out an intriguing statistic: modeling work suggests up to 10,000 interstellar objects could be drifting inside the solar system at any given moment – most of them too small or faint to detect.

The newly built Vera C. Rubin Observatory in Chile, scheduled to begin its wide-field survey soon, is expected to uncover many more. Such a flood of discoveries would transform the study of planetary system formation.

Each passerby carries a chemical and physical record of processes that occurred around alien suns. They deliver natural “samples” at no cost other than the telescopic time required to study them.

Fly-by science in action

Scientists will watch 3I/Atlas brighten through the northern autumn, hoping for unobstructed views of its coma chemistry.

Spectrographs on large telescopes may reveal ratios of carbon monoxide, carbon dioxide, and water vapor – benchmarks that help distinguish comets formed under different conditions.

Photometric monitoring can nail down its spin. Careful astrometry will improve the orbit and may even hint at non-gravitational forces from asymmetric outgassing.

Improving planetary defense capabilities

Beyond pure science, each interstellar detection enhances planetary defense capabilities.

Rapidly identifying an object’s orbit and assessing any hazard is a rehearsal for future surprises – though, happily, none of the known interstellar visitors have posed a threat.

For now, astronomers relish the serendipity. A cosmic snowball born around an unknown star has swung through humanity’s celestial neighborhood, offering a fleeting chance to study matter forged in a far-off corner of the galaxy.

With upgraded surveys on the horizon, the odds of such encounters – and the insights they carry – are only set to increase.

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