Dropoff (12/15/22)

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Views of a Volcanic Moon

Circling the king of planets is a small spacecraft, armed with a slew of imagers, magnetometers and radiation sensors, sent on a mission to uncover the secrets beneath the swirling clouds. That mission is done, and now the probe, Juno, has turned its attention elsewhere.

Juno completed its core mission to study the clouds and magnetosphere of Jupiter nearly two years ago. Since then, it’s been performing additional science observations of the Galilean moons. It started with the largest, Ganymede, in 2021 and captured the first images of the icy ocean moon Europa in more than two decades earlier this year.

Today, Juno is visiting a new target: Io, the third largest moon of Jupiter and the most volcanic place in the solar system.

Most of what we know about Io comes from the Galileo spacecraft, which performed a series of flybys of the moon between 1995 and 2002. We’ve got that mission to thank for the very ugly, moldy-golf-ball portrait of Io above, depicting the body’s greenish surface in almost true color. Regions of high volcanic activity are marked by brown and red spots.

Since then, three other missions—Ulysses, Cassini, and New Horizons—have visited Io briefly and observed its intense volcanic activity. During its 2007 flyby, New Horizons watched the moon spew out a plume of magma more than 215 miles high.

In the next few years, Juno will expand our understanding of Io, its volcanism, and potentially its magnetic field. The flyby happening today is only the first of nine observations scheduled for the next year and a half. During the closest of these, Juno will draw within 930 miles of the moon’s surface.

Watching Black Holes Grow

At the center of nearly every galaxy lies a supermassive black hole, pulling clouds of gas and stars into the familiar swirling structures we recognize. But for decades, scientists have been trying to understand the relationship between these supermassive black holes and the galaxies they’re surrounded by.

Now, a team of researchers at the University of Arizona say they’ve used machine learning and complex simulations to uncover evidence for how black holes develop and grow.

Looking into the darkness: It’s nearly impossible to discern any details about the structure or past of black hole through direct observations. This is because of the event horizon, or the point of no return for light and matter, which completely surrounds the hole itself. Turning your fancy telescopes towards the center of a galaxy can show you details about the disk of gas and dust surrounding the black hole, but, by definition, they can’t show you anything beyond the event horizon.

That’s where machine learning comes in. The research team used a program called Trinity, which can create millions of different simulated universes that go by different rules. The researchers would input their best guesses for the rules that govern how black holes might form and grow, then watch the program determine what a galaxy obeying such rules might look like. Then, it became a question of picking the results that most closely resembled actual observational data.

“If you put black holes into the simulated galaxies and enter rules about how they grow, you can compare the resulting universe to all the observations of actual black holes that we have," said Haowen Zhang, lead author of the paper, in a press release. "We can then reconstruct how any black hole and galaxy in the universe looked from today back to the very beginning of the cosmos."

The findings: The team’s simulations provided evidence that black holes tend to grow in lockstep with the galaxies that revolve around them. That means that if a galaxy doubles in size, scientists could expect the black hole at its center to double in size as well.

The simulation data also shows that, like galaxies, black holes may grow very quickly at the beginning of their lives, then slow down until they reach a certain point and stop growing completely.

The reasons for this strange balance between galaxies and the supermassive black holes at their centers are still unknown. The team hopes to continue using a similar machine learning approach to uncover more details about the synchronization between black hole and galaxy.

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Other News from the Cosmos

• Orion splashed down last weekend after completing its 26-day mission around the Moon.

• Nature named Jane Rigby, an astronomer who worked on JWST, one of its top 10 contributors to science in 2022.

• The magazine also spotlighted Anthony Tyson, a physicist who pioneered the weak gravitational lensing technique, as one of the top researchers to keep an eye on next year.

• Orphan stars, which live in the vast empty space between galaxies, have become far easier for scientists to observe thanks to a new imaging technique.

• JWST made its first observations of the TRAPPIST-1 system, which contains some of the best candidates we’ve found for potentially habitable worlds.

• Perseverance recorded audio as a Martian dust devil passed overhead.

• Alan Shepard’s famous golf ball didn’t travel for “miles and miles and miles” on the Moon after all—new analysis found that it only flew about 40 yards. (Still, not bad for a one-armed swing in a spacesuit.)

Rachael's Recs

⚛️ Nuclear fusion: Unquestionably, the biggest science news from the last week came from the DOE’s Princeton Plasma Physics Laboratory, which announced that it had achieved ignition in nuclear fusion. Check out Scientific American’s explainer on nuclear fusion ignition to get you up to speed, then head to Space.com, where Leonard David explored what that could mean for the future of spaceflight.

🔭 Where credit is due: The White House is pushing for more transparency in scientific research. By 2025, all federally funded research will be made publicly available. NASA is considering taking this initiative a step further by making all telescope data public immediately after it’s taken…but is that such a good thing? In an op-ed for Scientific American, astronomer Jason Wright argues against this proposed policy. Food for thought.

The View from Space

I don’t think I’ll ever get tired of seeing new shots of the Carina Nebula. This latest image from Hubble captured a region near the center of the nebula in infrared, revealing a field of glittering stars.