Astronomy

Zinc nanoparticles, a common sunscreen ingredient, can make plants more resilient to climate change – in a surprising way

India plans to launch astronauts to Earth orbit no sooner than 2026, roughly a year past the previously known timeline, following a series of uncrewed flight tests slated to begin in December.

A surprising reversal of our usual understanding of the second law of thermodynamics shows that it may be possible for heat to move in the “wrong” direction, flowing from a cold area to a warm one

A surprising reversal of our usual understanding of the second law of thermodynamics shows that it may be possible for heat to move in the “wrong” direction, flowing from a cold area to a warm one

In a rare show of openness about the X-37B, Boeing Space released a video detailing how the space plane's aerobraking maneuvers help change the spacecraft's orbit.

There are four Americans currently living in space, and each has had the opportunity to add their voice to the more than 160 million other Americans able to participate in the 2024 Presidential election.

Although the COP16 summit in Colombia ended with some important agreements, countries still aren’t moving fast enough to stem biodiversity loss

Although the COP16 summit in Colombia ended with some important agreements, countries still aren’t moving fast enough to stem biodiversity loss

Famous people who die at age 27, such as Janis Joplin, Jimi Hendrix and Amy Winehouse, get even more famous because of the mythology surrounding that number—an example of how modern folklore emerges

Microgravity makes water do weird and wonderful things. NASA astronaut Don Pettit took advantage of that fact to create a colorful ball that resembles Jupiter.

Thousands of homes in Navajo and other tribal lands don’t have access to electricity. A $200-million federal funding effort aims to fix that problem with solar power and other clean energy

The Space Shuttle Atlantis returned to work after a refurbishing and a two-year layoff, as liftoff for the mission occurred on Nov. 3, 1994. Five NASA astronauts and an ESA (European Space Agency) astronaut were aboard for the Atmospheric Laboratory for Applications and Science (ATLAS-3) mission.

The gravitational field of a rotating black hole is powerful and strange. It is so powerful that it warps space and time back upon itself, and it is so strange that even simple concepts such as motion and rotation are turned on their heads. Understanding how these concepts play out is challenging, but they help astronomers understand how black holes generate such tremendous energy. Take, for example, the concept of frame dragging.

Black holes form when matter collapses to be so dense that spacetime encloses it within an event horizon. This means black holes aren’t physical objects in the way they are used to. They aren’t made of matter, but are rather a gravitational imprint of where matter was. The same is true for the gravitational collapse of rotating matter. When we talk about a rotating black hole, this doesn’t mean the event horizon is spinning like a top, it means that spacetime near the black hole is twisted into a gravitational echo of the once rotating matter. Which is where things get weird.

Suppose you were to drop a ball into a black hole. Not orbiting or rotating, just a simple drop straight down. Rather than falling in a straight line toward the black hole, the path of the ball will shift toward an orbital path as it falls, moving around the black hole ever faster as it gets closer. This effect is known as frame dragging. Part of the “rotation” of the black hole is transferred to the ball, even though the ball is in free fall. The closer the ball is to the black hole, the greater the effect.

This view of the M87 supermassive black hole in polarized light highlights the signature of magnetic fields. (Credit: EHT Collaboration)

A recent paper on the arXiv shows how this effect can transfer energy from a black hole’s magnetic field to nearby matter. Black holes are often surrounded by an accretion disk of ionized gas and dust. As the material of the disk orbits the black hole, it can generate a powerful magnetic field, which can superheat the material. While most of the power generated by this magnetic field is caused by the orbital motion, frame dragging can add an extra kick.

Essentially, a black hole’s magnetic field is generated by the bulk motion of the accretion disk. But thanks to frame dragging, the inner portion of the disk moves a bit faster than it should, while the outer portion moves a bit slower. This relative motion between them means that ionized matter moves relative to the magnetic field, creating a kind of dynamo effect. Thanks to frame dragging, the black hole creates more electromagnetic energy than you’d expect. While this effect is small for stellar mass black holes, it is large enough for supermassive black holes that we might see the effect in quasars through gaps in their power spectrum.

Reference: Okamoto, Isao, Toshio Uchida, and Yoogeun Song. “Electromagnetic Energy Extraction in Kerr Black Holes through Frame-Dragging Magnetospheres.” arXiv preprint arXiv:2401.12684 (2024).

The post Another Way to Extract Energy From Black Holes? appeared first on Universe Today.

Jupiter has dozens of moons. Four of them in particular are of interest to planetary scientists.

What was Kylo Ren up to between "The Last Jedi" and "The Rise of Skywalker?" Marvel's new comic book series has the answers.

Don't miss the Taurid meteor shower peak with colorful fireballs and shooting stars this week

From seed oils to olive oil, we now have an overwhelming choice of what to cook with. Here’s how they all stack up, according to the scientific evidence

From seed oils to olive oil, we now have an overwhelming choice of what to cook with. Here’s how they all stack up, according to the scientific evidence

With both Alien and Predator back in action, here's what we can learn from their first big-screen crossover two decades ago.

Mars' global magnetic field may have hung around for 200 million years longer than scientists had thought, possibly giving life a longer window to take hold on the Red Planet.