astronomy
A new ‘guest star’ will appear in the sky in 2024 − a space scientist explains how nova events work and where to look
The nova explosion in T Coronae Borealis, visible from Earth in 2024, will be a unique celestial event, unlike the supernova of 1054.
Vahe Peroomian, USC Dornsife College of Letters, Arts and Sciences
The stars aren’t fixed and unchanging, unlike what many ancient people thought. Once in a while, a star appears where there wasn’t one before, and then it fades away in a matter of days or weeks.
The earliest record of such a “guest star,” named so by ancient Chinese astronomers, is a star that suddenly appeared in skies around the world on July 4, 1054. It quickly brightened, becoming visible even during the day for the next 23 days.
Astronomers in Japan, China and the Middle East observed this event, as did the Anasazi in what is now New Mexico.
In the second half of 2024, a nova explosion in the star system called T Coronae Borealis, or T CrB, will once again be visible to people on Earth. T CrB will appear 1,500 times brighter than usual, but it won’t be as spectacular as the event in 1054.
I am a space scientist with a passion for teaching physics and astronomy. I love photographing the night sky and astronomical events, including eclipses, meteor showers and once-in-a-lifetime astronomical events such as the T CrB nova. T CrB will become, at best, the 50th brightest star in the night sky – brighter than only half the stars in the Big Dipper. It might take some effort to find, but if you have the time, you’ll witness a rare event.
What is a nova?
In 1572, the famous Danish astronomer Tycho Brahe observed a new star in the constellation Cassiopeia. After reporting the event in his work “De Nova Stella,” or “On the New Star,” astronomers came to associate the word nova with stellar explosions.
Stars, regardless of size, spend 90% of their lives fusing hydrogen into helium in their cores. How a star’s life ends, though, depends on the mass of the star. Very massive stars – those more than eight times the mass of our Sun – explode in dramatic supernova explosions, like the ones people observed in 1054 and 1572.
In lower mass stars, including our Sun, once the hydrogen in the core is exhausted, the star expands into what astronomers call a red giant. The red giant is hundreds of times its original size and more unstable. Eventually, all that is left is a white dwarf – an Earth-sized remnant made up of carbon and oxygen. White dwarves are a hundred thousand times denser than diamond. Unless they’re part of a binary star system, where two stars orbit each other, they slowly fade in brightness over billions of years and eventually disappear from sight.
T CrB is a binary star system – it’s made up of a red giant and a white dwarf, which orbit each other every 228 days at about half the distance between Earth and the Sun. The red giant is nearing the end of its life, so it has expanded dramatically, and it’s feeding material into a rotating disk of matter called an accretion disk, which surrounds the white dwarf.
Matter from the accretion disk, which is made mostly of hydrogen, spirals in and slowly accumulates on the surface of the white dwarf. Over time, this blanket of hydrogen becomes thicker and denser, until its temperature exceeds 18 million degrees Fahrenheit (10 million degrees Celsius).
A nova is a runaway thermonuclear reaction similar to the detonation of a hydrogen bomb. Once the accretion disk gets hot enough, a nova occurs where the hydrogen ignites, gets blown outward and emits bright light.
When will it occur?
Astronomers know of 10 recurrent novae – stars that have undergone nova explosions more than once. T CrB is the most famous of these. It erupts on average every 80 years.
Because T CrB is 2,630 light-years from Earth, it takes light 2,630 years to travel the distance from T CrB to Earth. The nova we will see later this year occurred over 2,000 years ago, but its light will be just reaching us later this year.
The accretion of hydrogen on the surface of the white dwarf is like sand in an 80-year hourglass. Each time a nova occurs and the hydrogen ignites, the white dwarf itself is unaffected, but the surface of the white dwarf is wiped clean of hydrogen. Soon after, hydrogen begins accreting on the surface of the white dwarf again: The hourglass flips, and the 80-year countdown to the next nova begins anew.
Careful observations during its past two novae in 1866 and 1946 showed that T CrB became slightly brighter about 10 years before the nova was visible from Earth. Then, it briefly dimmed. Although scientists aren’t sure what causes these brightness changes, this pattern has repeated, with a brightening in 2015 and a dimming in March 2023.
Based on these observations, scientists predict the nova will be visible to us sometime in 2024.
How bright will it be?
Astronomers use a magnitude system first devised by Hipparchus of Nicaea more than 2,100 years ago to classify the brightness of stars. In this system, a difference of 5 in magnitude signifies a change by a factor of 100 in brightness. The smaller the magnitude, the brighter the star.
In dark skies, the human eye can see stars as dim as magnitude 6. Ordinarily, the visible light we receive from T CrB comes entirely from its red giant, a magnitude 10 star barely visible with binoculars.
During the nova event, the white dwarf’s exploding hydrogen envelope will brighten to a magnitude 2 or 3. It will briefly become the brightest star in its home constellation, Corona Borealis. This maximum brightness will last only several hours, and T CrB will fade from visibility with the naked eye in a matter of days.
Where to look
Corona Borealis is not a prominent constellation. It’s nestled above Bootes and to the west of Ursa Major, home to the Big Dipper, in northern skies.
To locate the constellation, look due west and find Arcturus, the brightest star in that region of the sky. Then look about halfway between the horizon and zenith – the point directly above you – at 10 p.m. local time in North America.
Corona Borealis is approximately 20 degrees above Arcturus. That’s about the span of one hand, from the tip of the thumb to the tip of the pinky, at arm’s length. At its brightest, T CrB will be brighter than all the stars in Corona Borealis, but not as bright as Arcturus. https://www.youtube.com/embed/4FWiaWlMGLg?wmode=transparent&start=0 To find Corona Borealis, locate Arcturus, and then look about a handspan above.
You can also use an interactive star chart such as Stellarium, or one of the many apps available for smartphones, to locate the constellation. Familiarizing yourself with the stars in this region of the sky before the nova occurs will help identify the new star once T CrB brightens.
Although T CrB is too far from Earth for this event to rival the supernova of 1054, it is nevertheless an opportunity to observe a rare astronomical event with your own eyes. For many of us, this will be a once-in-a-lifetime event.
For children, however, this event could ignite a passion in astronomy. Eighty years in the future, they may look forward to observing it once again.
Vahe Peroomian, Professor of Physics and Astronomy, USC Dornsife College of Letters, Arts and Sciences
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/
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In a remarkable demonstration of both the unpredictability of space and the extraordinary capabilities of modern astronomical detection, a small asteroid, designated 2024 UQ, recently made headlines after it struck Earth just hours after being identified. This event, which took place on October 22, 2024, marks the third “imminent impactor” recorded this year, highlighting the continual and often daunting reality of near-Earth objects (NEOs).
Discovered by the Asteroid Terrestrial-impact Last Alert System (ATLAS) in Hawaii, a network of four telescopes dedicated to scanning the night sky for potential collision threats, 2024 UQ was small—measuring only about 3 feet (1 meter) in diameter. While news of an asteroid making contact with Earth can evoke concern, there was no cause for alarm in this instance. The diminutive size of the asteroid meant that it posed very little threat to anything on the ground. In fact, it burned up in the atmosphere over the Pacific Ocean near California, leaving no trace or damage.
However, the swift timeline of events raises critical questions about the effectiveness of our current monitoring systems. The impact occurred just two hours after the initial detection, which meant that by the time data was transmitted to the impact monitoring systems operated by the European Space Agency’s Near-Earth Object Coordination Center, the impact had already taken place. According to their November 2024 newsletter, the ATLAS survey had successfully obtained images identifying the asteroid on a collision trajectory, but due to its position near the edge of two adjacent observational fields, it was not recognized as a significant threat until it was too late.
This incident serves as a reminder of the complexities involved in tracking and predicting the paths of NEOs. While advancements in technology have undoubtedly improved our ability to detect these celestial objects, the circumstances surrounding 2024 UQ showcase the potential for oversights in our monitoring capabilities. Despite this event being minor in scale, it emphasizes the importance of continued investment in space surveillance systems, as well as international collaboration in tracking potential hazards lurking in the vast expanse of space.
As we look forward, this close encounter reaffirms the need for vigilance in our exploration and observation of the cosmos. Each NEO presents an opportunity for learning and growth in our understanding of near-Earth dynamics. While 2024 UQ may have come and gone without incident, it certainly sparks curiosity about what lies ahead in our ongoing quest to safeguard our planet from the skies.
Reference Links:
Asteroid Terrestrial-impact Last Alert System (ATLAS): https://fallingstar.com/
The Danger from Asteroid Impact: https://fallingstar.com/danger.php
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/
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In a striking reminder of the cosmos’s potential threats, NASA has issued a warning about a stadium-sized asteroid hurtling towards Earth at an astonishing speed of 16 kilometers per second. Designated as 2024 RV50, this massive rock measures approximately 710 feet in width and is set to pass our planet on October 18, 2024.
What We Know About 2024 RV50
Discovered relatively recently on September 1, 2024 RV50 belongs to the Apollo group of asteroids, which are known for their orbits that bring them close to Earth. The asteroid takes about 769 Earth days—roughly 2.1 years—to complete its orbit around the Sun, traveling at distances that can reach up to 386 million kilometers from the Sun and coming as close as 105 million kilometers.
NASA’s Jet Propulsion Laboratory (JPL) is diligently monitoring the asteroid’s trajectory using advanced tracking systems. According to current calculations, 2024 RV50 will pass Earth at a distance of approximately 7.42 million kilometers, which may seem far, but in astronomical terms, it’s a close encounter.
Potentially Hazardous?
While 2024 RV50 is classified as a potentially hazardous object due to its size and proximity to Earth, NASA assures us that it does not pose a threat. The risk of any significant impact is minimal, and the asteroid’s current trajectory suggests it will safely pass by our planet. For context, the next encounter with Earth is projected for October 18, 2064, when it will come even closer at a distance of about 5.67 million kilometers.
The Importance of Monitoring Asteroids
NASA’s ongoing efforts to track and monitor asteroids are crucial. These ancient celestial bodies provide insights into the early solar system, as they are remnants of the material that formed planets. Understanding their trajectories and potential impacts is essential for planetary defense, especially since history has shown that asteroid impacts have drastically altered Earth’s biosphere. The infamous asteroid that struck the Yucatán Peninsula 6.5 million years ago is believed to have contributed to the extinction of 75% of Earth’s species, including the dinosaurs.
Through advanced observation techniques and modeling, NASA aims to predict potential threats and develop mitigation strategies. Continuous monitoring of such objects not only helps safeguard our planet but also enriches our understanding of the solar system’s history.
As we prepare for the passing of 2024 RV50, it serves as a reminder of the dynamic nature of our universe and the importance of vigilance in the face of potential cosmic threats. NASA’s commitment to tracking these celestial bodies ensures that we remain informed and prepared for whatever the universe may send our way.
JPL website tracking Asteroid 2024 RV50: https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=2024%20RV50
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/
STM Daily News is a vibrant news blog dedicated to sharing the brighter side of human experiences. Emphasizing positive, uplifting stories, the site focuses on delivering inspiring, informative, and well-researched content. With a commitment to accurate, fair, and responsible journalism, STM Daily News aims to foster a community of readers passionate about positive change and engaged in meaningful conversations. Join the movement and explore stories that celebrate the positive impacts shaping our world.
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astronomy for hobbyist
Chasing Celestial Wonders: Your Guide to Spotting Comet Tsuchinshan-ATLAS
Comet Tsuchinshan-ATLAS is visible tonight after sunset. It’s a rare, long-period comet from the Oort Cloud, best viewed with binoculars against the western horizon.
Greetings, stargazers! If you missed the breathtaking display of the Northern Lights this past Thursday or are simply craving another celestial spectacle, there’s an unmissable show taking place in the night sky right now—Comet Tsuchinshan-ATLAS. Also known as C/2023 A3, this comet has recently made its closest approach to Earth, and it’s treating us with a glorious exhibition as it makes its way across the post-sunset western horizon.
When and Where to Look
Tonight, Sunday, October 13th, is the perfect opportunity for observers in the northern hemisphere to catch a glimpse of Comet Tsuchinshan-ATLAS. Approximately 45 minutes after sunset, keep your eyes peeled toward the western horizon. Although it’s close to reaching its intrinsic brightest, spotting the comet just after sunset could be challenging due to fading twilight. However, don’t let the bright, 83%-lit waxing gibbous moon discourage you, as its brightness won’t interfere with your viewing.
How to Spot the Comet
Using some well-known celestial reference points can help you locate the comet. First, ensure you have a clear view of the western horizon. Find the bright planet Venus and the bright star Arcturus—they will be close to the horizon. Comet Tsuchinshan-ATLAS will be situated slightly below a midpoint between these two brilliant points.
Although you might be able to spot the comet with your naked eyes, a pair of binoculars will enhance your view. The comet will rise a little higher in the sky this weekend compared to previous nights, providing a clearer view. Still, the observing window will be relatively short as the comet will quickly sink below the horizon again.
Upcoming Opportunities
If you’re unable to view the comet tonight, don’t worry. According to Sky & Telescope, the comet-watching conditions will improve as we move into the next week. Monday, October 14th, and Tuesday, October 15th are projected to offer the best viewing experiences since the comet will appear against a darker sky. Be sure to check back for our detailed viewing guides for those nights.
It’s important to note that comets—and weather conditions—can be unpredictable, so take advantage of clear skies whenever possible.
A Glimpse into History
Comet Tsuchinshan-ATLAS is more than just a fleeting celestial visitor; it’s an extraordinary long-period comet that hails from the Oort Cloud, the distant sphere of icy bodies that encircles our solar system. This comet makes an incredibly rare journey into the inner solar system only once every 80,000 years—a historic event to witness!
Discovered in early 2023 by astronomers from China’s Tsuchinshan Observatory, with its presence confirmed by the ATLAS telescope in South Africa, Comet C/2023 A3 represents both scientific curiosity and natural beauty.
Stay tuned to our astronomy section here https://stmdailynews.com/science/astronomy/
If you want more comet news, visit Earth-Sky: https://earthsky.org/astronomy-essentials/visible-planets-tonight-mars-jupiter-venus-saturn-mercury/
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/
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