- 3842 - STRANGE ASTEROIDS - in our inner circle? - July 17, 2022, NASA's Dawn spacecraft will rendezvous with the asteroid Vesta. This will be our best look yet at an asteroid, and what the probe digs up could help scientists answer several questions about this and the hundreds of thousands of asteroids that populate the solar system.
--------- 3842 - STRANGE ASTEROIDS - in our inner circle?
- Most asteroids, including “Vesta”, reside
in the doughnutlike ring of the main asteroid belt that peppers the space
between Mars and Jupiter. Other asteroids whirl in tight circles closer to the
sun than the Earth, while a large number of them share planets' orbits.
-
- However, some asteroids' orbits take them
on planet-crossing swings through the inner solar system. The first asteroid spotted was Ceres spotted
in 1801.
-
- “Ceres” is a water-logged sphere? The biggest asteroid by far explains why it
was discovered first and it makes up about a third of the asteroid belt's mass.
The object is so hefty that it's the only asteroid that has the gravitational
strength to pull itself into a sphere.
-
- On account of this roundness, Ceres is also
considered a "dwarf planet," a designation it shares with four other
objects in the solar system, including Pluto.
-
- After scoping out Vesta, the Dawn
spacecraft journies on to Ceres, arriving in 2015. The object is probably the
"wettest" asteroid, with large stores of water in its interior as
ice, though also possibly as a liquid layer beneath the surface.
-
- “Baptistina” is the mother of the dinosaur
killer. Baptistina is the name of one of
the youngest families of asteroids in the asteroid belt. Baptistina and its swarm were spawned some
160 million years ago by a smashup between a 37-mile-wide body and another
object about 106 miles in diameter. That
cataclysm created hundreds of large objects, some of which then drifted into a
collision course with Earth.
-
- One or several of these rocky shards of
shrapnel then plowed into our planet 65 million years ago and helped doom the
dinosaurs. The impact gouged out the Chicxulub crater, now buried by the
Yucatan peninsula and the Gulf of Mexico.
-
- The 100-million-year Baptistina barrage did
not spare the Moon. A meteorite scooped
out the giant Tycho crater about 109 million years ago.
-
- Many asteroids, believe it or not, have a
moon, and some even sport two satellites. “Kleopatra” asteroid has two moons, which were named Alexhelios
and Cleoselene. The metallic asteroid has an unusual dog-bone shape.
-
- The asteroid is roughly 135 by 58 by 50
miles in length, height and width. Its moons Alexhelios and Cleoselene are,
respectively, about 3 miles and 1.9 miles in diameter.
-
- Hektor is the biggest Trojan asteroid. Like Kleopatra, Hektor is very elongated,
with length and width dimensions of approximately 230 by 124 miles.
-
- “Hektor” has a moon as well. Unlike
Kleopatra, however, Hektor is not found in the main asteroid belt; instead, the
dark, reddish body dominates as the biggest of Trojan asteroids stuck in
Jupiter's orbit.
-
- These rocks lurk in what are known as the
L4 and L5 Lagrangian points two of the five zones in an orbit where the gravity
of two bodies (in this case, Jupiter and the Sun) balances out. L4 and L5 lie
ahead and behind, respectively of Jupiter.
-
- “Themis”, a large main belt asteroid,
stands out as the first and only asteroid known thus far to have ice on its
surface. In 2009, observations in infrared
light confirmed the presence of this ice, as well as carbon-containing, or
organic, molecules.
-
- These characteristics make Themis and
similar bodies called main belt comets good candidates for having delivered
water and carbon some of the ingredients of life to the surface of a young,
hot, dried-out Earth some four billion years ago.
-
- “Toutatis” is a tumbling dumbbell. Named after a Celtic god, Toutatis is one of
the oddest asteroids. Instead of rotating in an orderly fashion about an axis,
the double-lobed object chaotically tumbles. This unpredictable movement
partially derives from Toutatis being composed of two bodies barely in contact
with each other and from the influences of both Earth and Jupiter's gravity.
-
- Toutatis' path through the solar system has
it sweep close to Earth, but because the asteroid's orbit is chaotic, its exact
path and how close it might come to us centuries from now cannot be well
predicted.
-
- Like some other asteroids, Toutatis is said
to be a like a "rubble pile" fragments of rock that have
gravitationally come back together after a collision, but left many gaps
between them.
-
- Toutatis has made some close shaves to
Earth, and passed within 1,000,000 miles of Earth, or about four Moon distances,
back in 2004. Yet some rocks have made notably closer passes, and the one that
has most alarmed astronomers and the public alike is Apophis.
-
- Discovered in 2004 and named after the
Greek word for the evil Egyptian god of darkness, “Apophis” will return to the
neighborhood in 2029. At the time, scientists calculated that its impacting
Earth on that future pass were as high as 1 in 40, but subsequent measurements
have now relegated that possibility to almost nil .
-
- Panic peaked in December 2004, and Apophis
achieved a ranking of 4 on the Torino scale, the 10-point scale that rates the
risk of an object colliding with Earth (10 being an unquestioned apocalypse).
Although Apophis is now deemed a 0 for its 2029 pass, it will zoom a mere
18,600 miles above Earth's surface.
-
- A number of these other so-called Near
Earth Objects, or NEOs, have yet to be cataloged. Yet some that have pose no
threat, and benignly share Earth's orbit. At least four examples exist of
asteroids that follow Earth in horseshoe-shaped orbits; a new one, designated
2010 SO16.
-
- Most asteroids, including Vesta, reside in
the doughnutlike ring of the main asteroid belt that peppers the space between
Mars and Jupiter. Other asteroids whirl in tight circles closer to the sun than
the Earth, while a large number of them share planets' orbits. Some asteroids'
orbits take them on planet-crossing swings through the inner solar system.
January 10, 2022 STRANGE
ASTEROIDS - in our inner circle? 3821
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--------------------- --- Friday, January 27, 2023 ---------------------------
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