JWST observation of Interstellar comet 3I/ATLAS.

Fortune must have had a pretty good time when the solar nebula exploded, tossed, roared, and turned around 4.6 billion years ago. If the slightest something hadn’t gone the way it did, we wouldn’t be here writing and studying the ‘what ifs’ and ‘what is’ of our universe. One night, like our good old Galileo, you must go starwatching. Peer up at the sky in the dark of the night before sunrise, and there you’ll see planet Jupiter, as one of the brightest stars in our sky. For all its brightness, bright Jupiter holds within itself an ancient blessing, one that is responsible for the stability of our solar system. The most powerful Jovian, a consequence of its corporeal form, Jupiter has the highest gravitational pull among all the planets in our solar system. 

Bigger than pure imagination.

Gravity is a fundamental force of space-time. Generally we have learned that the heavier an object, the stronger its gravitational pull. Newton’s law of gravitation describes this force as attractive in nature as well as directly proportional to the product of the masses involved.

Now imagine, really imagine with utmost precision, how humongous a planet Jupiter is. Compared to our home (also known as Planet Earth, the fifth largest in the solar system), Jupiter is actually a titan with immense mass. The name, taken after the Roman king of Gods, befits the planet. No amount of pictures can materialise how big it is for us, so imagination is an onerous task. NASA says if it were hollow, Jupiter could fit 1000 Earths inside it. Its radius is about 10 to 11 times that of our planet.

With all the enormous matter, Jupiter’s gravity can change even the orbits of asteroids. Not to mention, the planet has intense magnetic fields and so many moons (as of now, 95 moons are officially recognised), rings, and Trojan asteroids in its system! 

Resembling the Sun

Since the inception of the planet, there has never been a quiet moment. 4.6 billion years ago, Jupiter was formed by gravity pulling gas into a raging orb. Truth be told, we don’t exactly know how. Made of hydrogen-helium gas in hydrostatic equilibrium, the planet has a dynamic atmosphere and resembles the Sun. Maybe, if ever nuclear fusion (what powers the Sun) was possible on Jupiter (it is not possible on Jupiter as it doesn’t meet the temperature and pressure criteria due to not enough mass), it could’ve been another Sun.

Hydrostatic equilibrium

Hydrostatic equilibrium means the balance between upward-directed pressure force and the downward-directed force of gravity. Jupiter’s hydrostatic equilibrium prevents it from collapsing under its own weight.

Enigmatic Jove, with its signature belts and zones, cyclones and anticylones, and mesmerising auroras, tells us so little. Shrouded in mystery, scientists continue to probe for better understanding this tale.

Interaction, Aid, and this Life.

If you could travel to Jupiter, you would be crushed. Crushed either by the heavy gravity or crushed by the powerful storms. Amidst all the sizzling rage and extreme phenomena, the solar system is dependent on Jupiter’s gravity. The gravitational interactions that the planets in our solar system have with one another has great effects. Newton’s law also explains that the strength of the gravitational force is inversely proportional to the square of the distance between the masses. For Jupiter, this ultimately means that it sort of becomes the guardian whose presence shaped many environments. Jupiter’s gravity influences and keeps the orbits in place. In fact, both Jupiter’s and the Sun’s gravity influences a point called the barycenter, which is the centre of mass of two or more bodies that orbit each other. Only the Jupiter-Sun barycenter lies outside the Sun’s surface. Therefore, the barycenter of our entire solar system (which is relative to the Sun) is affected and aided by Jupiter.

Studies also show that Jupiter’s gravitational influence brought many life-enabling elements to Earth during its early days. Along the way, it has also flung space materials inward as well as deflect materials outward. Long story short, here we are, living this life. Just some gravity keeping things in check.

Published – October 17, 2025 03:48 pm IST

Over 10 lakh interstellar objects the size of the Statue of Liberty are drifting unseen in the fringes of our solar system, a new yet-to-be peer-reviewed study has stated. Though unlikely to come in close contact with Earth, these cosmic nomads have travelled from our nearest stellar neighbours and may have been captured from other star systems through gravitational interactions.

The study, uploaded on arXiv, involved researchers running simulations about how much interstellar material was ejected our way from Alpha Centauri, our closest stellar star system. The simulations showed that over 10 lakh macroscopic objects, each wider than 100 metres were moving surreptitiously outside our cosmic backyard.

Notably, the entire Alpha Centauri star system is moving towards us at a rapid pace and will reach the closest point to the Sun in approximately 28,000 years. Scientists say the number of alien objects entering our solar system will also increase exponentially then. 

One of the notable examples of an interstellar visitor paying us a visit was ‘Oumuamua’. Discovered in 2017, it was the first known object to enter our solar system from interstellar space. Its discovery prompted scientists to look for more such objects, leading to the identification of Comet Borisov in 2019, another interstellar visitor.

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Asteroid 2024 YR4

While unidentified interstellar objects roam around, scientists are keeping a close eye on asteroid 2024 YR4 whose chances of colliding with Earth have increased substantially in recent weeks. The asteroid was first spotted in late December by scientists at the NASA-funded Asteroid Terrestrial-impact Last Alert System station in Chile.

At the time, the space rock was given a 1.3 per cent chance of collision with Earth which was nearly doubled to 2.3 per cent, within the space of a week. The asteroid, measuring around 130 to 300 feet across, may not be big enough to cause a civilization collapse upon the impact but it is big enough to inflict major damage to a big city.

Scientists say that there have been several objects in the past that have risen on the risk list and eventually dropped off as more data have come in. New observations may result in the reassignment of this asteroid to zero as more data is analysed.

Scientists have claimed that an interstellar visitor, much larger than any celestial body in our solar system, might have dramatically altered the orbits of the planets. The research, yet to be peer-reviewed but published in the arXiv preprint database, posits that this cosmic intruder, possibly eight times the mass of Jupiter, passed very close to where Mars orbits today, potentially affecting the orbits of Jupiter, Saturn, Uranus, and Neptune.

For a long time, scientists have stated that in ideal conditions, the planets should have lied in circles that are arranged concentrically around the Sun and in the same plane — meaning if you viewed them edge-on, you would only see a line. However, since planets orbit the Sun in different orbits in three-dimensional space, it makes it almost impossible for them to come together in a straight line.

To understand the discrepancy, the researchers considered a scenario around four billion years ago when a star-sized alien object, whizzed around in our solar system. They ran extensive simulations through 50,000 scenarios, each spanning 20 million years while adjusting various parameters like the visitor’s mass, speed, and closest approach to the sun.

These simulations indicated that in about one per cent of the cases, this cosmic guest could have reshaped the orbits of these planets to match what we observe today.

“We estimate that there is about a 1-in-100 chance that such a flyby produces a dynamical architecture similar to that of the solar system,” the study highlighted.

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Study results

The findings showed that the interstellar object might have come within 1.69 astronomical units (AU) of the Sun, which is just beyond Mars’ current orbit. An astronomical unit is roughly the distance from Earth to the Sun. This proximity would have been close enough for the visitor’s gravity to tug on our planets, nudging them into new paths.

“The scenario of a close encounter with a substellar object offers a plausible explanation for the origin of the moderate eccentricities and inclinations and the secular architecture of the planets.”

Previous theories suggested that the orbits may have been reshaped due to planetary interactions within the solar system. However, the new study challenges this belief and argues that a one-off event could explain these irregularities.

The scientists added that further exploration of this scenario was needed which might detail the “effect of substellar flybys on the dynamical excitation of minor planets in the asteroid belt and the trans-Neptunian belts”.

A team of astronomers has uncovered an Earth-like planet orbiting a star located 4,000 light years away from the solar system, potentially offering insights into Earth’s distant future. The rocky planet, about the same mass as Earth, revolves around a white dwarf in the constellation Sagittarius.

The discovery brings a glimmer of hope for Earth’s survival when our sun enters its final stages. It suggests that Earth could potentially avoid being consumed by the expanding sun, opening up possibilities for human migration to the outer solar system, with moons such as Europa, Callisto, and Ganymede around Jupiter, or Enceladus near Saturn, becoming possible havens for future generations.

What is a white dwarf?

A white dwarf is a star’s remnant after it has run out of nuclear fuel and shed its outer layers. It symbolises the sun’s eventual fate. The sun will grow into a red giant as its nuclear fuel runs out, then shrink to become a white dwarf. The extent of its expansion will determine which planets in the solar system will be engulfed – Mercury and Venus are likely to be consumed. But what about Earth?

In a study published in Nature Astronomy, researchers from the University of California, Berkeley, used the Keck Telescope in Hawaii to observe a system designated KMT-2020-BLG-0414. The system contains a white dwarf star with an Earth-sized planet in an orbit twice as far from the star as Earth is from the sun. Alongside the planet is a brown dwarf – a planet roughly 17 times the mass of Jupiter.

This finding supports the theory that as the sun expands into a red giant, its loss of mass will push the planets into more distant orbits. This phenomenon could allow Earth to escape destruction. Jessica Lu, an associate professor of astronomy at UC Berkeley, noted, “Whether life can survive on Earth through that (red giant) period is unknown. But certainly, the most important thing is that Earth isn’t swallowed by the Sun when it becomes a red giant.”

Future of Earth

“We do not currently have a consensus whether Earth could avoid being engulfed by the red giant sun in six billion years,” said Keming Zhang, the lead author and a former doctoral student at the UC Berkeley, who is now an Eric and Wendy Schmidt AI in Science Postdoctoral fellow at UC San Diego.

“In any case, planet Earth will only be habitable for another billion years, at which point Earth’s oceans would be vaporized by the runaway greenhouse effect-long before the risk of getting swallowed by the red giant.”  

Could humanity find refuge beyond Earth? As the sun swells into a red giant, the habitable zone in the solar system will shift outward to the orbits of Jupiter and Saturn. Many of their moons, such as Europa and Callisto, could become ocean worlds capable of supporting life. Zhang suggested, “Humanity could migrate out there.”

The crescent Earth rises above the lunar horizon in this undated NASA handout photograph taken from the Apollo 17 spacecraft in lunar orbit during the final lunar landing mission in the Apollo program in 1972.
| Photo Credit: Reuters

During the Apollo 17 mission in 1972 – the last time people walked on the moon – U.S. astronauts Harrison Schmitt and Eugene Cernan collected about 243 pounds (110.4 kg) of soil and rock samples that were returned to Earth for further study.

A half century later, crystals of the mineral zircon inside a coarse-grained igneous rock fragment collected by Schmitt are giving scientists a deeper understanding about the moon’s formation and the precise age of Earth’s celestial partner.

The moon is about 40 million years older than previously thought – forming more than 4.46 billion years ago, within 110 million years after the solar system’s birth, scientists said on Monday, based on analyses of the crystals.

Chandrayaan-3 | India lights up the dark side of the moon  

The leading hypothesis for lunar formation is that during the solar system’s chaotic early history a Mars-sized object called Theia slammed into primordial Earth. This blasted magma – molten rock – into space, forming a debris disk that orbited Earth and coalesced into the moon. But the exact timing of the moon’s formation has been hard to nail down.

Mineral crystals were able to form after the magma cooled and solidified. The researchers used a method called atom probe tomography to confirm the age of the oldest-known solids that formed after the giant impact, the zircon crystals inside the fragment of a type of rock called norite collected by Schmitt.

“I love the fact that this study was done on a sample that was collected and brought to Earth 51 years ago. At that time, atom probe tomography wasn’t developed yet and scientists wouldn’t have imagined the types of analyses we do today,” said cosmochemist Philipp Heck, senior director of research at the Field Museum in Chicago, a University of Chicago professor and senior author of the study published in the journal Geochemical Perspectives Letters.

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“Interestingly, all the oldest minerals found on Earth, Mars and the moon are zircon crystals. Zircon, not diamond, lasts forever,” UCLA planetary scientist and study co-author Bidong Zhang added.

The rock containing the zircon was collected in the Taurus-Littrow valley at the southeastern edge of the lunar Mare Serenitatis (Sea of Serenity) and stored at NASA’s Johnson Space Center in Houston.

“Zircons are very hard and tough and survive the breakdown of rocks during weathering,” Heck said.

A study led by Zhang published in 2021 used a technique called ion microprobe analysis to measure how many atoms of uranium and lead were in the crystals, calculating the age of the zircon based on the decay of radioactive uranium to lead over time. That age needed to be confirmed through another method because of a potential complication involving lead atoms if defects existed in the zircon crystal structure.

The new study used atom probe tomography to determine there were no complications involving the lead atoms, confirming the age of the crystals.

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“I see this as a great example of what the nanoscale, or even atomic scale, can tell us about big-picture questions,” said study lead author Jennika Greer, a cosmochemist at the University of Glasgow in Scotland.

The moon, which orbits Earth at an average distance of about 239,000 miles (385,000 km), has a diameter of about 2,160 miles (3,475 km), a bit more than a quarter of our planet’s diameter.

“The giant impact that formed the moon was a cataclysmic event for Earth and changed Earth’s rotational speed. After that, the moon had an effect on stabilizing Earth’s rotational axis and slowing down Earth’s rotational speed,” Heck said. “The formation date of the moon is important as only after that Earth became a habitable planet.”

“The moon helps stabilize Earth’s axis for a stable climate,” Zhang added. “The moon’s gravitational pulls help shape the ocean’s ecosystem. The moon is inspirational to human cultures and explorations. And NASA and other space agencies see the moon as a steppingstone for future deep-space explorations.”

In May 2020, some unusual rocks containing distinctive greenish crystals were found in the Erg Chech sand sea, a dune-filled region of the Sahara Desert in southern Algeria. On close inspection, the rocks turned out to be from outer space: lumps of rubble billions of years old, left over from the dawn of the Solar System. Image for Representation.
| Photo Credit: Getty Images/iStockphoto

In May 2020, some unusual rocks containing distinctive greenish crystals were found in the Erg Chech sand sea, a dune-filled region of the Sahara Desert in southern Algeria.

On close inspection, the rocks turned out to be from outer space: lumps of rubble billions of years old, left over from the dawn of the Solar System.

They were all pieces of a meteorite known as Erg Chech 002, which is the oldest volcanic rock ever found, having melted long ago in the fires of some now-vanished ancient protoplanet.

In new research published in Nature Communications, we analysed lead and uranium isotopes in Erg Chech 002 and calculated it is some 4.56556 billion years old, give or take 120,000 years. This is one of the most precise ages ever calculated for an object from space – and our results also cast doubt on some common assumptions about the early Solar System.

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The secret life of aluminium

Around 4.567 billion years ago, our Solar System formed from a vast cloud of gas and dust. Among the many elements in this cloud was aluminium, which came in two forms.

First is the stable form, aluminium-27. Second is aluminium-26, a radioactive isotope mainly produced by exploding stars, which decays over time into magnesium-26.

Aluminium-26 is very useful stuff for scientists who want to understand how the Solar System formed and developed. Because it decays over time, we can use it to date events – particularly within the first four or five million years of the Solar System’s life.

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The decay of aluminium-26 is also important for another reason: we think it was the main source of heat in the early Solar System. This decay influenced the melting of the small, primitive rocks that later clumped together to form the planets.

Uranium, lead and age

However, to use aluminium-26 to understand the past, we need to know whether it was spread around evenly or clumped together more densely in some places than in others.

To figure that out, we will need to calculate the absolute ages of some ancient space rocks more precisely.

Looking at aluminium-26 alone won’t let us do that, because it decays relatively quickly (after around 705,000 years, half of a sample of aluminium-26 will have decayed into magnesium-26). It’s useful for determining the relative ages of different objects, but not their absolute age in years.

But if we combine aluminium-26 data with data about uranium and lead, we can make some headway.

There are two important isotopes of uranium (uranium-235 and uranium-238), which decay into different isotopes of lead (lead-207 and lead-206, respectively).

The uranium isotopes have much longer half-lives (710 million years and 4.47 billion years, respectively), which means we can use them to directly figure out how long ago an event happened.

Meteorite groups

Erg Chech 002 is what is known as an “ungrouped achondrite”.

Achondrites are rocks formed from melted planetesimals, which is what we call solid lumps in the cloud of gas and debris that formed the Solar System. The sources of many achondrites found on Earth have been identified.

Most belong to the so-called Howardite-Eucrite-Diogenite clan, which are believed to have originated from Vesta 4, one of the largest asteroids in the Solar System. Another group of achondrites is called angrites, which all share an unidentified parent body.

Still other achondrites, including Erg Chech 002, are “ungrouped”: their parent bodies and family relationships are unknown.

A clumpy spread of aluminium

In our study of Erg Chech 002, we found it contains a high abundance of lead-206 and lead-207, as well as relatively large amounts of undecayed uranium-238 and uranium-235.

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Measuring the ratios of all the lead and uranium isotopes was what helped us to estimate the age of the rock with such unprecedented accuracy.

We also compared our calculated age with previously published aluminium-26 data for Erg Chech 002, as well as data for various other achondrites.

The comparison with a group of achondrites called volcanic angrites was particularly interesting. We found that the parent body of Erg Chech 002 must have formed from material containing three or four times as much aluminium-26 as the source of the angrites’ parent body.

This shows aluminium-26 was indeed distributed quite unevenly throughout the cloud of dust and gas which formed the solar system.

Our results contribute to a better understanding of the Solar System’s earliest developmental stages, and the geological history of burgeoning planets. Further studies of diverse achondrite groups will undoubtedly continue to refine our understanding and enhance our ability to reconstruct the early history of our Solar System.

Evgenii Krestianinov, PhD candidate, Research School of Earth Sciences, Australian National University

This article is republished from The Conversation under a Creative Commons license. Read the original article.