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.

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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.

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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.

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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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Last Thursday night, residents across the Midwest and Southeastern U.S. were treated to an extraordinary celestial event that turned the night sky into a spectacular show. At approximately 9:45 p.m. EST, a brilliant flash lit up the heavens, captivating all who saw it. Reports of the phenomenon poured in, with some onlookers describing the sight as akin to “a basketball on fire.”

The Flash

But what exactly was this bright object that seized the attention of hundreds? According to Dr. Wes Ryle, an astronomer at the Cincinnati Observatory, this luminous display was caused by a “fireball” – an exceptionally bright meteor hurtling through the Earth’s atmosphere at incredible speeds. These fireballs are large meteoric events that stand out due to their size and the intense light they emit as they burn through the atmosphere.

Frequent Flyers in Our Skies

Interestingly, Dr. Ryle pointed out that such events are more common than most might think. “This kind of thing actually happens pretty frequently,” he remarked during an interview with WXIX Fox 19. He elaborated that even when there isn’t a meteor shower happening, our planet regularly encounters debris from space, from tiny grains of sand to larger objects like the one witnessed on Thursday.

Fireballs: A Rare Encounter

Although meteors regularly enter Earth’s atmosphere, fireballs are considerably rarer due to their larger size. According to Dr. Ryle, “Fireballs appear brighter as they’re going down because they are larger in size.” This makes fireballs a stunning, if not occasional, spectacle in the night sky. If you missed this event, there’s no need to worry; such occurrences happen every few days to a week. However, the visibility of these events greatly depends on whether they occur over populated areas and at times when people are likely to observe them.

Did You Hear That?

More intriguingly, some fireballs can produce sounds if they explode close enough to the Earth’s surface. From the recent event, 15 out of 177 reports included mentions of a sound associated with the fireball, though Dr. Ryle noted it’s hard to confirm whether these sounds were directly related to the fireball.

Where Do They Go?

Most meteors disintegrate and burn up in the atmosphere, but occasionally, some debris might make it to the ground. “If a fireball is sufficiently big, there’s always that chance that some debris will actually land,” Dr. Ryle explained. While finding meteorites—especially in regions like Ohio, Kentucky, or Indiana—can be challenging due to the terrain, modern technology such as Ring doorbell cameras and traffic cameras can help track these meteorites’ trajectories.

A Marvel, Not a Menace

Despite the dramatic flare-up in the sky, Dr. Ryle reassured that such events are not cause for alarm but rather an exciting natural phenomenon to observe. He encouraged people to appreciate these rare sights as part of the incredible world of astronomy.

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For anyone eager to learn more or who might have captured this moment on camera, the American Meteor Society welcomes reports, videos, and photos on their website. This interaction helps enhance our understanding of these fiery visitors and their journeys through our sky.

In essence, while the term “shooting star” might be a misnomer, the awe-inspiring sight of a meteor blazing through our atmosphere continues to ignite curiosity and wonder about our celestial surroundings.

More about the Thursday Night Flash

https://www.fox19.com/2024/08/23/did-you-see-bright-flash-sky-thursday-night-heres-what-it-was

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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Every year, countless individuals gaze upward, hoping to catch the fleeting brilliance of a shooting star. These dazzling streaks of light are not only breathtaking to behold but also carry with them the secrets of our early solar system. On Shooting Star Day, we celebrate these incredible phenomena by sharing some fascinating facts about meteoroids, meteors, and meteorites.

What is a Shooting Star?

Contrary to the whimsical name, shooting stars are not stars at all. They are actually meteoroids that burn up when they enter Earth’s atmosphere. This fiery entrance causes the bright streak of light in the sky that we find so mesmerizing. If the meteoroid survives its journey through the atmosphere and lands on Earth, it is then classified as a meteorite.

Meteor Shooting Star Facts:

1. Speed and Visibility: Meteors typically blaze through the atmosphere at speeds exceeding 20 km/s (72,000 km/h; 45,000 mph). They become visible around 100 km (62 mi) above the Earth, illuminating the night with their incandescent trails.
2. Frequency: It’s astounding to note that approximately 25 million meteoroids, micrometeoroids, and other space debris enter Earth’s atmosphere daily, adding up to around 15,000 tonnes annually.

Meteoroids, Meteors, and Meteorites:

• Meteoroids are generally smaller than asteroids and range from tiny grains to objects about a meter in size. They roam the interplanetary space and can originate from comets, asteroids, or even from the moon or Mars due to collision impacts.
• Meteors are the visual phenomenon observed when a meteoroid enters the Earth’s atmosphere and burns up, creating a striking light display.
• Meteorites are meteoroids that manage to make it through the atmosphere and reach the Earth’s surface. They can provide invaluable information about the early solar system.

The Fascinating Composition:

Meteoroids are not only rocks; they carry iron, nickel, and other elements. They are primarily categorized into three types based on their composition:

• Iron: Composed mainly of metallic iron-nickel.
• Stone: Silicate minerals dominate these meteoroids, with some containing small round particles called chondrules.
• Stony-iron: A rare combination of metallic and silicate mineral content.

Observing Shooting Stars:

Catching a glimpse of a meteor requires patience and a bit of luck. However, meteor showers, events where numerous meteors are seen emanating from a single point in the sky, provide a spectacular viewing opportunity. These showers occur when Earth passes through the debris left by comets, and some well-known showers include the Perseids and Leonids.

On Shooting Star Day, whether you head out to an open field for unobstructed views or just glance out your city window, remember that you’re witnessing small fragments of cosmic history illuminating our sky. It’s a reminder of the dynamic and ever-changing nature of the universe—a truly magical realization that connects us all under the same starlit canopy.

So tonight, make a wish on a shooting star and celebrate the mysteries and the beauty of our celestial neighborhood. Happy Shooting Star Day! 🌠

https://en.wikipedia.org/wiki/Meteoroid

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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https://stmdailynews.com/category/stories-this-moment