astronomy

St. Croix: Radio Astronomy in the Caribbean

Published

2 years ago

July 29, 2023

Daily News Staff

Newswise — When the morning sun rises over the lands of the United States, it rises first over St. Croix. Located within the Virgin Islands, St. Croix is the easternmost U.S. territory. Originally inhabited by the Igneri and Taino peoples of the indigenous Caribbeans, it was colonized by the Dutch in the 1600s. Over the centuries control of the island passed between several colonial powers before becoming a United States territory in 1917.

Once an agricultural power in the islands, it is now a popular tourist destination. It has a rich culture with a unique island flair. Within the main city of Christiansted, Spanish, Arabic, and Virgin Island Creole can be heard, scattered among the predominant English dialect. From the old but brightly painted buildings at the center of Christiansted to its modern storefronts, the town is a wonderful mix of past and present.

St. Croix is rich with wildlife, often as relaxed as the tourists around them. The outdoor tables of seaside restaurants are visited by iguanas, colorful birds, and even mother hens with their brood. As with its people, much of the island fauna can trace its origin from faraway lands, brought to the island by colonists and traders. With its warm days and cool nights, it’s easy to call the island home.

Because St. Croix marks the easternmost territory of America, it is a perfect location for an antenna of the Very Long Baseline Array (VLBA). The purpose of the VLBA is to observe the radio sky at an extremely high resolution. High enough that it can pinpoint the locations of distant quasars and use them to measure the Earth’s rotation, and even the geological drift of continents. To achieve such precise measurements, the VLBA requires an array of antennas spread as far apart as possible. It currently consists of ten antennas located on the big island of Hawaii, various locations across the continental U.S., and St. Croix. Thanks to St. Croix, the VLBA can achieve a baseline of nearly 9,000 kilometers, giving it the highest resolution of any single radio observatory.

Although the location of St. Croix is perfect for a VLBA antenna, the island poses significant challenges for using and maintaining a radio antenna. The St. Croix dish is located on the eastern side of the island, almost at sea level. So it is constantly bombarded by salt air, ocean rains, and even the occasional tropical storm. The tropical ocean climate is terribly hard on a radio telescope, so the maintenance crew must work hard to protect it from rust and mechanical stress. Data gathered by the antenna must be gathered on data tapes and shipped back to the Very Large Array in New Mexico to be processed.

But one thing the St. Croix antenna has on all the others is the view. Nowhere else does a VLBA dish have an ocean beach view. Nested within the green hills of the eastern shore, the white dish gleams against a brilliant blue sky. It calls St. Croix its home, and if you are lucky enough to visit St. Croix, you’ll understand why.

Source: National Radio Astronomy Observatory, Brian Koberlein, PhD

Author

Daily News Staff

View all posts

Discover more from Daily News

Subscribe to get the latest posts sent to your email.

Related Topics:astronomy National Radio Astronomy Observatory

Up Next

NASA Welcomes Argentina as Newest Artemis Accords Signatory

Don't Miss

Hyundai Motor and Healthy Seas’ Renewed Partnership Dives Deep to Protect Marine Life and Promote a Circular Economy

Daily News Staff

Science

Jets from powerful black holes can point astronomers toward where − and where not − to look for life in the universe

Published

11 hours ago

April 2, 2025

The Conversation

file 20250320 56 5esaam.jpg?ixlib=rb 4.1 — Black holes, like the one in this illustration, can spray powerful jets. S. Dagnello (NRAO/AUI/NSF), CC BY-SA

David Garofalo, Kennesaw State University

One of the most powerful objects in the universe is a radio quasar – a spinning black hole spraying out highly energetic particles. Come too close to one, and you’d get sucked in by its gravitational pull, or burn up from the intense heat surrounding it. But ironically, studying black holes and their jets can give researchers insight into where potentially habitable worlds might be in the universe.

As an astrophysicist, I’ve spent two decades modeling how black holes spin, how that creates jets, and how they affect the environment of space around them.

What are black holes?

Black holes are massive, astrophysical objects that use gravity to pull surrounding objects into them. Active black holes have a pancake-shaped structure around them called an accretion disk, which contains hot, electrically charged gas.

The plasma that makes up the accretion disk comes from farther out in the galaxy. When two galaxies collide and merge, gas is funneled into the central region of that merger. Some of that gas ends up getting close to the newly merged black hole and forms the accretion disk.

There is one supermassive black hole at the heart of every massive galaxy.

Black holes and their disks can rotate, and when they do, they drag space and time with them – a concept that’s mind-boggling and very hard to grasp conceptually. But black holes are important to study because they produce enormous amounts of energy that can influence galaxies.

How energetic a black hole is depends on different factors, such as the mass of the black hole, whether it rotates rapidly, and whether lots of material falls onto it. Mergers fuel the most energetic black holes, but not all black holes are fed by gas from a merger. In spiral galaxies, for example, less gas tends to fall into the center, and the central black hole tends to have less energy.

One of the ways they generate energy is through what scientists call “jets” of highly energetic particles. A black hole can pull in magnetic fields and energetic particles surrounding it, and then as the black hole rotates, the magnetic fields twist into a jet that sprays out highly energetic particles.

Magnetic fields twist around the black hole as it rotates to store energy – kind of like when you pull and twist a rubber band. When you release the rubber band, it snaps forward. Similarly, the magnetic fields release their energy by producing these jets.

A diagram showing an accretion disk and black hole spraying out a jet of particles, surrounded by magnetic field lines. — The accretion disk around a black hole can form a jet of hot, energetic particles surrounded by magnetic field lines. NASA, ESA, and A. Feild (STScI), CC BY

These jets can speed up or suppress the formation of stars in a galaxy, depending on how the energy is released into the black hole’s host galaxy.

Rotating black holes

Some black holes, however, rotate in a different direction than the accretion disk around them. This phenomenon is called counterrotation, and some studies my colleagues and I have conducted suggest that it’s a key feature governing the behavior of one of the most powerful kinds of objects in the universe: the radio quasar.

Radio quasars are the subclass of black holes that produce the most powerful energy and jets.

You can imagine the black hole as a rotating sphere, and the accretion disk as a disk with a hole in the center. The black hole sits in that center hole and rotates one way, while the accretion disk rotates the other way.

This counterrotation forces the black hole to spin down and eventually up again in the other direction, called corotation. Imagine a basketball that spins one way, but you keep tapping it to rotate in the other. The tapping will spin the basketball down. If you continue to tap in the opposite direction, it will eventually spin up and rotate in the other direction. The accretion disk does the same thing.

Since the jets tap into the black hole’s rotational energy, they are powerful only when the black hole is spinning rapidly. The change from counterrotation to corotation takes at least 100 million years. Many initially counterrotating black holes take billions of years to become rapidly spinning corotating black holes.

So, these black holes would produce powerful jets both early and later in their lifetimes, with an interlude in the middle where the jets are either weak or nonexistent.

When the black hole spins in counterrotation with respect to its accretion disk, that motion produces strong jets that push molecules in the surrounding gas close together, which leads to the formation of stars.

But later, in corotation, the jet tilts. This tilt makes it so that the jet impinges directly on the gas, heating it up and inhibiting star formation. In addition to that, the jet also sprays X-rays across the galaxy. Cosmic X-rays are bad for life because they can harm organic tissue.

For life to thrive, it most likely needs a planet with a habitable ecosystem, and clouds of hot gas saturated with X-rays don’t contain such planets. So, astronomers can instead look for galaxies without a tilted jet coming from its black hole. This idea is key to understanding where intelligence could potentially have emerged and matured in the universe.

Black holes as a guide

By early 2022, I had built a black hole model to use as a guide. It could point out environments with the right kind of black holes to produce the greatest number of planets without spraying them with X-rays. Life in such environments could emerge to its full potential. https://www.youtube.com/embed/b7mTVX9IE0s?wmode=transparent&start=0 Looking at black holes and their role in star formation could help scientists predict when and where life was most likely to form.

Where are such conditions present? The answer is low-density environments where galaxies had merged about 11 billion years ago.

These environments had black holes whose powerful jets enhanced the rate of star formation, but they never experienced a bout of tilted jets in corotation. In short, my model suggested that theoretically, the most advanced extraterrestrial civilization would have likely emerged on the cosmic scene far away and billions of years ago.

David Garofalo, Professor of Physics, Kennesaw State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The science section of our news blog STM Daily News provides readers with captivating and up-to-date information on the latest scientific discoveries, breakthroughs, and innovations across various fields. We offer engaging and accessible content, ensuring that readers with different levels of scientific knowledge can stay informed. Whether it’s exploring advancements in medicine, astronomy, technology, or environmental sciences, our science section strives to shed light on the intriguing world of scientific exploration and its profound impact on our daily lives. From thought-provoking articles to informative interviews with experts in the field, STM Daily News Science offers a harmonious blend of factual reporting, analysis, and exploration, making it a go-to source for science enthusiasts and curious minds alike. https://stmdailynews.com/category/science/

Discover more from Daily News

Subscribe to get the latest posts sent to your email.

The Knowledge

The Mystical Glow of the Night Sky: Exploring Zodiacal Light

Zodiacal light, seen before sunrise, is sunlight scattering off interplanetary dust in the zodiacal cloud. It represents a cosmic connection, best viewed in dark, clear locations during specific times of the year.

Published

1 month ago

February 26, 2025

Rod Washington

Have you ever looked up at the night sky and noticed a faint glow, gracefully extending from the horizon in a triangular shape? This enchanting phenomenon is known as zodiacal light, often referred to as “false dawn” when it’s visible just before sunrise. While it may seem like a mere trick of the light, the zodiacal light holds a fascinating story about the universe surrounding our planet.

The Science Behind Zodiacal Light

Zodiacal light is the result of sunlight scattering off interplanetary dust, creating a delicate illumination in the night sky. This dust resides in a thick, pancake-shaped cloud known as the zodiacal cloud, which orbits in the ecliptic plane of our Solar System. Ranging from 10 to 300 micrometers in size, these tiny particles have masses that can span from one nanogram to several micrograms. Together, they contribute to what we see as a soft glow, complementing the natural light of a moonless night.

Interestingly, zodiacal light can be seen most effectively in dark locations, far away from the interference of city lights or moonlight. When conditions are perfect—a clear night with minimal light pollution—this soft glow stretches from the direction of the Sun, gracefully illuminating the darker parts of the sky. It’s most prominent in the western sky during spring after sunset and in the eastern sky during autumn before dawn.

The Origins of Cosmic Dust

The source of the dust that creates zodiacal light has long been a subject of exploration and debate. Initially thought to originate from active comet tails or collisions among asteroids, recent research suggests that a significant portion of the dust comes from the gradual fragmentation of dormant comets, specifically those in the Jupiter-family category.

When comets break apart, they send tiny fragments scattering through space. As these particles eventually disintegrate further due to collisions and space weathering, they continue to replenish the zodiacal dust cloud. This dynamic relationship ensures that our view of zodiacal light is not just a fleeting moment, but a persistent feature of our cosmic environment.

Viewing Zodiacal Light: Tips and Tricks

To catch a glimpse of this celestial beauty, timing and location are crucial. For those in mid-latitude regions, the ideal times to observe zodiacal light are during the evenings in spring and mornings in autumn. Choose a spot far from city lights, under a clear and moonless sky. As twilight fades, lean back, breathe in the fresh evening air, and let your eyes adjust to the darkness.

The sight will often reveal a column of light that appears brighter near the horizon and tilts at an angle parallel to the ecliptic. Often mistaken for a glimpse of the Milky Way, zodiacal light offers a serene reminder of the intricate cosmos we inhabit.

The Connection to Gegenschein

Zodiacal light isn’t the only celestial phenomenon related to interplanetary dust. There’s also the gegenschein, or “counterglow,” which is a faint oval glow seen directly opposite the Sun. This unique aspect of zodiacal light and gegenschein adds depth to our understanding of celestial phenomena and invites us to ponder our place in the universe.

What is false dawn?

A Cosmic Invitation

Zodiacal light is not just a backdrop for the stars; it represents a beautiful, cosmic connection between our planet and the infinity beyond. It serves as a gentle reminder of the fleeting moments in nature—moments that encourage us to pause, look up, and marvel at the intricate dance of light and dust that swirls around us.

So next time you find yourself under a dark sky, take a moment to seek out this enchanting glow. The zodiacal light is waiting, inviting you to experience the magic of our universe. Happy stargazing!

For more information visit these links:

Wikipedia: https://en.wikipedia.org/wiki/Zodiacal_light

Earth-Sky: https://earthsky.org/astronomy-essentials/zodiacal-light-false-dusk-how-to-see-explanation/

Discover more from Daily News

Subscribe to get the latest posts sent to your email.

astronomy

A Celestial Spectacle: Witness the Rare Planetary Parade on February 28

On February 28, 2025, a rare planetary parade will showcase all seven planets aligning in the night sky. This remarkable event won’t occur again until 2040, making it unmissable.

Published

1 month ago

February 21, 2025

Rod Washington

sun and planets in a plantary parade. — Photo by Zelch Csaba on Pexels.com

Planetary Parade

Astronomy enthusiasts and casual stargazers alike have something extraordinary to look forward to at the end of February. For one brief moment, on the evening of February 28, 2025, all seven planets—Mars, Jupiter, Uranus, Venus, Neptune, Mercury, and Saturn—will align in the night sky, creating a captivating planetary parade. This remarkable event marks the last time such an alignment will be visible until 2040, making it an occasion not to be missed.

What to Expect

The planetary parade will unfold shortly after sunset, with each planet showcasing its brilliance against the backdrop of the evening sky. While most of these celestial bodies will shine brighter than even the brightest stars, Uranus and Neptune will likely require binoculars or a telescope for a better view.

Currently, six of the planets are already aligned, but stargazers will have to wait until February 28 for Mercury to make its debut just above the horizon. Dr. Christopher Barnes, a senior lecturer at the University of Derby, explains the visibility details: “Mars will appear in the east, Jupiter and Uranus in the southeast, and Venus, Neptune, and Saturn in the west.”

Viewing Tips

For those wishing to experience this cosmic event, the best time to observe will be just after sunset when the stars begin to appear. Dr. Barnes suggests that even people in urban areas, where light pollution is often an issue, will be able to see most of the planets. However, seeking a location away from city lights will enhance the viewing experience.

The Benefits of Stargazing

Beyond the thrilling visual spectacle, taking time to gaze upon the stars and planets offers numerous benefits for one’s mental and emotional well-being. Dr. Barnes points out that stargazing encourages mindfulness, allowing individuals to detach from the stresses of daily life. “Engaging with the night sky fosters a sense of peace, restoration, and perspective,” he says.

Future Events

After February 28, the next opportunity to see a planetary alignment of five or more planets will occur in late October 2028 and again in February 2034. However, another seven-planet alignment will not be witnessed for another 15 years, making this February a particularly special occasion.

To cater to those unable to view the parade due to unfavorable weather or light pollution, several observatories will provide live streams of the event. This means everyone can partake in this astral celebration from the comfort of their homes.

As we approach February 28, it’s time to mark your calendars for this rare planetary parade. Whether you grab your telescope, plan a trip to a dark-sky location, or tune in to a live stream, don’t miss your chance to witness this extraordinary alignment of the planets, a spectacle that will be remembered long after it fades from view. Prepare to look up and enjoy the wonders of our solar system!

Resources:

Who doesn’t love a parade, especially a planet parade? How and when to see up to 7 planets

Planetary Parade will soon be visible in the evening sky