Theo Marlow

A Gas Giant Bigger Than Jupiter, Built Almost Hollow Put Jupiter next to its closest known rival for sheer size, and Jupiter loses. The rival, a planet called HAT-P-67 b, has puffed its atmosphere out past Jupiter’s edge and kept going, while carrying less than half of Jupiter’s mass. A planet built big and left … Read more

XO-6 b: A Gas Giant That Would Float Picture a planet with roughly 1,398 times Earth’s mass that would still float if you dropped it into an ocean big enough to hold it. That’s XO-6 b, a gas giant found by the transit method in December 2016. The mass behind that claim isn’t a clean … Read more

A Planet Built Like Packing Foam, Or Maybe Not Pull a block of packing foam out of a shipping box, the kind that crumbles a little before you toss it in the recycling bin. That foam runs about 30 to 50 kilograms per cubic meter (kg/m³), light enough that a block the size of a … Read more

The Planet That Swings Like a Comet Most planets keep close to a circle. This one dives toward its star, swings back out almost to where it started, then repeats the loop, a shape that looks far more like a comet’s path than a planet’s lane. The object is TIC 241249530 b, and its orbital … Read more

A Beach Ball That Would Float Drop a beach ball into a backyard pool and it doesn’t sink. It rides high, mostly out of the water, because there’s almost nothing inside it. Now imagine a planet built the same way: a radius about 2.1 times Jupiter’s, wide enough to count among the giants, yet so … Read more

Kepler-1547 b: A Year Shorter Than a Single Earth Day Somewhere, a full year passes before a single day and night on Earth has run its course. That somewhere is Kepler-1547 b, a small terrestrial planet that NASA’s Kepler space telescope caught crossing its star’s face, announced in 2016. The measuring stick: an orbit under … Read more

The Giant Planet That Would Float Drop TOI-791 b into an ocean big enough to hold it, and it would bob on the surface like a beach ball. The planet’s bulk density works out to about 38 kilograms per cubic meter (38 ± 8 kg/m³), according to the team that confirmed it in 2026. Water … Read more

A Planet That Would Float Picture a world with about eight and a half times Jupiter’s mass, then picture it so puffed up that it would float if you could find a bathtub large enough to hold it. HD 100546 b’s modeled bulk density works out to roughly 2 lb/ft³ (32.1 kg/m³). Mass that big … Read more

The Gas Giant Whose Dayside Nearly Melts Tungsten Picture a planet the width of Jupiter, pulled so close to its star that its dayside runs at 3,353 K, a hair below the melting point of tungsten, the toughest-melting metal there is, and about 58% as hot as the Sun’s own surface. That’s WASP-189 b, and … Read more

A Gas Giant a Third as Dense as Earth A planet carrying more mass than Jupiter can still come out only about a third as dense, on average, as Earth itself. That’s K2-31 b, a gas giant confirmed in November 2016 using data from NASA’s K2 space mission. Divide its mass by its volume and … Read more