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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Hello, stargazers and night sky enthusiasts! If you’ve been waiting for a celestial spectacle to light up the sky this year, look no further than the annual Perseid meteor shower. It’s a highlight each summer, and this year’s show has already begun, promising to offer some of the most breathtaking views yet.

What Makes the Perseids Special?

The Perseid meteor shower, active from late July to late August with a peak around mid-August, is one of the best and most reliable meteor showers of the year. Flying through the sky at a dazzling speed of 37 miles per second, the meteors streak across the night sky, decorating it with their radiant, colorful trails. These trails, or “wakes,” look like glowing lines momentarily etched into the dark canvas of space, creating a spectacle of natural fireworks.

Mark Your Calendars: Peak Viewing Times

This year, the grandest display is anticipated on the morning of August 12th. During the peak, you can expect to see between 50 to 100 meteors per hour. For the best viewing experience, find a spot away from city lights, and look up between midnight and dawn. This timing, when the skies are darkest, promises a clearer view and a greater number of meteors. Don’t worry if you can’t make it on the peak night; the Perseids are known for a strong buildup and you can start watching for meteors as early as the first week of August.

Why They Shine So Brightly

The science behind the spectacle is as fascinating as the visuals. Meteors, often referred to as “shooting stars,” are actually bits of comet debris entering Earth’s atmosphere at extremely high speeds. The Perseids originate from the comet 109P/Swift-Tuttle, which orbits the Sun every 133 years, shedding particles along its path. These particles then collide with Earth’s atmosphere, heating up due to the immense friction, and igniting the fiery trails we see from the ground.

Interestingly, the Perseids are particularly known for their fireballs: larger and more vivid meteors that produce an exceptionally bright and long-lasting display. This makes the Perseids one of the most spectacular meteor showers to observe.

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Look to Perseus

The shower is named “Perseids” because the meteors seem to emerge from the constellation Perseus, helping observers know where to direct their gaze. Gather your friends, set up a cozy spot under the stars, and prepare to be mesmerized by these celestial fireworks.

Tips for Meteor Watchers

To maximize your Perseid experience, consider the following tips:

• Find a dark spot, away from the light pollution of urban areas.
• Bring a reclining chair or a blanket so you can lie back comfortably and look up.
• Allow your eyes about 15-30 minutes to adapt to the darkness for optimal viewing.
• No special equipment is needed, just your eyes, but a pair of binoculars might bring an enhanced view of the sky.
• Check the weather: clear, cloudless skies are best for meteor watching.

The Perseid meteor shower is not just a beautiful natural phenomenon but also a shared celestial event that unites sky watchers around the globe in wonder and excitement. So mark your calendars, and get ready to enjoy one of nature’s most dazzling shows. Whether you’re a novice watcher or a seasoned astronomer, the Perseids are sure to offer a memorable sky gazing experience. Happy meteor hunting!

If you want to learn more about the upcoming meteor showers, check out the link. https://earthsky.org/astronomy-essentials/earthskys-meteor-shower-guide/

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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