astronomy

Eventually everything will evaporate, not only black holes

Published

2 years ago

June 13, 2023

Newswise — Recent theoretical research conducted by Michael Wondrak, Walter van Suijlekom, and Heino Falcke from Radboud University has confirmed Stephen Hawking’s assertion regarding black holes, albeit with some nuances. The study reveals that black holes do undergo evaporation over time due to Hawking radiation, but it challenges the previously held belief that the event horizon is the decisive factor. Gravity and the curvature of spacetime also contribute to this radiation. Consequently, all substantial entities in the cosmos, such as stellar remnants, will eventually experience evaporation.

Stephen Hawking utilized a brilliant fusion of quantum physics and Einstein’s theory of gravity to present his argument that the event horizon, the boundary beyond which gravitational forces prevent escape from a black hole, is a site where the spontaneous formation and annihilation of particle pairs takes place. These pairs, consisting of a particle and its antiparticle, briefly emerge from the quantum field before annihilating each other. However, occasionally, one of the particles plunges into the black hole while the other manages to escape. This phenomenon, known as Hawking radiation, would eventually lead to the gradual evaporation of black holes, as postulated by Hawking.

Spiral

In this recent research conducted at Radboud University, scientists delved into the process described above and reexamined the significance of the event horizon. Employing a combination of methodologies from physics, astronomy, and mathematics, they explored the consequences of particle pairs being generated in the vicinity of black holes. The study unveiled a remarkable finding: particles can be created at distances well beyond the traditional notion of the event horizon. Michael Wondrak, one of the researchers involved, remarked, “Our findings demonstrate the existence of a previously unrecognized form of radiation alongside the well-known Hawking radiation.”

Everything evaporates

Van Suijlekom elaborates on the research findings, stating, “We have revealed that the curvature of spacetime significantly contributes to the generation of radiation, even at far distances from a black hole. The tidal forces of the gravitational field already cause separation between the particles in those regions.” The previous belief that radiation could only occur within the confines of the event horizon has been challenged by this study, demonstrating that the presence of the event horizon is not a prerequisite for radiation to occur.

Falcke emphasizes the implications of the study, stating, “Consequently, entities in the universe lacking an event horizon, such as remnants of deceased stars and other sizable objects, exhibit this radiation phenomenon as well. Over an extensive timeframe, this process would lead to the eventual evaporation of everything in the universe, akin to black holes. This revelation not only alters our comprehension of Hawking radiation but also reshapes our perspective on the universe and its future.”

The study was published on 2 June in the leading journal “Physical Review Letters” of the American Physical Society (APS). Michael Wondrak is excellence fellow at Radboud University and an expert in quantum field theory. Walter van Suijlekom is a Professor of Mathematics at Radboud University and works on the mathematical formulation of physics problems. Heino Falcke is an award-winning Professor of Radio Astronomy and Astroparticle Physics at Radboud University and known for his work on predicting and making the first picture of a black hole.

Source: Radboud University Nijmegen

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astronomy for hobbyist

Stargazing Delight: Catch the Ursid Meteor Shower This Sunday Morning!

Published

1 week ago

December 22, 2024

Lynette Young

As we cozy up to the end of another year, a delightful celestial event is gearing up to grace our skies: the Ursid meteor shower! Set to peak in the early morning hours of Sunday, December 22, this final meteor shower of the year offers a charming opportunity for some stargazing, even amidst the hustle and bustle of the holiday season.

A Little Background on the Ursids

Often overshadowed by the more prolific Geminid meteor shower that dazzles us just a week earlier, the Ursids tend to be a quieter affair. This year, their peak aligns perfectly with the winter solstice—the shortest day and longest night of the year. With the celestial display taking place during this time, there’s a unique chance to soak in some twinkling “shooting stars” above a snowy landscape.

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🌌 Don’t miss the Ursid meteor shower this winter solstice! ✨ Bundle up, head outside, and enjoy the shooting stars! #Stargazing #Ursids ♬ original sound – STMDailyNews

Why Aren’t More People Watching?

Despite their charm, the Ursids are the least observed meteor shower, largely because of the busy holiday season and often unfavorable weather in the Northern Hemisphere—think cold nights filled with clouds. But if you missed the Geminids, fear not! The Ursids provide a wonderful pre-Christmas stargazing treat that is worth a look.

What to Expect from the Ursids

While the Ursids are not renowned for their activity—often delivering a mere 5 to 10 meteors per hour on a good night—there’s still magic in the unpredictability of astronomy. In years past, this meteor shower has surprised us with spectacular displays. Back in 1945 and 1968, observers saw around 100 meteors per hour, while the 1973 shower brought forth about 30 meteors! You never know when the Ursids may decide to put on a show, so keeping your eyes trained on the heavens could lead to some delightful surprises.

Understanding the Ursid Origin

The Ursids get their name from their radiant point in the sky, located in the constellation Ursa Minor, affectionately known as the Little Dipper. What we see as shooting stars are actually small fragments from the comet 8P/Tuttle, which Earth passes through each year. As the debris from the comet enters our atmosphere, it burns up and creates stunning streaks of light against the nighttime backdrop.

Tips for Optimal Viewing

So, how can you maximize your chances of catching the Ursid meteor shower this Sunday?

When to Watch: The Ursids run from December 17 to December 26, with the best viewing time occurring in the predawn hours of December 22. This is when the radiant is highest in the sky, offering the best chance to see those elusive meteors.
Find a Dark Spot: Get as far away from city lights as possible. A clear, dark sky will make it much easier to see the meteors.
Be Patient: Give your eyes time to adjust to the darkness—about 20 minutes is ideal. Bring a comfortable blanket or chair to sit back and enjoy the show.
Check the Weather: Clear skies are essential! Keep an eye on your local weather conditions to ensure a pleasant viewing experience.
Bring a Friend: Stargazing is always more fun when shared! Grab a friend or family member to join you, bringing some hot cocoa for added warmth and comfort.

As you bundle up and head outside this Sunday morning, remember to take a moment to appreciate the vastness of the universe above us. The Ursids may be a modest display compared to their more boisterous meteor shower counterparts, but each little shooting star tells a story of cosmic wonder and beauty. Happy stargazing, and may your sky be filled with twinkling lights! ✨

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Space and Tech

NEOWISE, the NASA mission that cataloged objects around Earth for over a decade, has come to an end

Published

2 weeks ago

December 15, 2024

The Conversation

Toshi Hirabayashi, Georgia Institute of Technology and Yaeji Kim, University of Maryland

The NASA project NEOWISE, which has given astronomers a detailed view of near-Earth objects – some of which could strike the Earth – ended its mission and burned on reentering the atmosphere after over a decade.

On a clear night, the sky is full of bright objects – from stars, large planets and galaxies to tiny asteroids flying near Earth. These asteroids are commonly known as near-Earth objects, and they come in a wide variety of sizes. Some are tens of kilometers across or larger, while others are only tens of meters or smaller.

On occasion, near-Earth objects smash into Earth at a high speed – roughly 10 miles per second (16 kilometers per second) or faster. That’s about 15 times as fast as a rifle’s muzzle speed. An impact at that speed can easily damage the planet’s surface and anything on it.

Impacts from large near-Earth objects are generally rare over a typical human lifetime. But they’re more frequent on a geological timescale of millions to billions of years. The best example may be a 6-mile-wide (10-kilometer-wide) asteroid that crashed into Earth, killed the dinosaurs and created Chicxulub crater about 65 million years ago.

Smaller impacts are very common on Earth, as there are more small near-Earth objects. An international community effort called planetary defense protects humans from these space intruders by cataloging and monitoring as many near-Earth objects as possible, including those closely approaching Earth. Researchers call the near-Earth objects that could collide with the surface potentially hazardous objects.

NASA began its NEOWISE mission in December 2013. This mission’s primary focus was to use the space telescope from the Wide-field Infrared Survey Explorer to closely detect and characterize near-Earth objects such as asteroids and comets.

NEOWISE contributed to planetary defense efforts with its research to catalog near-Earth objects. Over the past decade, it helped planetary defenders like us and our colleagues study near-Earth objects.

An illustration of the WISE spacecraft, which looks like a metal cylinder with a solar panel attached. — NASA’s NEOWISE mission, the spacecraft for which is shown here, surveyed for near-Earth objects. NASA/JPL-Caltech

Detecting near-Earth objects

NEOWISE was a game-changing mission, as it revolutionized how to survey near-Earth objects.

The NEOWISE mission continued to use the spacecraft from NASA’s WISE mission, which ran from late 2009 to 2011 and conducted an all-sky infrared survey to detect not only near-Earth objects but also distant objects such as galaxies.

The spacecraft orbited Earth from north to south, passing over the poles, and it was in a Sun-synchronous orbit, where it could see the Sun in the same direction over time. This position allowed it to scan all of the sky efficiently.

The spacecraft could survey astronomical and planetary objects by detecting the signatures they emitted in the mid-infrared range.

Humans’ eyes can sense visible light, which is electromagnetic radiation between 400 and 700 nanometers. When we look at stars in the sky with the naked eye, we see their visible light components.

However, mid-infrared light contains waves between 3 and 30 micrometers and is invisible to human eyes.

When heated, an object stores that heat as thermal energy. Unless the object is thermally insulated, it releases that energy continuously as electromagnetic energy, in the mid-infrared range.

This process, known as thermal emission, happens to near-Earth objects after the Sun heats them up. The smaller an asteroid, the fainter its thermal emission. The NEOWISE spacecraft could sense thermal emissions from near-Earth objects at a high level of sensitivity – meaning it could detect small asteroids.

But asteroids aren’t the only objects that emit heat. The spacecraft’s sensors could pick up heat emissions from other sources too – including the spacecraft itself.

To make sure heat from the spacecraft wasn’t hindering the search, the WISE/NEOWISE spacecraft was designed so that it could actively cool itself using then-state-of-the-art solid hydrogen cryogenic cooling systems.

Operation phases

Since the spacecraft’s equipment needed to be very sensitive to detect faraway objects for WISE, it used solid hydrogen, which is extremely cold, to cool itself down and avoid any noise that could mess with the instruments’ sensitivity. Eventually the coolant ran out, but not until WISE had successfully completed its science goals.

During the cryogenic phase when it was actively cooling itself, the spacecraft operated at a temperature of about -447 degrees Fahrenheit (-266 degrees Celsius), slightly higher than the universe’s temperature, which is about -454 degrees Fahrenheit (-270 degrees Celsius).

The cryogenic phase lasted from 2009 to 2011, until the spacecraft went into hibernation in 2011.

Following the hibernation period, NASA decided to reactivate the WISE spacecraft under the NEOWISE mission, with a more specialized focus on detecting near-Earth objects, which was still feasible even without the cryogenic cooling.

During this reactivation phase, the detectors didn’t need to be quite as sensitive, nor the spacecraft kept as cold as it was during the cryogenic cooling phase, since near-Earth objects are closer than WISE’s faraway targets.

The consequence of losing the active cooling was that two long-wave detectors out of the four on board became so hot that they could no longer function, limiting the craft’s capability.

Nevertheless, NEOWISE used its two operational detectors to continuously monitor both previously and newly detected near-Earth objects in detail.

NEOWISE’s legacy

As of February 2024, NEOWISE had taken more than 1.5 million infrared measurements of about 44,000 different objects in the solar system. These included about 1,600 discoveries of near-Earth objects. NEOWISE also provided detailed size estimates for more than 1,800 near-Earth objects.

Despite the mission’s contributions to science and planetary defense, it was decommissioned in August 2024. The spacecraft eventually started to fall toward Earth’s surface, until it reentered Earth’s atmosphere and burned up on Nov. 1, 2024.

NEOWISE’s contributions to hunting near-Earth objects gave scientists much deeper insights into the asteroids around Earth. It also gave scientists a better idea of what challenges they’ll need to overcome to detect faint objects.

So, did NEOWISE find all the near-Earth objects? The answer is no. Most scientists still believe that there are far more near-Earth objects out there that still need to be identified, particularly smaller ones.

An illustration showing the NEO Surveyor craft, which looks like a small box with a square lens and a satellite dish, floating through space — An illustration of NEO Surveyor, which will continue to detect and catalog near-Earth objects once it is launched into space. NASA/JPL-Caltech/University of Arizona

To carry on NEOWISE’s legacy, NASA is planning a mission called NEO Surveyor. NEO Surveyor will be a next-generation space telescope that can study small near-Earth asteroids in more detail, mainly to contribute to NASA’s planetary defense efforts. It will identify hundreds of thousands of near-Earth objects that are as small as about 33 feet (10 meters) across. The spacecraft’s launch is scheduled for 2027.

Toshi Hirabayashi, Associate Professor of Aerospace Engineering, Georgia Institute of Technology and Yaeji Kim, Postdoctoral Associate in Astronomy, University of Maryland

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 exploring advancements in medicine, astronomy, technology, or environmental sciences, our science section strives to illuminate 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/

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A Close Encounter: Asteroid 2006 WB Zooms Past Earth Tomorrow

Published

1 month ago

November 26, 2024

Rod Washington

As we gaze up at the night sky, pondering the vastness of the universe, an intriguing event is set to unfold: a football field-sized asteroid is making its way past Earth tomorrow. Named 2006 WB, this celestial traveler is estimated by NASA’s Jet Propulsion Laboratory (JPL) to be about 310 feet across, although its size could range anywhere from 240 to 525 feet. For perspective, a football field measures approximately 360 feet in width, making this asteroid a formidable presence as it skims by our planet.

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Approaching Asteroid

At a distance of 554,000 miles—roughly twice the distance to the Moon—2006 WB will pass by us at a speed of about 4.2 km/s, or approximately 9,400 mph. This velocity is several times faster than a bullet fired from a rifle, which can travel up to around 2,700 mph. While 554,000 miles may sound distant, it is remarkably close on a solar system scale, especially when compared to our neighboring planet Venus, which can be about 24 million miles away at its closest approach.

In addition to 2006 WB, there are four other asteroids making their own close passes in the coming days. Today, two bus-sized asteroids, 2024 WF2 and 2024 WJ3, will soar past Earth at distances of 1,780,000 miles and 2,780,000 miles, respectively. Following them, the plane-sized 2009 WB105 will come within 3,600,000 miles, and on Tuesday, another bus-sized asteroid, 2024 WD3, will pass at around 1,080,000 miles.

Jay Tate, director of the United Kingdom’s Spaceguard Centre observatory, highlights that asteroids are frequently zipping past Earth, often without much public awareness. 2006 WB falls into the category of Near-Earth Objects (NEOs), defined as objects that come within 30 million miles of our planet. NEOs are monitored closely, with over 34,000 identified in our solar system, and the JPL’s Center for Near-Earth Object Studies (CNEOS) actively tracking at least 2,300 potentially hazardous asteroids (PHAs).

While the odds of a large asteroid impacting Earth are exceedingly low, the consequences of such an event could be catastrophic. Svetla Ben-Itzhak, an assistant professor of space and international relations at Johns Hopkins University, warns that a cosmic body of 460 feet in diameter could obliterate an entire city and wreak regional havoc. In contrast, larger objects exceeding 1 kilometer in diameter could have far-reaching global implications, potentially leading to mass extinction.

Fortunately, the asteroids currently making their approach, including 2006 WB, do not fall within the category of potentially hazardous objects due to their size and the distances they will maintain from our planet. As we continue to advance our understanding of these celestial bodies, the importance of tracking and monitoring NEOs remains paramount for the safety of humanity.

As we prepare for the close encounter with 2006 WB, let us appreciate the wonders of our universe and the ongoing efforts of scientists and astronomers dedicated to keeping watch over our cosmic neighborhood. Stay tuned for more updates as we witness the majestic dance of these asteroids in the sky above.