Have you ever stopped to wonder where Earth — and every planet in the universe — actually came from? Not in a philosophical sense, but in a real, physical, almost violent sense: spinning gas, colliding dust, gravity doing its slow and patient work over millions of years?

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This April 2026, NASA’s James Webb Space Telescope handed us something extraordinary: a pair of side-by-side images showing two planet-forming discs in breathtaking detail. They look like glowing rainbow spinning tops frozen in the dark. But behind that beauty lies a window into our own origin story.

Stay with us to the end. We promise it’s worth every second.

📋 Table of Contents

1. What Did Webb Just Show Us?
2. Why Does the Edge-On View Change Everything?
3. What Are We Actually Seeing in Those Colors?
4. How Do Planets Actually Form? Step by Step
5. What Is That Gap in Oph 163131 Telling Us?
6. How Does ALMA Fit Into the Picture?
7. Why Is Webb’s Growing Legacy So Important?
8. Conclusion: A Universe That’s Always Building

When Dust Becomes a World: Webb’s Latest Window on Planet Birth

What Did Webb Just Show Us?

On April 3, 2026, ESA released the James Webb Space Telescope’s Picture of the Month. And it wasn’t just one disc — it was two. Side by side. Each one a nursery for future planets.

The two discs are called Tau 042021 and Oph 163131. Their catalog names — 2MASS J04202144+2813491 and 2MASS J16313124-2426281 — are less poetic, but equally precise. Tau 042021 sits roughly 450 light-years away in the constellation Taurus. Oph 163131 is a little farther out, about 480 light-years away in Ophiuchus.

In cosmic terms, that’s practically next door. And yet, what we’re seeing there is completely alien to anything we experience in our quiet, well-settled solar system.

Quick fact: These images were captured under Webb observing programme #2562, led by principal investigators F. Ménard and K. Stapelfeldt. The programme’s goal is to understand how dust evolves inside edge-on protoplanetary discs.

These are young stars. They haven’t been around long at all. And the thick, swirling discs of gas and dust around them are the raw ingredients — the flour and water before the bread is even mixed — of entire planetary systems.

Why Does the Edge-On View Change Everything?

A Rare Geometry That Solves a Big Problem

Most planet-forming discs, as seen from Earth, are tilted at some angle. You see a bit of the face, a bit of the side. That’s fine for many kinds of science. But it’s not ideal for studying the disc’s inner structure.

Tau 042021 and Oph 163131 are different. From our vantage point, both discs are oriented almost perfectly edge-on. Think of holding a vinyl record up horizontally versus holding it vertically so you see only its thin edge. The edge-on view does something critical: it blocks most of the glare from the central star.

Without that glare, Webb can resolve the faint, fine dust particles that float above and below the disc’s midplane. Dust that would otherwise be washed out by the star’s brilliance suddenly becomes visible, glowing in reflected starlight like a halo.

That’s why ESA described these images as resembling “rainbow-coloured spinning tops in space.” It isn’t just a pretty turn of phrase. The colours and shapes we see are direct clues to what’s happening inside.

Why it matters: Edge-on discs are unique laboratories for studying how dust grains drift and settle. HH 30, another well-known edge-on disc in the dark cloud LDN 1551, is considered the prototype of this class and has been studied with Webb, Hubble, and ALMA together.

What Are We Actually Seeing in Those Colors?

The images weren’t captured with a single camera or a single filter. They combine data from two of Webb’s most powerful instruments: NIRCam (Near Infrared Camera) and MIRI (Mid-Infrared Instrument). Together, they cover wavelengths from about 2 to 21 micrometres.

Each colour in the final image carries specific physical information. Red, orange, and green tones trace different sizes of dust grains, as well as molecules floating in the disc. Among them:

• Molecular hydrogen (H₂) — the most common molecule in the universe
• Carbon monoxide (CO) — a marker of cool gas conditions
• Polycyclic aromatic hydrocarbons (PAHs) — complex organic molecules that show up where ultraviolet light hits the disc surface

The image of Oph 163131 also includes data from the NASA/ESA Hubble Space Telescope, which contributes visible-light observations, mostly showing fine floating dust lit by the central star.

Oph 163131 is enormous. It spans roughly 66 billion kilometres across — that’s several times the width of our entire solar system. Looking at it, you’re seeing something that dwarfs everything we’ve ever known as home.

How Do Planets Actually Form? Step by Step

From a Cloud of Gas to a Rocky World

Planet formation isn’t a single event. It’s a long, slow chain of collisions, mergers, and gravity doing its quiet work across millions — sometimes hundreds of millions — of years.

Here’s how it unfolds:

1. Gravitational collapse: A cloud of gas and dust called a molecular cloud starts to collapse under its own gravity. As it shrinks, it heats up and spins faster — the same way a spinning ice skater speeds up when pulling in their arms.
2. Protostar and disc formation: The collapsing material forms a hot central protostar. The leftover gas and dust settles into a rotating, flattened disc around it.
3. Condensation: As the disc cools, gas turns to solid particles. Close to the star, heavy minerals and metals condense first. Farther out, where it’s cold enough, ice forms too.
4. Accretion into planetesimals: Dust grains collide and stick together, growing into pebbles, then boulders, then bodies roughly 1,000 metres across — called planetesimals. Our solar system once had around 10⁹ of them.
5. Protoplanet growth: Planetesimals keep colliding and merging. Objects as large as the Moon — protoplanets — start to appear. Their gravity pulls in more material.
6. Planet formation: Over tens of millions of years, a handful of protoplanets dominate. The leftovers become asteroids and comets. The gas giants, like Jupiter, form within the first 10 million years, before the star’s radiation blows the remaining gas away.

This is, as far as we know, how our Earth was born. And it’s exactly what Webb is watching happen — right now, in Taurus and Ophiuchus.

What Is That Gap in Oph 163131 Telling Us?

Here’s where things get genuinely exciting. The ALMA data for Oph 163131 reveals something unexpected: a gap in the inner disc. A clean, curved absence of millimetre-sized dust where there should be material.

The most likely explanation? A planet is already forming there. As a young planet grows, its gravity sweeps the dust in its orbital path, carving out a ring-shaped gap. Astronomers call this “gap clearing.” It’s one of the strongest indirect signals we have for a planet’s presence before we can detect the planet itself.

The physics behind this gap involves what’s known as the Hill radius — the distance over which a planet’s gravity dominates the star’s gravity. Any dust or smaller body within that sphere gets pulled toward the young planet.

📐 Hill Radius — Gap Clearing Formular_H = a × ( M_p / 3M_★ )^1/3

r_H = Hill radius — the gravitational sphere of influence of the forming planet
a = semi-major axis — the planet’s orbital distance from the host star
M_p = mass of the forming planet
M_★ = mass of the host star

In plain terms: the heavier the planet and the farther it sits from its star, the wider the gap it carves. The gap we see in Oph 163131’s inner disc is a real-time record of this gravitational sculpting at work.

We don’t yet know the mass of the potential planet hiding in that gap. Uncertainty is part of good science. But the gap’s shape and location give us tight enough constraints to say: something is there, and it’s growing.

How Does ALMA Fit Into the Picture?

Seeing the Millimetre Grains Webb Can’t

Webb sees in infrared. It’s brilliant at detecting tiny dust grains — particles just one micrometre across, roughly the size of a single bacterium. Those small grains float high above the disc’s midplane, carried upward by turbulent gas.

ALMA — the Atacama Large Millimeter/submillimeter Array in Chile — sees something different. It detects millimetre-sized grains, which are much heavier. Those larger grains can’t float. Gravity pulls them down and they settle into the dense, thin midplane of the disc. That narrow, concentrated layer is where planet formation actually kicks into high gear.

Think of it like a snow globe. The fine glitter (small grains, seen by Webb) swirls everywhere. The heavier sand at the bottom (millimetre grains, seen by ALMA) slowly settles into a flat layer. Planets grow from the sand, not the glitter.

When astronomers combine Webb’s infrared sensitivity with ALMA’s radio-wavelength precision — and layer in Hubble’s visible-light images on top — they get a complete, three-dimensional picture of how the disc is structured from top to bottom. No single telescope could do this alone.

Related discovery: In December 2024, ALMA confirmed that in the disc around PDS 70 — a young star with two known planets — a localised clump of dust is accumulating outside the planetary orbits. This suggests that already-formed planets help concentrate material for the next planet. Planetary systems don’t just form once: they keep building.

Why Is Webb’s Growing Legacy So Important?

These two new discs don’t stand alone. Webb has been building a remarkable archive of edge-on protoplanetary disc observations. The system HH 30, in the dark cloud LDN 1551 within the Taurus Molecular Cloud, was featured as Webb’s Picture of the Month in January 2025. It’s considered the prototype of its class — the reference point against which all other edge-on discs are measured.

HH 30 is particularly dynamic. A high-velocity jet of gas shoots out at 90 degrees from the disc plane. A wider, cone-shaped outflow surrounds that jet. And a broad, luminous nebula wraps around everything, lit by the young star buried at the centre. It’s a system in constant, dramatic motion.

By studying HH 30, Tau 042021, Oph 163131, and other discs as a growing collection, astronomers can test the theoretical models of planet formation against a real sample of diverse environments. Some discs are calmer. Some are more turbulent. Some seem to form planets faster.

That diversity matters enormously. Our solar system produced rocky inner planets, icy outer planets, and a belt of asteroids. Another solar system might produce something very different — or nothing at all. Understanding why requires watching as many discs as possible, at as many wavelengths as possible, with as much detail as possible.

Webb was built for exactly this. And it’s only getting started.

Also worth knowing: Recent ALMA research at Sigma Orionis — a cluster bathed in intense ultraviolet radiation — showed that planet formation can happen even in harsh, high-radiation environments. This directly challenges earlier assumptions and suggests planet formation is far more common and resilient than we once thought.

Conclusion: A Universe That’s Always Building

Here’s what we take from all of this. Right now, 450 to 480 light-years away, dust is spinning. Grains are colliding. A gap is forming in a young disc, carved by a planet we haven’t even seen yet. The same slow, violent, patient process that built the ground beneath your feet is happening again — probably a thousand times over across the galaxy, at this exact moment.

Webb didn’t just give us beautiful pictures. It gave us a mirror. When we look at Tau 042021 and Oph 163131, we’re looking at what our solar system looked like roughly 4.6 billion years ago. The questions we ask about those discs are the same questions we’re asking about ourselves.

At FreeAstroScience.com, we believe that staying curious is one of the most important things a person can do. We protect you from misinformation by always grounding our articles in real data, real science, and real peer-reviewed sources. The sleep of reason, as Goya once warned us, breeds monsters. We choose to keep our minds awake.

Keep asking questions. Keep looking up. And come back to FreeAstroScience.com — your trusted place to sharpen your understanding of the cosmos, one article at a time.

📚 References & Sources

1. ESA / NASA / CSA James Webb Space Telescope — Webb Eyes a Pair of Planet-Forming Disks, April 3, 2026. phys.org/news/2026-04-webb-eyes-pair-planet-disks.html
2. ESA — Webb Investigates a Dusty and Dynamic Disc (HH 30), January 31, 2025. esa.int/…/Webb_investigates_a_dusty_and_dynamic_disc
3. ESA — Webb Zooms In on a Dusty Disc (IRAS 04302+2247), 2025. esa.int/…/Webb_zooms_in_on_a_dusty_disc
4. ALMA Observatory — ALMA Reveals the Birthplace of a Planetary System (PDS 70), December 12, 2024. almaobservatory.org/…/alma-reveals-the-birthplace-of-a-planetary-system/
5. NASA Science — How Do Planets Form? science.nasa.gov/exoplanets/how-do-planets-form/
6. University of Michigan / ALMA — ALMA Digs Deeper Into Mystery of Planet Formation, July 4, 2023. news.umich.edu/alma-digs-deeper-into-mystery-of-planet-formation/
7. Las Cumbres Observatory — Planets and How They Formed. lco.global/spacebook/solar-system/planets-and-how-they-formed/
8. SETI Institute / ALMA — Planet Formation in Harsh Environments, January 2025. youtube.com/watch?v=E1SkJFLHP18