When a meteoroid enters the Earth’s atmosphere at a very high speed it heats up. This heating up produces a streak of light and is termed a meteor. When a meteor is bright enough, about the brightness of Venus or brighter, it becomes a fireball. Sometimes these fireballs explode in the atmosphere, becoming bolides. These bolides are bright enough to be seen even during the day.
Studying bolides as they pass through the atmosphere can help model larger asteroids, something of interest to the Planetary Defense Coordination Office (PDCO) which is run by NASA. These asteroids can be deadly if they are large enough, and learning how to predict their behavior is essential to protecting our planet from a devastating impact with long-term implications for the survival of many species on Earth.
Last week, a small asteroid was detected just two hours before it impacted Earth’s atmosphere. Luckily, it was only about 3 meters (10 feet) wide, and the space rock, now known as 2022 EB5 likely burned up in Earth’s atmosphere near Iceland at 21:22 UTC on March 11.
While it is wonderful that astronomers can detect asteroids of that size heading towards our planet — as well as determine the asteroid’s trajectory and precisely predicted its impact location — the last-minute nature of the discovery definitely causes a pause. What if it had been bigger?
New research shows that Mars has faced a constant rain of meteors during the last 600 million years. This finding contradicts previous research showing that the impact rate has varied, with prominent activity spikes. Why would anyone care how often meteors rained down on Mars, a planet that’s been dead for billions of years?
Because whatever Mars was subjected to, Earth was also likely subjected to.
In space, it’s almost always raining dust. Most of that dust is so small a microscope would have a hard time seeing it. Created by asteroid impacts, millions of these fine dust particles collide with Earth’s upper atmosphere every second. When they hit that atmosphere, they start a complex dance of plasmas and energy that can be difficult to see and understand.
An archeological dig has uncovered evidence of a massive cosmic airburst event approximately 3,600 years ago that destroyed an entire city near the Dead Sea in the Middle East. The event was larger than the famous Tunguska airburst event in Russia in 1908, with a blast 1,000 times more powerful than the Hiroshima atomic bomb. The event flattened the thriving city of Tall el-Hammam, located in what is now Jordan.
Planetary scientists estimate that each year, about 500 meteorites survive the fiery trip through Earth’s atmosphere and fall to our planet’s surface. Most are quite small, and less than 2% of them are ever recovered. While the majority of rocks from space may not be recoverable due to ending up in oceans or remote, inaccessible areas, other meteorite falls are just not witnessed or known about.
But new technology has upped the number known falls in recent years. Doppler radar has detected meteorite falls, as well as all-sky camera networks specifically on the lookout for meteors. Additionally, increased use of dashcams and security cameras have allowed for more serendipitous sightings and data on fireballs and potential meteorite falls.
A team of researchers is now taking advantage of additional technology advances by testing out drones and machine learning for automated searches for small meteorites. The drones are programmed to fly a grid search pattern in a projected ‘strewn field’ for a recent meteorite fall, taking systematic pictures of the ground over a large survey area. Artificial intelligence is then used to search through the pictures to identify potential meteorites.
The effects of ancient asteroid impacts on Earth are still evident from the variety of impact craters across our planet. And from the Chelyabinsk event back in 2013, where an asteroid exploded in the air above a Russian town, we know how devastating an “airburst” event can be.
Now, researchers in Antarctica have discovered evidence of a strange intermediate-type event – a combination of an impact and an airburst. The event was so devastating, its effects are still apparent even though it took place 430,000 years ago.
Telescopes have captured meteoroids hitting the Moon and several spacecraft imaged Comet Shoemaker–Levy 9 smacking into Jupiter in 1994. But impacts as they happen on another rocky world have never been observed.
However, the MESSENGER (MErcury Surface, Space ENvironment, GEochemistry and Ranging) mission may have seen an impact take place back in 2013. In looking at archival data from the mission, scientists found evidence of a meteoroid impact on Mercury. While this data isn’t a ‘no-doubt’ photo of the event, it does tell scientists more about impacts and how they affect Mercury’s wispy-thin atmosphere.
Here’s something we don’t see very often: an Earth-grazing meteoroid.
On September 22, 2020, a small space rock skipped through Earth’s atmosphere and bounced back into space. The meteoroid was spotted by the by a camera from the Global Meteor Network, seen in the skies above Northern Germany and the Netherlands. It came in as low as 91 km (56 miles) in altitude – far below any orbiting satellites – before it skipping back into space.
In a year of devastating wildfires, destructive derechos, early and active hurricanes, widespread social unrest, contentious politics and more — all amid an unprecedented global pandemic — it might seem fitting that ‘asteroid impact’ would be added to the 2020 bingo card.