“I despise the Lottery. There’s less chance of you becoming a millionaire than there is of getting hit on the head by a passing asteroid.” – Brian May, astrophysicist, and guitarist.
Wait, hold on a moment! How can an asteroid actually hit us? I thought asteroids were those small, planet-like entities happily orbiting the sun. Are we talking about meteorites here? You know, those fiery rocks that plummet to Earth? But wait, Brian May specifically mentioned asteroids. I’m confused! Aren’t most asteroids located in the asteroid belt between Mars and Jupiter?”
Ah, I see now. Brian May was indeed referring to asteroids themselves. So, these asteroids, despite resembling miniature planets, have rather unstable orbits or paths around the sun. Imagine this: in the vastness of the asteroid belt, collisions between these wandering space rocks can occur. And when such a cosmic clash happens, it could potentially alter an asteroid’s trajectory, sending it hurtling towards our very own Earth. A captivating yet slightly unsettling thought, don’t you think?
Similarly, asteroids traveling from far might alter their paths by the gravitational impact of other planets or colliding with other space entities. So not just meteors (which when hit the Earth are called meteorites) hit the Earth but also asteroids.
Fact: Asteroids with a 1 km (0.62 mi) diameter strike Earth every 500,000 years on average. Large collisions – with 5 km (3 mi) objects – happen approximately once every twenty million years.
Asteroid hugs Earth – shock waves blooms.
Everyone commonly knows the story of the asteroid’s impact over 65 million years ago, and is believed to have eradicated the dinosaurs from Earth.
Have you ever heard of the Tunguska Event in Siberia?
The story of the witness who was thrown away from his chair and felt that his shirt was on fire is one of the famous stories of the event.
On June 30, 1908, the sky seemed to split in two, and there was a fire in the sky. Within no time, people heard a huge bang, stones fell as bullets fired, and Earth trembled with an earthquake. The shock waves pushed back the people, and the blowing hot air made people feel they were on fire.
Only in 1927 did scientists visit the place of impact to collect the details of the impact. Since they found no crater on Earth, they believed it must have exploded before reaching the Earth. The event was visible up to 800 km away. And it is said that the sky was so bright that people in even Asia could read the newspaper without electricity at midnight.
The trees had fallen radially, directing to the epicenter of the impact. But the trees close to the epicenter stood upright but with no branches resembling a light pole. Scientists believe the effect occurred so quickly that there was no time for it to transfer the push to the stem.
Chelyabinsk event
The Chelyabinsk event was the very recent event of the asteroid impact. On February 15, 2013, an asteroid exploded over the sky in Chelyabinsk, Russia. The blast had such strength that it even registered an impact over Antarctica. It shattered glasses and injured around 1200 people. Many cameras had recorded the videos of the blast.
Scientists later estimated that the asteroid had exploded around 19-24 km above the surface of the Earth. Hence even this impact had not left behind any crater on Earth. The scientists later found some pieces of the asteroid. The studies of those pieces showed that some were formed within the first 4 million years of the solar system’s history.
We will hit you – Surrender asteroid.
Dear Asteroids, don’t worry; we won’t hit you all. We are concerned only about a group of asteroids. The asteroids that orbit around Earth’s orbit are called near-earth asteroids. Don’t worry yet; we are not even worried about all the near-earth asteroids, but only about the potentially hazardous asteroids. The image below shows the paths of such asteroids around the Earth.
Blue – near earth asteroids(NEA); Orange – Potentially hazardous asteroids(PHA)
Image credits: (NASA/JPL-Caltech)
Studies have shown that not just the size of asteroids impacts the disaster that would happen but also the angle at which it would enter the Earth’s atmosphere.
For example: In the Chelyabinsk event, the asteroid was predicted to have entered at around 20 degrees angle. The impact would have been much more dangerous if the entry angle had been more significant, like about 60 degrees.
DART – the Double Asteroid Redirect Test:
DART is NASA’s most recent successful mission on September 26, 2022. In this mission, the spacecraft smashed into the asteroid moon Didymos B. Scientists concluded that the moon’s path was altered based on the data collected. In the future, we will use similar methods to change the direction of any asteroid that might be bound to enter the Earth’s environment and cause an impact.
Fact: The survey found there are likely 4,700 potentially hazardous asteroids, plus or minus 1,500 space rocks, that are larger than 330 feet (100 meters) wide and in orbits that occasionally bring them close enough to Earth to pose a concern, researchers said. They added that only about 30 percent of those objects have actually been found.
International Asteroid Day – June 30
In December 2016, the United Nations General Assembly declared June 30 “International Asteroid Day.” It meant everyone would observe the anniversary of the Tunguska impact over Siberia each year internationally and raise public awareness about the asteroid impact hazard.
Also, an asteroid day page is active, which shows all the updates about the asteroids and also events about asteroid day observed in various countries. It is to spread awareness of how the asteroid impacts would be and how the scientists prepare to face the impact through missions such as DART, as mentioned above.
It’s almost 115 years since the asteroid’s impact over Siberia on June 30. Observe the event by educating yourself about the asteroids and watching the fiction about the asteroids.
Reference:
- https://science.nasa.gov/science-news/science-at-nasa/2008/30jun_tunguska
- https://www.space.com/33623-chelyabinsk-meteor-wake-up-call-for-earth.html
- https://earthsky.org/space/what-is-the-tunguska-explosion/
- https://www.daysoftheyear.com/days/international-asteroid-day/
- https://www.space.com/15734-dangerous-asteroid-census-nasa-telescope.html