- 4613 - ASTEROID HITS EARTH ? - An asteroid hit the Earth just hours after being detected. It was the 3rd 'imminent impactor' of 2024. A small asteroid burned up in Earth's atmosphere off the coast of California just hours after being discovered and before impact monitoring systems had registered its trajectory.
------------------------------------------------ 4613 - ASTEROID HITS EARTH ?
- October 2024, an asteroid impacted Earth's
atmosphere just hours after being detected. Somehow, it managed to circumvent
impact monitoring systems during its approach to our planet. However, on the
bright side, the object measured just 3 feet in diameter and posed very little
threat to anything on Earth's surface.
-
- This asteroid, “2024 UQ”, was first discovered on October 22
by the Asteroid Terrestrial-impact Last Alert System (ATLAS) survey in
Hawaii. This is a network of four
telescopes that scan the sky for moving objects that might be space rocks on a
collision course with Earth. Two hours later, the asteroid burned up over the
Pacific Ocean near California, making it an "imminent impactor."
-
- The small amount of time between detection
and impact means impact monitoring systems, operated by the European Space
Agency's Near-Earth Object Coordination Center, didn't receive tracking data
about the incoming asteroid until after it struck Earth.
-
- ATLAS survey obtained images that included
detections of a small object in a high-probability collision course. However,
due to the location of the object near the edge of two adjacent fields, the
candidate was recognized as a moving object only a few hours later.
-
- By the time the astrometry reached the
impact monitoring systems, the impact had already happened. The asteroid was the third imminent impactor
detected this year. As for the two other asteroids that were been detected
within hours of impacting Earth in 2024, the first is known as “2024 BX1”. It
measured around 3.3 feet wide and burned up harmlessly over Berlin, Germany in
January. The other, “2024 RW1”, exploded over the Philippines on September 4.
-
- Planetary defense efforts that aim to
catalog the myriad of space rocks in our neck of the cosmic woods have become a
major priority for space agencies worldwide. Aside from the ATLAS survey,
Catalina Sky Survey, ESA's NEOCC and other projects like them, NASA is
developing a new infrared telescope known as NEO Surveyor to hunt for
potentially threatening near-Earth objects.
-
- But it's not all just about detection and
tracking. Space agencies are testing methods of redirecting incoming asteroids
should the need ever arise. In 2022, NASA's DART mission crashed an impactor
into a double asteroid system in an attempt to change its trajectory (the
endeavor was a success). China is also developing its own mission to deflect an
asteroid by 2030.
-
- The Taurid Meteoroid Stream, which is
possibly responsible for the famous Tunguska and Chelyabinsk impacts, probably
doesn't hide a civilization-killing asteroid.
A swarm of interplanetary dust, rocks, comets and asteroids thought to
be responsible for two famous impacts here on Earth has been found to be not
quite as menacing as astronomers had feared.
-
- The risk of being hit by a large asteroid
in the Taurid swarm is much lower than we believed, which is great news for
planetary defense.
-
- The swarm in question is the “Taurid
Meteoroid Complex”, which is a huge trail of debris that cuts across the path
of Earth's orbit around the sun. It's responsible for several meteor showers,
most notably the Southern Taurids that peak every year on November 5, and the
Northern Taurids on November 12.
-
- Meteor showers are produced when swarms of
tiny particles of dust, most just microns or millionths of a meter in size,
burn up in the Earth's atmosphere. However, lurking among all the dust are
larger chunks, from boulder-size rocks to full-blown asteroids. They all seem
to come from a parent body, the short-period “Comet 2P/Encke”.
-
- Comet 2P/Encke was the second periodic comet
to be discovered. And the first was Halley's Comet. A short-period comet is one that regularly
orbits the sun more often than once every 200 years. (Comets that take longer
than 200 years to complete an orbit are called long-period comets, and
originate from deep within the distant Oort Cloud.) In 2P/Encke's case, it
orbits every 3.3 years, the shortest orbit of any known periodic comet.
-
- “Encke” is pretty big for a short-period
comet, spanning about 3 miles in diameter. It's also joined on its orbit by
dozens of other minor bodies. The theory
is that 2P/Encke and all its companions originated from a much larger body that
fragmented as it came in from the outer solar system and got close to the heat
of the sun.
-
- Estimates of when this occurred vary, from
about 20,000 years ago to just 5,000 to 6,000 years ago, but the worry was that
there may be kilometer-sized objects lurking in the Taurid Complex that we
haven't discovered yet. Objects of this size could cause widespread damage were
they to collide with our planet.
-
- However, having surveyed a wide swathe of
sky around the Taurid Complex looking for any undiscovered objects there are
fewer kilometer-sized objects in the Taurid Complex than had been thought.
-
- Fortunately, we found that it's likely there
may only be a handful of asteroids, perhaps only nine to 14 of them, that fit
this large size class in the swarm The
parent object that originally created the swarm was probably closer to 10
kilometers in diameter rather than a
massive 62 miles object.
-
- Some uncertainty does remain over the
origin of the Taurid Complex, however. In 2014, astronomers using NASA's
Infrared Telescope Facility on Mauna Kea, Hawaii, studied the spectra of many
of the objects in the Taurid Complex and found a wide range of types, from
stony S-type asteroids to carbon-rich C-types.
-
- This diversity called into question the
idea that they'd all originated from a common parent body. However, a year later,
a subsequent study that analyzed the spectra of 33 fireballs hailing from the
Taurid Complex concluded that, despite the compositional variation, the
fireballs all had spectral and physical characteristics consistent with having
come from a comet that has broken apart.
-
- Regardless of their origin, and despite
being linked to the last two destructive impacts on Earth, the 1908 Tunguska
event and the 2013 Chelyabinsk airburst, it seems that the Taurid Complex does
not harbor any hidden dangers. The objects that are present within the stream
are on well-known orbits and do not currently pose a threat to Earth.
-
- We shouldn't get too comfortable. We still need to be vigilant about asteroid
impacts. But, we can probably sleep better knowing these results.
-
-
November 18, 2024 ASTEROID HITS
EARTH ? 4613
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--------------------- --- Tuesday, November 19,
2024
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