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Howdy stargazers and welcome to this episode of Star Trails.

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I'm Drew and I'll be your guide to the night sky for the week starting March the 2nd through

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the 8th.

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This week Mercury makes its presence known on the western horizon.

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We check in with the Blaze Star and with recent talk of a potential asteroid collision with

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Earth, spoiler alert, it's not going to hit us.

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We'll take a detailed look at space rocks, their dangers, and what can be done about them.

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So grab a comfortable spot under the night sky and let's get started.

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We begin the week with a beautiful crescent moon in the western sky, just three days past

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new, glowing at about 10% illumination on the evening of March 2nd.

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By March 7th the moon reaches its first quarter phase making it a perfect target for binoculars

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or a small telescope as its craters and mountain ranges cast dramatic shadows along the terminator line.

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Planets are putting on a show this week too.

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Venus now in retrograde will shine brilliantly in the western evening sky after sunset and on March

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the 2nd it will form a stunning pairing with the crescent moon.

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So be sure to step outside and catch that celestial duo.

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Meanwhile, Mercury is making a rare and fleeting appearance, reaching its greatest eastern elongation

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on March 8th, meaning it will be at its best visibility for this period.

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Look low on the western horizon shortly after sunset and you just might spot this elusive inner planet.

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We still have our eyes on T Corona Borealis, a star system that could erupt into a rare nova

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at any moment.

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This binary star located in the constellation Corona Borealis goes nova roughly once every 80 years,

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meaning it might become visible to the naked eye for the first time since 1946.

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Known as the blaze star, T Corona Borealis is expected to brighten from a dim magnitude of 10

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which isn't visible to the naked eye to magnitude 2 which is as bright as Polaris.

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Today we're talking about space rocks, asteroids, comets, meteors, and everything in between.

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You might have heard the recent buzz about asteroid 2024 YR-4,

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which briefly made headlines when early observations suggested a slim chance it could hit Earth in 2032.

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Of course, more recent calculations ruled that out, reducing the risk to almost zero.

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But it got me thinking, what else is out there, flying through space, occasionally paying our planet a visit?

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From the massive asteroid that wiped out the dinosaurs to the Tunguska explosion that flattened a forest in Siberia,

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these space rocks have shaped Earth's history.

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And speaking of dramatic impacts, we can't forget Comet Shoemaker-Levy-9, which slammed into Jupiter in 1994,

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giving us front-row seats to a cosmic collision of epic proportions.

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So let's break it all down. What are these objects? Where do they come from? And should we be worried about them?

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First up, asteroids.

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Asteroids are rocky leftovers from the early solar system, basically the building blocks that never quite became planets.

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Most of them orbit in the asteroid belt, a vast region between Mars and Jupiter that's home to millions of these space rocks.

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Ranging from tiny pebbles to giant bodies hundreds of miles wide.

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Some famous asteroids include Ceres and Vesta, which NASA's Dawn spacecraft studied up close.

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Ceres is particularly interesting because it's large enough to be classified as a dwarf planet.

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And scientists suspect it may have a subsurface ocean, hinting at the possibility of past or present life.

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To learn more about Ceres, go back and check out Episode 46.

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While most asteroids stay put in the asteroid belt, some venture closer to Earth.

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These are called Near-Earth Objects, or NEOs.

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This includes asteroids like Apophis, which once sparked fears of a collision in 2029,

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though we now know it will safely pass by.

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That brings us back to 2024, why are for?

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When it was first discovered, its orbit was uncertain and there was a slim chance it could impact Earth.

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But thanks to follow-up observations, astronomers refined its trajectory and ruled out any danger for now.

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That's exactly why space agencies like NASA and the European Space Agency tracked thousands of NEOs.

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Ready to sound the alarm if one gets too close.

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Space rocks hit Earth's atmosphere every day, but most of the time they burn up as meteors, what we call shooting stars.

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But sometimes they're big enough to cause real damage.

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The most famous example is the Tunguska event of 1908, when a meteor, probably 60 to 100 meters wide,

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entered Earth's atmosphere over Siberia and exploded 3 to 6 miles above the ground.

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The blast flattened 800 square miles of forest with an energy release similar to a nuclear bomb.

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For years, this event was a mystery.

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No impact crater was ever found because the object exploded in mid-air.

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A phenomenon called an air burst.

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If this had happened over a major city, the destruction would have been unimaginable.

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Now, fast forward to 2013, when something eerily similar happened over Chelyabinsk, Russia.

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A 20 meter wide meteor entered the atmosphere at more than 40,000 miles per hour.

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Creating a brilliant fireball that was briefly brighter than the sun.

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Almost 30 kilometers above the city, it exploded with the force of 30 atomic bombs,

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shattering windows and damaging buildings across six Russian cities.

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Unlike Tunguska, this event was caught on thousands of dash cams,

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giving us an unprecedented look at a real-life meteor explosion.

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The shock wave injured 1,500 people, mostly from shattered glass,

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serving as a stark reminder that even small space rocks can pack a serious punch.

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The most infamous asteroid impact in history that we know of was the one that made the dinosaurs extinct.

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66 million years ago, an asteroid roughly 6 miles wide slammed into what is now the year of the 19th century.

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The impact created a crater, an enormous scar over 90 miles across.

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The explosion released as much energy as 10 billion Hiroshima bombs.

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It triggered tsunamis, wildfires and a global dust cloud that blocked out the sun, causing temperatures to plummet.

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In the aftermath, nearly 75% of the earth's surface was destroyed.

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In the aftermath, nearly 75% of all life on earth, including the dinosaurs, went extinct.

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This single event reshaped evolution, clearing the way for mammals and eventually us to take over.

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And here's the wild part.

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Impacts of this magnitude aren't just ancient history. They could happen again.

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Scientists estimate that asteroids large enough to cause global devastation hit earth every few million years.

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Through the years, NASA has studied ways to alter the course of asteroids.

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The most successful test of this has been the DART mission.

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DART stands for Double Asteroid Redirection Test.

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And in 2022, it became the first ever attempt to intentionally alter the trajectory of an asteroid.

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The target was a small asteroid called Dimorphos, which orbits a larger asteroid named Dytamos.

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Neither of these were a threat to earth, but they made the perfect test case for an asteroid deflection experiment.

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NASA launched the DART spacecraft, a small probe about the size of a refrigerator,

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and sent it crashing into Dimorphos at more than 14,000 miles per hour.

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The idea was simple. If we could hit the asteroid hard enough, we could change its orbit just slightly.

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And it worked.

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Before impact, Dimorphos took 11 hours and 55 minutes to orbit Dytamos.

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After the collision, that orbit shortened by 32 minutes, a much bigger change than scientists expected.

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So how do we actually move an asteroid?

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It comes down to momentum transfer, essentially a cosmic game of billiards.

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When DART hit Dimorphos, it transferred its momentum into the asteroid.

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But that's not all. What really made a difference was the ejecta.

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The impact sent thousands of tons of rock and dust flying off into space,

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creating a kind of recoil effect that amplified the push on the asteroid.

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This was a huge breakthrough because it proved that if we ever find a real asteroid on a collision course with Earth,

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we might be able to nudge it away given enough time.

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DART was just the beginning.

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Future missions like ESA's HERA probe will return to Dimorphos in 2026 to study the aftermath and help us redefine asteroid deflection techniques.

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Another way to potentially move an asteroid is using a so-called gravity tractor.

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This sounds like science fiction, a Star Wars tractor beam, maybe.

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But it's actually based on the physics of gravity and how the mass of two objects affect one another.

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Instead of slamming an asteroid at high speed, a gravity tractor spacecraft would hover near the asteroid and slowly pull it off course.

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Here's how that works.

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We send a heavy spacecraft to a threatening asteroid, big enough that its gravitational pull can have an effect.

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The spacecraft parks near the asteroid, but instead of touching it, it hovers at a close distance.

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Even though the spacecraft is small compared to the asteroid, it still has mass,

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and its gravitational pull subtly tugs on the asteroid over time.

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Over years or even decades, this tiny but constant force slowly nudges the asteroid off its collision course with Earth.

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Of course, this method only works if we detect an asteroid threat decades in advance because the gravitational pull is very small and takes a long time to make a difference.

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It also requires a spacecraft with significant mass, which means launching a heavy probe into deep space, something that would take a lot of planning and resources.

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While Hollywood loves the idea of blowing up asteroids with nukes, Armageddon style, in reality, a gentle nudge decades in advance is a much safer and reliable way to protect our planet.

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If asteroids are the rocky leftovers of the solar system, comets are the icy wanderers.

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Comets are made of frozen gases, dust, and rock. They come from the Oort cloud and the Kuiper Belt, regions far beyond Neptune, where billions of these icy bodies orbit.

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When a comet gets close to the sun, the heat causes its icy surface to sublimate, turning directly from solid to gas.

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This creates the beautiful glowing coma and dust detail we see from Earth.

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Unlike asteroids, comets don't usually pose a threat to Earth, but every once in a while, a rogue one might swing too close for comfort.

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One of the most dramatic cometary events ever witnessed was the Shoemaker-Levy 9 impact on Jupiter in 1994.

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This comet had been torn apart by Jupiter's gravity and over six days its fragments slammed into the gas giant, creating massive explosions larger than Earth itself.

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The scars seen in Jupiter's atmosphere lasted for months.

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This was the first time humans had ever witnessed an impact between two solar system objects in real time, and it showed how Jupiter acts as sort of a cosmic vacuum cleaner,

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sucking in potential threats before they reach us.

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Before we wrap up, let's talk about Earth's second moon. Well, sort of.

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Recently, astronomers discovered 2024 PT-5, a small asteroid that's been caught in Earth's gravity, temporarily making it a mini-moon.

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Unlike our actual moon, it won't be here long. It'll likely drift away within a few months.

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Earth has had several of these temporary moons over the years. They're tiny, often no bigger than a car, and eventually slip away.

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Perhaps one day they could be targets for future space missions.

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I mentioned these mini-moons in more detail back in episode 38, in a discussion of orbital resonances in our solar system, so if you missed it, go back and give it a listen.

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If you found this episode helpful, let me know and feel free to send in your questions and observations.

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The easiest way to do that is by visiting our website, startrails.show.

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This is also a great way to share the show with friends. Until next time, keep looking up and exploring the night sky.

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Clear skies, everyone!