This masterpiece of ancient Celtic weaponry was discovered by a laborer who was working on a bridge over the River Thames in 1857. Named the Battersea Shield after the London neighborhood near where it was found, the bronze artifact shows no signs of use, leaving archaeologists wondering how it ended up at the bottom of the river.

According to the British Museum, which acquired the shield directly from the construction worker who found it nearly 170 years ago, the weapon is made of several pieces of sheet bronze fastened together with rivets. The shield is about 30.6 inches (77.7 centimeters) long and 14 inches (35.7 cm) wide, and it weighs roughly 7.5 pounds (3.4 kilograms). Originally, the thin bronze shield facing would have been affixed to a wooden or leather base to create a substantial shield, but no trace of the underlying material has survived.

Experts think the Battersea Shield dates to the Iron Age because of the Celtic-style decorations that have been hammered into the shield from the back. The circular shield boss in the middle — which served to protect the wearer's fist — is a specifically British form of decoration, according to the British Museum, suggesting the object was made in Britain and not imported from another Celtic culture.

Palmettes and interlocking S-shaped motifs adorn the shield, and there are 27 circular decorations filled with red glass enamel and bronze in the shape of swastikas, which were symbols of good luck in ancient Celtic culture. These ornaments could also represent eyes staring back at an enemy, archaeologist Sophia Adams, a curator at the British Museum, has suggested.

The shield likely predates the invasion of Rome; Julius Caesar and his forces invaded Britain in 55 and 54 B.C., but they left soon after. The Romans didn't return until the Roman emperor Claudius launched another invasion in A.D. 43, long after the shield was created sometime between 350 and 50 B.C.

Because there's no evidence of damage to the shield, it was probably never used in battle, according to Adams. Rather, the shield could have been thrown into the Thames as a ritual sacrifice to the river or to an important ancestor.

"There's something of a watery element to these shapes, the swirls and eddies," Adams said in a London Museum video. "So I wonder if there's almost an intention that this was meant to end up in the water."

The Battersea Shield is the "most famous object ever to be found in the Thames," archaeologist Kate Sumnall, a curator at the London Museum, said in the video. As such, it has become a potent symbol of ancient Britain and has been featured on items as diverse as postage stamps, cigarette boxes and CD cases.

Benin Bronze

Guldhøj Chair

Kerch Crown

Can you put together last week's Astonishing Artifact?

'> Battersea Shield: A 2,000-year-old Celtic shield that may have been 'sacrificed' in a ritual in the River Thames

Around 13,000 light-years from Earth lies an unusual binary star system, known as BP Crucis. It contains a blue hypergiant star roughly 60 times larger than the sun, dubbed Wray 977, alongside a neutron star — the undead and ultradense remains of a star that exploded via a supernova — that astronomers have labeled GX 301-2.

This stellar "zombie," which contains the same mass as our home star packed into an object roughly 12 miles (20 kilometers) across, is a type of neutron star called a pulsar, which has an extremely powerful magnetic field and spins rapidly. This means it constantly shoots out a wobbling beam of powerful electromagnetic radiation, including X-rays, into the cosmos at regular intervals. When this beam aligns with Earth — approximately every 11 minutes, in the case of GX 301-2 — our planet's telescopes detect a flash.

However, unlike most other known pulsars, GX 301-2 also emits frequent X-ray flares (separate from the regular beams), which cause it to shine much brighter at repeated intervals. And, until now, researchers were unsure why.

In the new study, published Sept. 18 in the journal Science Advances, researchers used the X-ray Imaging and Spectroscopy Mission (XRISM) — a space telescope jointly operated by NASA and the Japan Aerospace Exploration Agency — to take a closer look at BP Crucis. In doing so, they discovered that the neutron star flared up every time it passed through a giant plume of "stellar wind plasma" shooting out of its hypergiant partner.

This is the first time that researchers have ever detected this type of stellar material interacting with a neutron star, or with any other similar stellar remnant, opening the door to studying similar systems in the future.

"We've never before seen clear indications of wind plasma falling onto a compact object," study first author Roi Rahin, a researcher at the University of Maryland, Baltimore County (UMBC) and NASA's Goddard Space Flight Center, said in a statement. "We can now test our understanding of these processes in much greater detail."

Whoever smelt it … explodes?

All stars that actively burn via nuclear fusion release streams of radiation and charged particles known as stellar wind. The sun emits such a stream, known as the solar wind, which can trigger vibrant aurora displays near Earth's poles.

However, massive stars like Wray 977 blow stellar winds that are much more extreme. The blue hypergiant emits a single giant plume of concentrated ionized gas, or plasma, that spills out at around 335,000 mph (540,000 km/h). (Scientists think the stellar wind is likely sculpted into a single, concentrated plume due to the gravitational effects of the star's ultradense neighbor.)

GX 301-2 circles Wray 977 every 41.5 days and experiences its X-ray flares when it reaches its closest and farthest points from its partner, with the strongest flares occurring at its closest point. As a result, researchers had long suspected that the flares occurred when the neutron star passed through the stellar wind plume. However, they had no way of proving this without more evidence.

During a 16-hour observation period coinciding with one of the neutron star's flares, researchers used XRISM to capture highly detailed X-ray spectra, revealing "rapidly changing emission and absorption lines" that showed how the plume ebbed and flowed around GX 301-2, NASA representatives wrote.

"We could see how the dense stream of plasma acts very close to the neutron star," study co-author Nazma Islam, an astronomer at the Manipal Centre for Natural Sciences in India and formerly a researcher at UMBC and NASA Goddard, said in the statement. "It was clear that these observations were groundbreaking, but at the same time this meant the analysis had to be especially detailed."

Using this data, the researchers could simulate exactly how the plasma fell onto and swirled around the passing neutron star. When enough stellar material has accumulated on its surface, the stellar zombie explodes, unleashing the bright flashes we can detect on Earth.

The team now hopes to use XRISM to study future flaring events to better understand the relationship between GX 301-2 and Wray 977's windy plume.

"The BP Crucis system is an ideal laboratory for studying wind-fed pulsar accretion," Brian Williams, XRISM project scientist at NASA Goddard, said in the statement, and XRISM is "an ideal instrument for advancing our understanding of the processes involved."

'> A giant cosmic 'fart' is making a wobbling zombie star repeatedly flash us, 'groundbreaking' observations reveal

And lurking all around this colorful nursery are strange objects that challenge the very definition of a star.

Stars come in all shapes and sizes, from massive stars that explode as supernovas after only a few million years to the smallest and most common stars, red dwarfs, which last for many billions of years. However, there is also a class of substellar objects called brown dwarfs — objects halfway between giant gas planets, like Jupiter, and stars.

In the hunt for tiny brown dwarfs in IC 348, researchers used Webb’s NIRCam instrument in 2024 to survey part of IC 348 and found 39 brown dwarf candidates. The following year, Webb’s NIRSpec instrument studied the light of 15 of them. Nine were identified as new substellar members of the cluster, with the faintest estimated to have masses of around two Jupiters — the least massive brown dwarfs ever found.

How small the smallest brown dwarf can be is an open question in astrophysics. They form as molecular clouds of dust and gas collapse under their own gravity, much like regular stars do. However, unlike stars, brown dwarf cores never become hot enough to fuse hydrogen into helium. The brown dwarfs — or "failed stars," as they're sometimes called — in this JWST image will help researchers constrain the limits of how tiny these strange objects can get.

The upper-right portion of the panorama provides a dramatic look at another stage of star formation. Protostars hidden within the dusty environment fire jets into nearby gas and dust, producing luminous, eye-catching jets and streams known as Herbig-Haro objects. These gargantuan jets can stretch trillions of miles into space; just one tiny detail in one of JWST's biggest images yet.

But if that tremendous view still isn't enough for you, IC 348 was also recently snapped by NASA's Chandra Observatory, which captured the stellar nursery and other cosmic objects shining purple in brilliant X-ray light.

'> James Webb telescope shares one of its biggest images ever, with record-breaking stars hiding in the dust the sun while still escaping?

Many objects have reached much closer than Mercury, including asteroids, comets and spacecraft, experts told Live Science.

At its closest point to the sun, called perihelion, Mercury comes within 29 million miles (47 million kilometers) of our star, according to NASA.

But several known asteroids come even closer. Scott Sheppard, an astronomer at Carnegie Science, an independent research institute in Washington, D.C., said such asteroids, with orbits that cross Mercury's, are called Mercury-crossers. They have highly eccentric orbits, meaning "they did not form in this location but were likely scattered from the main asteroid belt towards the Sun," he told Live Science in an email. A search through NASA's Small-Body Database for such asteroids shows 2024 YL3 is the current record holder. This 463-foot-long (141 meters), skyscraper-size rock has a perihelion of 6.4 million miles (10.3 million km).

Another group of celestial objects, though, may beat 2024 YL3. These are proposed asteroids that are thought to have circular orbits within Mercury's path. Dubbed Vulcanoids, their name comes from Vulcan, a theoretical planet once hypothesized to exist in this region.

Martin Beech, a professor emeritus of physics at the University of Regina in Canada, told Live Science in an email that numerical models show such asteroids would have stable orbits between 5.58 million and 23.23 million miles (8.98 million to 37.39 million km) from the sun's center. This means some Vulcanoids may whiz even nearer the sun than Mercury-crossers do. There's just one glitch: Like their namesake planet, Vulcanoids haven't been shown to exist, and a 2013 study found no trace of them.

But some spacecraft have come much, much closer. For instance, NASA's Parker Solar Probe, which launched in 2018, studied the sun's outer atmosphere, or corona. For the primary mission's final three orbits, the probe took an eccentric path with a perihelion of merely 4.5 million miles (7.3 million km) from the sun's center. At this distance, illustrated graphically on the mission's official webpage, the spacecraft flew through the corona, where a carbon foam shield protected the probe from the extreme heat.

"Sungrazers" and "sun-diving" comets

Another class of natural objects — dubbed sungrazing comets — reach closer still. A 2018 study described such comets as coming closer than 1.49 million miles (2.39 million km) of the sun's center, although any of these comets' precise solar proximity would depend on their orbital parameters.

Man-To Hui, a researcher at the Shanghai Astronomical Observatory, told Live Science that small sungrazers — some of which are just 30 feet (10 m) wide —break up as they rotate because they get nonuniformly heated, while the sun's powerful gravity pulls apart larger ones. Nonetheless, several escape unscathed; one of the closest observed so far was the Great Southern Comet of 1887, which came within an incredible 446,187 miles (718,070 km) from the sun.

But the real "winners" are "sundiving," or "sunstriking," comets. Such comets likely abounded in the early solar system, although they're thought to be rare nowadays. These comets would cross the sun's visible surface, or photosphere, plunging into the sun. Although no one has detected such a sundiver yet, the 2018 study noted that a comet would need a perihelion less than the sun's radius, or 432,244 miles (695,630 km) from the sun's center. There are no second passes, though ‪—‬ all sundiving comets are destroyed within the sun.

So, the detected object that got closest to the sun was the Great Southern Comet of 1887. If a sundiver is ever spotted, however, it would become the new record-holder, edging out the Great Southern Comet by 13,943 miles (22,439 km).

See how much you know about the sun with our sun quiz!

'> What is the closest any object has gotten to the sun?