Stellar Saturdays · the week's best pictures from off-world

From The Decisional Pass

The prettiest picture released this week is also a receipt for a missing shipment of energy.

The Tarantula, weighed

Released August 11, this is 30 Doradus — the Tarantula Nebula — about 160,000 light-years away in the Large Magellanic Cloud, and the most violent star-forming region anywhere near us. Four telescopes went into the frame: Chandra in X-rays (blue), Hubble in visible hydrogen light (green), and Webb plus the retired Spitzer in the infrared (red).

Layer them and you get a collage. Subtract them and you get an argument.

Here's the argument. The Tarantula's massive stars blow off winds at hundreds of kilometres per second. When those winds slam into the surrounding gas, the shocked gas should heat to millions of degrees and glow in X-rays. So astronomers do the bookkeeping: this many stars, this much wind, therefore this much hot gas.

Chandra keeps finding far less than that.

New work led by Jennifer Rodriguez at Ohio State, published in the Astrophysical Journal, closes the books. The energy isn't missing. It's leaving by three doors at once:

• Leakage — the shells of hot gas aren't sealed. Up to half of it escapes through gaps in the walls.
• Mixing — cold gas gets stirred into hot gas, and the average temperature drops below what X-rays report.
• Conduction — where hot material touches cooler material directly, heat simply walks across the boundary.

None of those three is exotic. Any one of them alone doesn't balance the ledger. All three together do.

I keep thinking about this as a failure-of-imagination story rather than a physics story. For years the shortfall looked like a problem with the stars — maybe the winds were weaker than modelled, maybe the star count was off. It turned out to be a problem with the assumption that the container holds. Once you stop treating the nebula as a sealed vessel, the arithmetic works.

That's an operations lesson dressed as astrophysics. When your numbers don't close, check the boundaries before you check the source.

The eclipse nobody at 400 km got to see properly

Wednesday's total solar eclipse ran from eastern Greenland across western Iceland and into northern Spain — the first totality on mainland Spain since 1905, with a maximum of 2 minutes 18 seconds anywhere on the path. Millions of people were under it. You have seen the ground photos by now.

Here's the frame you probably haven't seen: the same eclipse, from the International Space Station.

NASA astronaut Jessica Meir shot this sequence through the station's window 13 with an 800 mm lens and a 1.4x extender. NASA's own file metadata labels the frames "18 percent coverage from ISS" — and the station's nadir at the time was roughly 37.6° N, 57.4° W, out over the South Atlantic well east of Argentina.

Which is to say: the most expensive observation platform in low Earth orbit got a mediocre seat, because it happened to be over the wrong ocean.

I love this frame for exactly that reason. The ISS orbits at about 7.7 km/s and comes back around every ninety minutes, but the Moon's shadow does not wait for you, and you cannot re-phase an orbit for a photograph. You take the eclipse your ground track gives you. Everyone under that shadow on Wednesday — in Reykjavík, in León, on a boat in the North Atlantic — saw a slightly different eclipse, and so did the crew, and theirs was 18 percent.

Six of the nine frames in this set are just the uneclipsed disc, taken before and after. That's the baseline. Somebody up there was being rigorous about a photograph nobody asked them for.

And one from the surface, worth a second look

This one dropped just before the window, but it deserves the extra week.

Perseverance watched Earth disappear behind Phobos — a composite built from three images taken on 2 July 2026 and released on August 5.

The crescent is Phobos, Mars's larger moon, a lumpy 22-kilometre rock orbiting close enough that it crosses the Martian sky several times a day. The dot is us, roughly 195 million miles off, at the moment before it slid behind.

There's no scientific headline here. There's just the geometry: a robot standing on the floor of an old lake bed, pointing a camera up, and catching the entire human species being briefly occulted by a captured asteroid.

That's the picture of the week for me, and it isn't even the prettiest one.

— Elio

References

• Colorful Views of Nearby Tarantula Nebula — Chandra X-ray Observatory, August 11, 2026
• Three energy-loss routes may explain Tarantula Nebula's X-ray shortfall — Phys.org
• The Tarantula That Lost Its Fire — Universe Today
• ISS075-E-14013, 12 August 2026 — Wikimedia Commons / NASA JSC
• Total Solar Eclipse on August 12, 2026 — NASA Science
• Total solar eclipse 2026 thrills millions — Space.com
• NASA's Perseverance Captures Phobos and Earth (PIA26758) — NASA Science, August 5, 2026

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