Brian Koberlein, Author at Universe Today

November 7, 2024November 7, 2024 by Brian Koberlein

You Can Build a Home Radio Telescope to Detect Clouds of Hydrogen in the Milky Way

The 1-meter dish of a home radio telescope. Credit: Jack Phelps

If I ask you to picture a radio telescope, you probably imagine a large dish pointing to the sky, or even an array of dish antennas such as the Very Large Array. What you likely don’t imagine is something that resembles a TV dish in your neighbor’s backyard. With modern electronics, it is relatively easy to build your own radio telescope. To understand out how it can be done, check out a recent paper by Jack Phelps.

November 5, 2024November 5, 2024 by Brian Koberlein

We Understand Rotating Black Holes Even Less Than We Thought

Illustration of an exotic black hole. Credit: Alex Antropov, via Pixabay

Black holes are real. We see them throughout the cosmos, and have even directly imaged the supermassive black hole in M87 and our own Milky Way. We understand black holes quite well, but the theoretical descriptions of these cosmic creatures still have nagging issues. Perhaps the most famous issue is that of the singularity. According to the classical model of general relativity, all the matter that forms a black hole must be compressed into an infinite density, enclosed within a sphere of zero volume. We assume that somehow quantum physics will avert this problem, though without a theory of quantum gravity, we aren’t sure how. But the singularity isn’t the only infinite problem. Take, for example, the strange boundary known as the Cauchy horizon.

November 5, 2024November 5, 2024 by Brian Koberlein

How Many Additional Exoplanets are in Known Systems?

One thing we’ve learned in recent decades is that exoplanets are surprisingly common. So far, we’ve confirmed nearly 6,000 planets, and we have evidence for thousands more. Most of these planets were discovered using the transit method. though we there are other methods as well. Many stars are known to have multiple planets, such as the TRAPPIST-1 system with seven Earth-sized worlds. But even within known planetary systems there could be planets we’ve overlooked. Perhaps their orbit doesn’t pass in front of the star from our vantage point, or the evidence of their presence is buried in data noise. How might we find them? A recent paper on the arXiv has an interesting approach.

November 4, 2024November 4, 2024 by Brian Koberlein

Another Way to Extract Energy From Black Holes?

Illustration of a powerful black hole and its magnetic field. Credit: L. Calçada/ESO

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.

November 3, 2024November 3, 2024 by Brian Koberlein

Future Space Telescopes Could be Made From Thin Membranes, Unrolled in Space to Enormous Size

Illustration of an array of membrane mirror telescopes. Credit: Sebastian Rabien, Max Planck Institute for Extraterrestrial Physics

Space-based telescopes are remarkable. Their view isn’t obscured by the weather in our atmosphere, and so they can capture incredibly detailed images of the heavens. Unfortunately, they are quite limited in mirror size. As amazing as the James Webb Space Telescope is, its primary mirror is only 6.5 meters in diameter. Even then, the mirror had to have foldable components to fit into the launch rocket. In contrast, the Extremely Large Telescope currently under construction in northern Chile will have a mirror more than 39 meters across. If only we could launch such a large mirror into space! A new study looks at how that might be done.

November 2, 2024November 2, 2024 by Brian Koberlein

Webb Confirms a Longstanding Galaxy Model

JWST image of the grand design spiral galaxy NGC 628. Credit: NASA / ESA / CSA / Judy Schmidt (CC BY 2.0)

Perhaps the greatest tool astronomers have is the ability to look backward in time. Since starlight takes time to reach us, astronomers can observe the history of the cosmos by capturing the light of distant galaxies. This is why observatories such as the James Webb Space Telescope (JWST) are so useful. With it, we can study in detail how galaxies formed and evolved. We are now at the point where our observations allow us to confirm long-standing galactic models, as a recent study shows.

November 1, 2024November 1, 2024 by Brian Koberlein

Will Advanced Civilizations Build Habitable Planets or Dyson Spheres

Artist's impression of the terraforming of Mars, from its current state to a livable world. Credit: Daein Ballard

If there are alien civilizations in the Universe, some of them could be super advanced. So advanced that they can rip apart planets and create vast shells surrounding a star to capture all its energy. These Dyson spheres should be detectable by modern telescopes. Occasionally astronomers find an object that resembles such an alien megastructure, but so far, they’ve all turned out to be natural objects. As best we can tell, there are no Dyson spheres out there.

October 31, 2024October 31, 2024 by Brian Koberlein

Learning More About Supernovae Through Stardust

Illustration of Supernova 1987A based on observations by ALMA. Credit: Alexandra Angelich (NRAO/AUI/NSF)

Most of the diverse elements in the Universe come from supernovae. We are, quite literally, made of the dust of those long-dead stars and other astrophysical processes. But the details of how it all comes about are something astronomers strive to understand. How do the various isotopes produced by supernovae drive the evolution of planetary systems? Of the various types of supernovae, which play the largest role in creating the elemental abundances we see today? One way astronomers can study these questions is to look at presolar grains.

October 31, 2024October 31, 2024 by Brian Koberlein

Astronomers Predict the Orbits of Potentially Hazardous Comets From Meteor Showers

Comets have long been seen as omens and portents, and it’s easy to understand why. They first appear as faint smudges of light in the sky, sometimes fading soon after and sometimes becoming brighter than the planets, with a long, glowing tail. They have been observed throughout human history, but it wasn’t until the eighteenth century that astronomers began to predict the return of some comets. Even today, we can’t predict the return of most comets until after they swing through the inner solar system. If such a comet happens to be heading toward Earth, we wouldn’t know about it until too late. But that could change thanks to our observations of meteor showers.

October 30, 2024October 30, 2024 by Brian Koberlein

Astronomers Have Found the Fastest Spinning Neutron Star

Illustration of a millisecond pulsar consuming material from a companion star. Pulsars that evaporate their companions rather than consuming them could serve as stellar engines. Credit: NASA / GSFC SVS / Dana Berry

Neutron stars are as dense as the nucleus of an atom. They contain a star’s worth of matter in a sphere only a dozen kilometers wide. And they are light-years away. So how can we possibly understand their interior structure? One way would be to simply spin it. Just spin it faster and faster until it reaches a maximum limit. That limit can tell us about how neutron stars hold together and even how they might form. Obviously, we can’t actually spin up a neutron star, but it can happen naturally, which is one of the reasons astronomers are interested in these maximally spinning stars. And recently a team has discovered a new one.