Another one of those months with small and cute news, September brought us asteroid soil, spinning black holes, nearby black holes, and falling antimatter. Now let’s be less sensational and make sense of each of these.
NASA’s OSIRIS-REx spacecraft met with the asteroid called Bennu in 2020 and collected 250 grams of its soil. It now returned close-ish to Earth — and actually ejected a capsule with the sample from a whopping 100,000 kilometers above ground. The capsule reached California safely and scientists say that its content will be feeding analyses for decades.
Nearby black holes
Scientists from the University of Padua found strong hints for one or more black holes at the stunningly nearby distance of 150 light years from here. More precisely, they checked closely the motions of the Hyades star cluster, in the data of the Gaia space observatory, and concluded that two or three black holes must be in there.
If this gets confirmed it’ll be a nice surprise, as the previously discovered closest black hole, known as Gaia BH1, was at 1,500 light years away. And actually I feel envy for not being the person who came up with the commentary found here: “If, as the ESA described it, Gaia BH1 is ‘in our cosmic backyard,’ then the Hyades black holes are in your fridge rummaging for leftovers.”
Spinning black holes and falling antimatter
The other two pieces of news are about things reasonably expected to happen, but nevertheless observed for the first time only now. One of them is that black holes spin around themselves, a fact now seen in the photogenic M87.
The other is that antimatter should be attracted by gravity the same way usual matter does. Expected, but now also measured, at least for antihydrogen atoms, by the ALPHA experiment at CERN.
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