Space · Thursday, 27 August 2026

01 · Briefing · what happened

Seventeen spacecraft tracked one solar eruption. The half aimed at Earth was the half nobody saw.

Space 1 min 23 sources

A cloud of magnetised gas left the Sun in two lopsided lobes. The telescope that watches the Sun full-time saw only the slow one, because the fast one was coming straight at us.

spacecraft that caught the cloud

the previous record was ten [1]

840 km/s

speed of the lobe that hit Earth

the other lobe averaged 534 km/s [1]

2 days

from the Sun to Earth

it erupted on 15 December and arrived on the 17th [1]

0.35 AU

distance of the first detection

about a third of the way out from the Sun, near Mercury [1]

At a glance

A cloud of magnetised gas left the Sun at 00:48 GMT on 15 December 2024, and seventeen spacecraft caught some part of it. [1]
That is a record. The previous best was ten, and those ten sat almost in a line from the Sun out past Earth. [1]
A line of instruments measures timing and speed well. It cannot measure shape, because every one of them looks from the same direction. [1]
Spread wide, the fleet showed two lobes rather than one: a fast lobe aimed at Earth and Mars, and a bigger, slower one off to the side. [1]
SOHO, the telescope that stares at the Sun from near Earth, has watched without a break for over thirty years. It saw only the slower lobe. [1]
The lobe that reached Earth averaged 840 kilometres a second. The other averaged 534, and had slowed to about 400 by the time it passed STEREO-A, a probe that runs ahead of Earth. [1]
Europe's Solar Orbiter sat almost on the Sun-Earth line and detected nothing at all. That silence helped fix the cloud's shape, by ruling out where it was not. [1][2]
The cloud was met near Mercury on 16 December, at Earth on the 17th, at STEREO-A on the 18th and at Mars on the 19th and 20th. [1]
None of the seventeen was built for this. Europa Clipper read it while flying past Mars to borrow speed from the planet, on its way to Jupiter. [1]
A missed cloud costs warning time, and fast ones drive shocks that fling out particles dangerous to anyone outside Earth's magnetic shield, the study's lead author said. [1]
Nobody knows whether lopsided eruptions are common and usually missed, or genuinely rare. Telling those apart needs more instruments away from the Sun-Earth line. [1]
This particular cloud was not strong enough to produce much aurora, the shifting lights seen near the poles. Almost nobody on the ground noticed it. [1]

Forces in play

Blind spot at Earth High→

The main Sun-watching telescope sits on the Sun-Earth line, where a cloud coming straight at us is hardest to measure. [1]

Sideways coverage Building↑

Probes crossing the solar system now double as sensors far off that line. Europa Clipper took a reading on its way to Mars. [1]

Fleet attrition Building↑

The accidental network runs on ageing craft. MAVEN, which caught the cloud at Mars, is already out of service. [1]

Warning time Steady→

Hours of notice matter most for crews beyond Earth's magnetic shield, where there is nothing overhead to soak up the particles. [1]

In play Adrienn Luspay-Kuti, Johns Hopkins Applied Physics Laboratory — led the work that pulled seventeen spacecraft's readings into one picture SOHO — the full-time Sun watcher that saw the wrong lobe Solar Orbiter — the probe whose non-detection narrowed the answer STEREO-A — the sideways viewpoint, ahead of Earth in its orbit Europa Clipper — a Jupiter mission that measured the cloud in passing

How it unfolded

15 Dec 2024 the cloud leaves the Sun at 00:48 GMT
16 Dec met near Mercury, a third of the way out
17 Dec the hidden fast lobe arrives at Earth
18 Dec the slow lobe reaches STEREO-A, ahead of Earth in its orbit
19-20 Dec MAVEN picks it up at Mars
Next Europe plans a probe called Vigil to hold a permanent sideways view

Where this points

Watch whether the next big eruption gets a reading from a probe well off the Sun-Earth line; that is what would show whether lopsided clouds are ordinary.

Also today

9 more stories on this beat.

Roman telescope set to launch Saturday

NASA's Nancy Grace Roman Space Telescope is due to lift off from Kennedy Space Center no earlier than 30 August, on a Falcon Heavy. [3][4][6] One image runs to 300 megapixels. [3]

Why it matters — Its data becomes public as soon as it is processed, so any team can work on it at once. [4][5]
Europe shelves its rocket upgrade

The European Space Agency has put the Ariane 6 Block 3 upgrade on ice, including a lighter carbon upper stage. [7] Governments already subsidise each flight by 32 to 38 million euros. [7]

Why it matters — A planned probe to Saturn's moon Enceladus was counting on it, while Canada spends 2.3 billion dollars over fifteen years building its own. [7][19]
Space Force money spreads out

The Pentagon extended SpaceX's Starshield service across military aircraft without a contest, saying no rival terminal had passed the required aviation tests. [8] LeoLabs won 20.68 million dollars for a movable radar, and SpaceWERX picked 11 firms for deals worth 562.5 million dollars. [9][23]

Why it matters — The government had already spent 51.9 million dollars qualifying SpaceX's terminals, and that spending became the argument against testing anyone else's. [8]
First star stream found outside our galaxy

A former astronomer reading a paper on his phone spotted a faint ribbon of stars beside a dwarf galaxy 115 million light-years away. [10]

Why it matters — Ribbons like it are pulled apart by dark matter, and this is the first one found beyond the Milky Way. [10]
Japan sets a date for Phobos

Japan's MMX spacecraft is set to launch on 19 October, to collect a sample from Phobos, the larger Martian moon, and bring it home. [11]

Why it matters — The same two moons drew two more looks this week: Deimos's dent traced to a single impact, and Perseverance filming Phobos cross the Sun. [12][13][14]
A fifth dish opens at Goldstone

NASA added a 34-metre antenna to its Deep Space Network, the three-site radio system that talks to more than 40 spacecraft. [15]

Why it matters — France's Miratlas is raising 20 million euros to map where skies are clear enough for laser links to orbit. [18]
Spacewalkers fit a faster antenna

NASA's Anil Menon and ESA's Sophie Adenot spent six and a half hours outside the space station installing a high-speed antenna. [16]

Why it matters — It was the third spacewalk this month, with another due in September. [16]
A data centre in orbit buys a guard

Lonestar Data Holdings hired the Polish firm Ares Shield to defend its orbital data centres, in a deal worth up to 6 million dollars. [17]

Why it matters — The chosen weapon is a microwave pulse, because shooting at a satellite would leave debris behind. [17]
Three new looks at galactic engines

Astronomers found 14 galaxies whose vast jets of gas have gone quiet, a first clear look at the engine switching off. [21] A simulation tied central star clusters to the black holes they surround. [22]

Why it matters — A separate paper argues dark stars seeded the first giant black holes, which would explain a faint background hum of ripples in space itself. [20]

02 · Lesson · why it matters

Why the thing on a collision course is the thing that seems to stand still

Shape and speed live in the difference between views, so the observer standing at the target has the worst seat of all.

How it works

One viewpoint gives a time series
A thing coming straight at an observer barely moves across their view
So the seat at the target hides its size and its shape
A second observer, far to the side, sees that motion
And an observer who sees nothing marks where it is not

The twist

The object on course to hit an observer is the one that appears to stay still, which is why sailors watch for the ship whose bearing never changes.

Where you've seen this

Sailing

a vessel holding a steady bearing is on a collision course; the ones drifting across the view will pass

Two eyes

each eye sees a flat picture, and distance comes only from the small difference between them

An outbreak

any one clinic sees an ordinary week, and the shape appears only when many are compared

An argument at home

everyone inside it can see their own part clearly and none of them can see its shape

The catch

More observers do not help if they stand together. Ten probes in a line taught less about shape than a handful spread wide.

And the whole of it

Everyone reads the world from one position, and the shape of a thing is rarely inside any single reading. It sits in the gap between readings, which is why the seat that sees nothing is still worth keeping.

03 · Lab · your turn

Where To Stand

Place three spacecraft around the Sun and feel how shape only appears in the difference between viewpoints.

04 · Truth · what's really going on

Stripped of the framing

The network that watches the Sun was never designed as a network; it is a set of unrelated missions whose scattered positions turned out to be the measurement.

Why it lands — A record number is easy to picture and easy to praise. The finding was not that there were seventeen, but that they stood in different places.

Claimed

What people said. Not yet a fact.

Adrienn Luspay-Kuti, Johns Hopkins Applied Physics Laboratory

Seventeen spacecraft tracked and characterised one eruption, a record, giving an exceptionally detailed view of how it changed. [1]

The count of seventeen includes Solar Orbiter, which took measurements and did not detect the cloud. [1]
The same researcher

A missed cloud means losing warning time, and viewpoints away from the Sun-Earth line will matter more as people travel further out. [1]

Made as the case for future coverage, including a European probe called Vigil that is not yet flying. [1]
NASA

Roman's data will be released as soon as it is processed, so many teams can analyse it at the same time. [4]

The same press kit puts launch no earlier than 30 August, from Kennedy Space Center. [4]
The US Space Force

Only SpaceX can currently meet the requirement for satellite communications on military aircraft. [8]

The finding rests partly on the 51.9 million dollars the government itself spent qualifying SpaceX's terminals. [8]

Verified

What we could actually stand behind.

The cloud arrived as two lobes at different speeds, averaging 840 and 534 kilometres a second. [1]

How we checked — The account names each spacecraft, its distance from the Sun and the date of its detection, so the figures can be checked against the sequence rather than taken whole.
Solar Orbiter detected nothing, sitting almost exactly Earth's distance from the Sun and about ten degrees off the Sun-Earth line. [1][2]

How we checked — The spacecraft and its elongated orbit are described on the mission's own agency page; the non-detection comes from the study. [2]
Roman is set to launch no earlier than 30 August on a Falcon Heavy from Kennedy Space Center. [3][4][6]

How we checked — NASA's press kit, NASA's own media notice and the European Space Agency's mission page all carry the same date.
European governments subsidise each Ariane 6 flight by 32 to 38 million euros, on top of 3.6 billion euros of development. [7]

How we checked — Attributed to the space agency's own director general in a published interview, quoted in the report.

Nobody knows

Open questions — ours included.

Whether lopsided eruptions are common or genuinely rare.

The researcher says this is the open question, and a rare shape cannot be told apart from a poorly watched one without more viewpoints. [1]
What made this cloud lopsided in the first place.

The cause is still being investigated and no explanation has been published. [1]
How much of the lead story rests on a single account.

One outlet in our pool carried this study, and we found no second independent report of the same figures. The named detections are checkable; the framing is one telling.
Whether Europe will pay to build more Ariane 6 rockets.

Ministers are not due to decide until the end of the year, and the agency says it wants clarity by then. [7]

Who gains

Planetary missions in their cruise phase — Their instruments now count as space-weather sensors, which strengthens the case for keeping them running between science phases. [1]
Europe's planned Vigil probe — A demonstrated blind spot on the Sun-Earth line is the clearest argument for a spacecraft that sits off it. [1]
SpaceX — The Space Force ruled that no rival aircraft terminal had passed the required military tests, so the work went to it without competition. [8]
Astronomers with no telescope time — Roman's survey data is released as soon as it is processed, so discoveries can come from anyone reading the archive. [4][10]

Who pays

Crews and aircraft outside Earth's magnetic shield — A cloud nobody saw coming is a cloud nobody had hours to prepare for. [1]
European science missions — Shelving the Ariane 6 upgrade removes a capability some planned probes were relying on, including one aimed at Saturn's moon Enceladus. [7]
Rival satellite communications suppliers — The only alternative terminals had never been tested to the military aviation standards, so they were ruled out on paper rather than in a contest. [8]

05 · Hope · carry this

The instruments that caught this cloud were built by different countries, in different decades, for different questions. They still added up to one clear measurement.