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Gas Giants vs. Brown Dwarfs: Unraveling the Cosmic Spin Mystery

·21 min·1 clip

Giant planets rotate faster than their brown dwarf lookalikes, according to a new Astronomical Journal study.

Space Time opens with a question about how to tell gas giants from brown dwarves. For years, astronomers have run into the same problem: the two classes can overlap in brightness, temperature, and even atmospheric fingerprints, so through a telescope they can look like an oversized planet or an undersized star. A report in the Astronomical Journal offers a fresh clue. It says giant planets rotate significantly faster than their brown dwarf lookalikes, making spin a possible diagnostic for objects that otherwise blur together. The observations are presented as the clearest evidence yet for that difference. Space Time also points to a nuclear power station on the Moon getting the green light. Then it turns to CryoSat. The satellite had been operating for almost 16 years when it received a remote software upgrade for its platform magnetometer. The magnetometer is an operational instrument, installed to keep the craft at the right attitude and point its science tools toward the right part of Earth's surface. CryoSat's primary mission remains the study of Earth's ice. Its radar measures small changes on the surface of ice sheets and sea ice down to accuracy of just a few millimetres. As part of ESA's Earth Explorer family, it has already produced databases on polar oceans, subglacial lakes, and ice sheets. The upgrade also let it measure changes in Earth's magnetic field. That proved useful when an especially strong X-class solar flare hit Earth on January 18. The flare was caused by an eruption on the Sun's surface. It released huge amounts of energy that reached Earth within 25 hours. Over three days, CryoSat contributed scientific data to measure the intensity of the geomagnetic storm. The storm drove auroral activity at much lower latitudes than usual, with sightings as far north as Sydney.

As heard by us

A spin-rate clue sharpens a long-running astronomy problem, while CryoSat gets pulled into storm duty.

The episode moves with a tidy sense of momentum, starting with a sharp astronomy problem: how to separate gas giants from brown dwarves when brightness, temperature, and atmospheric fingerprints can blur together.

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Why you'd press play

You get a spin clue for telling gas giants from brown dwarves, then a satellite job tied to a powerful geomagnetic storm.

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